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Yu, Tsung-Hsing. "Numerical studies of heterojunction transport and High Electron Mobility Transistor (HEMT) devices." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/13035.
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Kim, Hyeong Nam. "Qualitative and Quantative Characterization of Trapping Effects in AlGaN/GaN High Electron Mobility Transistors." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250612796.
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Song, Di. "III-nitride normally-off low-density-drain high electron mobility transistors (LDD-HEMTs) /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECED%202007%20SONG.
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Lee, Kyoung-Keun. "Implementation of AlGaN/GaN based high electron mobility transistor on ferroelectric materials for multifunctional optoelectronic-acoustic-electronic applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28209.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: William. Alan Doolittle; Committee Member: Jeffrey Nause; Committee Member: Linda S. Milor; Committee Member: Shyh-Chiang Shen; Committee Member: Stephen E. Ralph.
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Bloom, Matthew Anthony. "DC, RF, and Thermal Characterization of High Electric Field Induced Degradation Mechanisms in GaN-on-Si High Electron Mobility Transistors." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/966.
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Gallium Nitride (GaN) high electron mobility transistors (HEMTs) are becoming increasingly popular in power amplifier systems as an alternative to bulkier vacuum tube technologies. GaN offers advantages over other III-V semiconductor heterostructures such as a large bandgap energy, a low dielectric constant, and a high critical breakdown field. The aforementioned qualities make GaN a prime candidate for high-power and radiation-hardened applications using a smaller form-factor. Several different types of semiconductor substrates have been considered for their thermal properties and cost-effectiveness, and Silicon (Si) has been of increasing interest due to a balance between both factors.
In this thesis, the DC, RF, and thermal characteristics of GaN HEMTs grown on Si-substrates will be investigated through a series of accelerated lifetime experiments. A figure of merit known as the critical voltage is explored and used as the primary means by which the GaN-on-Si devices are electrically strained. The critical voltage is defined as the specific voltage bias by which a sudden change in device performance is experienced due to a deformation of the target GaN HEMT’s epitaxial structure. Literature on the topic details the inevitable formation of pits and cracks localized under the drain-side of the gate contact that promote electrical degradation of the devices via the inverse piezoelectric effect. Characteristic changes in device performance due to high field strain are recorded and physical mechanisms behind observed degraded performance are investigated.
The study assesses the performance of roughly 60 GaN-on-Si HEMTs in four experimental settings. The first experiment investigates the critical voltage of the device in the off-state mode of operation and explores device recovery post-stress. The second experiment analyzes alterations in DC and RF performance under varying thermal loads and tracks the dependence of the critical voltage on temperature. The third experiment examines electron trapping within the HEMTs as well as detrapping methodologies. The final experiment links the changes in RF performance induced by high field strain to the small-signal parameters of the HEMT. Findings from the research conclude the existence of process-dependent defects that originate during the growth process and lead to inherent electron traps in unstressed devices. Electron detrapping due to high electric field stress applied to the HEMTs was observed, potentially localized within the AlGaN layer or GaN buffer of the HEMT. The electron detrapping in turn contributed to drain current recovery and increased unilateral performance of the transistor in the RF regime. Thermal experiments resulted in a positive shift in critical voltage, which enhanced gate leakage current at lower gate voltage drives.
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Masuda, Michael Curtis Meyer. "Investigation of Degradation Effects Due to Gate Stress in GaN-on-Si High Electron Mobility Transistors Through Analysis of Low Frequency Noise." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1169.
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Gallium Nitride (GaN) high electron mobility transistors (HEMT) have superior performance characteristics compared to Silicon (Si) and Gallium Arsenide (GaAs) based transistors. GaN is a wide bandgap semiconductor which allows it to operate at higher breakdown voltages and power. Unlike traditional semiconductor devices, the GaN HEMT channel region is undoped and relies on the piezoelectric effect created at the GaN and Aluminum Gallium Nitride (AlGaN) heterojunction to create a conduction channel in the form of a quantum well known as the two dimensional electron gas (2DEG). Because the GaN HEMTs are undoped, these devices have higher electron mobility crucial for high frequency operation. However, over time and use these devices degrade in a manner that is not well understood. This research utilizes low frequency noise (LFN) as a method for analyzing changes and degradation mechanisms in GaN-on-Si devices due to gate stress.
LFN is a useful tool for probing different regions of the device that cannot be measured through direct means. LFN generation in GaN HEMTs is based on the carrier fluctuation theory of 1/f noise generation which states fluctuations in the number of charge carriers results in conductance fluctuations that produce a Lorentzian noise spectrum. The summing Lorentzian noise spectra from multiple traps leads to 1/f and random telegraph signal (RTS) noise. The primary cause of carrier fluctuations are electron traps near the 2DEG and in the AlGaN bulk. These traps occur naturally due to dislocations and impurities in the manufacturing process, but new traps can be generated by the inverse-piezoelectric effect during gate stress.
This thesis introduces noise and presents a circuit to bias the devices and measure gate and drain LFN simultaneously. Three measurements are performed before and after gate DC stress at three different temperatures: DC characterization, capacitance-voltage (C-V) measurements, and LFN measurements. The DC characteristics show an increase in gate leakage after stress caused by an increase in traps after degradation consistent with trap assisted tunneling. However, the leakage current on the drain and source side differ before and after stress leading to the conclusion that the source side of the gate is more sensitive to gate stress. Gate leakage current on the drain side is also sensitive to temperature due to thermionic trap assisted tunneling. Hooge parameter calculations agree with previous research. The LFN results show an increase in gate and drain noise power, SIg(f) and SId(f), in accordance with increased gate leakage current under cutoff bias. RTS noise is also observed to increase in frequency with increased temperature. Activation energies for RTS noise are extracted and qualitatively linked to trap depth based on the McWhorter trap model.
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Perrin, Rémi. "Characterization and design of high-switching speed capability of GaN power devices in a 3-phase inverter." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI001/document.
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Le projet industriel français MEGaN vise le développement de module de puissance à base de compostant HEMT en GaN. Une des application industrielle concerne l’aéronautique avec une forte contrainte en isolation galvanique (>100 kV/s) et en température ambiante (200°C). Le travail de thèse a été concentré sur une brique module de puissance (bras d’onduleur 650 V 30 A). L’objectif est d’atteindre un prototype de facteur de forme peu épais, 30 cm2 et embarquant l’ensemble des fonctions driver, alimentation de driver, la capacité de bus et capteur de courant phase. Cet objectif implique un fort rendement énergétique, et le respect de l’isolation galvanique alors que la contrainte en surface est forte. Le manuscrit, outre l’état de l’art relatif au module de puissance et notamment celui à base de transistor GaN HEMT, aborde une solution d’isolation de signaux de commande à base de micro-transformateur. Des prototypes de micro-transformateur ont été caractérisés et vieillis pendant 3000 H pour évaluer la robustesse de la solution. Les travaux ont contribué à la caractérisation de plusieurs composants GaN afin de mûrir des modèles pour la simulation circuit de topologie de convertisseur. Au sein du travail collaboratif MEGaN, notre contribution ne concernait pas la conception du circuit intégré (driver de grille), tout en ayant participé à la validation des spécifications, mais une stratégie d’alimentation du driver de grille. Une première proposition d’alimentation isolée pour le driver de grille a privilégié l’utilisation de composants GaN basse-tension. La topologie Flyback résonante avec clamp permet de tirer le meilleur parti de ces composants GaN mais pose la contrainte du transformateur de puissance. Plusieurs technologies pour la réalisation du transformateur ont été validées expérimentalement et notamment une proposition originale enfouissement du composant magnétique au sein d’un substrat polymère haute-température. En particulier, un procédé de fabrication peu onéreux permet d’obtenir un dispositif fiable (1000 H de cyclage entre - 55 ; + 200°C), avec un rendement intrinsèque de 88 % pour 2 W transférés. La capacité parasite d’isolation est réduite par rapport aux prototypes précédent. Deux prototypes d’alimentations à forte intégration utilisent soit les transistors GaN basse tension (2.4 MHz, 2 W, 74 %, 6 cm2), soit un circuit intégré dédié en technologie CMOS SOI, conçu pour l’application (1.2 MHz, 2 W, 77 %, 8.5 cm2). Le manuscrit propose par la suite une solution intégrable de mesure de courant de phase du bras de pont, basé sur une magnétorésistance. La comparaison expérimentale vis à vis d’une solution à résistance de shunt. Enfin, deux prototypes de convertisseur sont décrits, dont une a pu faire l’objet d’une validation expérimentale démontrant des pertes en commutation réduitesThe french industrial project MEGaN targets the development of power module based on GaN HEMT transistors. One of the industrial applications is the aeronautics field with a high-constraint on the galvanic isolation (>100 kV/s) and ambient temperature (200°C). The intent of this work is the power module block (3 phases inverter 650 V 30 A). The goal is to obtain a small footprint module, 30 cm2, with necessary functions such as gate driver, gate driver power supply, bulk capacitor and current phase sensor. This goal implies high efficiency as well as respect of the constraint of galvanic isolation with an optimized volume. This dissertation, besides the state of the art of power modules and especially the GaN HEMT ones, addressed a control signal isolation solution based on coreless transformers. Different prototypes based on coreless transformers were characterized and verified over 3000 hours in order to evaluate their robustness. The different studies realized the characterization of the different market available GaN HEMTs in order to mature a circuit simulation model for various converter topologies. In the collaborative work of the project, our contribution did not focus on the gate driver chip design even if experimental evaluation work was made, but a gate driver power supply strategy. The first gate driver isolated power supply design proposition focused on the low-voltage GaN HEMT conversion. The active-clamp Flyback topology allows to have the best trade-off between the GaN transistors and the isolation constraint of the transformer. Different transformer topolgies were experimentally performed and a novel PCB embedded transformer process was proposed with high-temperature capability. A lamination process was proposed for its cost-efficiency and for the reliability of the prototype (1000 H cycling test between - 55; + 200°C), with 88 % intrinsic efficiency. However, the transformer isolation capacitance was drastically reduced compared to the previous prototypes. 2 high-integrated gate driver power supply prototypes were designed with: GaN transistors (2.4 MHz, 2 W, 74 %, 6 cm2), and with a CMOS SOI dedicated chip (1.2 MHz, 2 W, 77 %, 8.5 cm2). In the last chapter, this dissertation presents an easily integrated solution for a phase current sensor based on the magnetoresistance component. The comparison between shunt resistor and magnetoresistance is experimentally performed. Finally, two inverter prototypes are presented, with one multi-level gate driver dedicated for GaN HEMT showing small switching loss performance
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Brooks, Clive Raymond. "GaN microwave power FET nonlinear modelling techniques." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4306.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The main focus of this thesis is to document the formulation, extraction and validation of nonlinear models for the on-wafer gallium nitride (GaN) high-electron mobility (HEMT) devices manufactured at the Interuniversity Microelectronics Centre (IMEC) in Leuven, Belgium. GaN semiconductor technology is fast emerging and it is expected that these devices will play an important role in RF and microwave power amplifier applications. One of the main advantages of the new GaN semiconductor technology is that it combines a very wide band-gap with high electron mobility, which amounts to higher levels of gain at very high frequencies. HEMT devices based on GaN, is a fairly new technology and not many nonlinear models have been proposed in literature. This thesis details the design of hardware and software used in the development of the nonlinear models. An intermodulation distortion (IMD) measurement setup was developed to measure the second and higher-order derivative of the nonlinear drain current. The derivatives are extracted directly from measurements and are required to improve the nonlinear model IMD predictions. Nonlinear model extraction software was developed to automate the modelling process, which was fundamental in the nonlinear model investigation. The models are implemented in Agilent’s Advanced Design System (ADS) and it is shown that the models are capable of accurately predicting the measured S-parameters, large-signal singletone and two-tone behaviour of the GaN devices.
AFRIKAANSE OPSOMMING: Die hoofdoel van hierdie tesis is om die formulering, ontrekking en validasie van nie-lineêre modelle vir onverpakte gallium nitraat (GaN) hoë-elektronmobilisering transistors (HEMTs) te dokumenteer. Die transistors is vervaaardig by die Interuniversity Microelectronics Centre (IMEC) in Leuven, België. GaN-halfgeleier tegnologie is besig om vinnig veld te wen en daar word voorspel dat hierdie transistors ʼn belangrike rol gaan speel in RF en mikrogolf kragversterker toepassings. Een van die hoof voordele van die nuwe GaN-halfgeleier tegnologie is dat dit 'n baie wyd band-gaping het met hoë-elektronmobilisering, wat lei tot hoë aanwins by mikrogolf frekwensies. GaN HEMTs is 'n redelik nuwe tegnologie en nie baie nie-lineêre modelle is al voorgestel in literatuur nie. Hierdie tesis ondersoek die ontwerp van die hardeware en sagteware soos gebruik in die ontwikkeling van nie-lineêre modelle. 'n Intermodulasie distorsie-opstelling (IMD-opstelling) is ontwikkel vir die meting van die tweede en hoër orde afgeleides van die nie-lineêre stroom. Die afgeleides is direk uit die metings onttrek en moet die nie-lineêre IMD-voorspellings te verbeter. Nie-lineêre onttrekking sagteware is ontwikkel om die modellerings proses te outomatiseer. Die modelle word geïmplementeer in Agilent se Advanced Design System (ADS) en bewys dat die modelle in staat is om akkurate afgemete S-parameters, grootsein enkeltoon en tweetoon gedrag van die GaN-transistors te kan voorspel.
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Souguir-Aouani, Amira. "Conception d’une nouvelle génération de redresseur Schottky de puissance en Nitrure de Gallium (GaN), étude, simulation et réalisation d’un démonstrateur." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI093/document.
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Il y a actuellement un intérêt croissant pour la construction des dispositifs électroniques à semiconducteur pour les applications domotiques. La technologie des semiconducteurs de puissance a été essentiellement limitée au silicium. Récemment, de nouveaux matériaux ayant des propriétés supérieures sont étudiés en tant que remplaçants potentiels, en particulier : le nitrure de gallium et le carbure de silicium. L'état actuel de développement de la technologie 4H-SiC est beaucoup plus mature que pour le GaN. Cependant, l'utilisation de 4H-SiC n’est pas une solution économiquement rentable pour la réalisation des redresseurs Schottky 600 V. Les progrès récents dans le développement des couches épitaxiées de GaN de type n sur substrat Si offrent de nouvelles perspectives pour le développement des dispositifs de puissance à faible coût. C’est dans ce cadre que ma thèse s’inscrit pour réaliser avec ce type de substrat, un redresseur Schottky de puissance avec un calibre en tension de l’ordre de 600V. Deux architectures de redresseurs sont exposées. La première est une architecture pseudo-verticale proposée dans le cadre du projet G2ReC et la deuxième est une architecture latérale à base d’hétérojonction AlGaN/GaN obtenue à partir d'une structure de transistor HEMT. L’optimisation de ces deux dispositifs en GaN est issue de simulation par la méthode des éléments finis. Dans ce cadre, une adaptation des modèles de simulation à partir des paramètres physiques du GaN extraits depuis la littérature a été effectuée. Ensuite, une étude d’influence des paramètres géométriques et technologiques sur les propriétés statiques en direct et en inverse des redresseurs a été réalisée. Enfin, des structures de tests ont été fabriquées et caractérisées afin d’évaluer et d’optimiser le caractère prédictif des simulations par éléments finis. Ces études nous ont conduit à identifier l'origine des limites des structures de première génération et de définir de nouvelles structures plus performantesThere is increasing interest in the fabrication of power semiconductor devices in home automation applications. Power semiconductor technology has been essentially confined to Si. Recently, new materials with superior properties are being investigated as potential replacements, in particular silicon carbide (SiC) and gallium nitride (GaN). The current state of development of SiC technology is much more mature than for GaN. However, the use of 4H-SiC is not a cost effective solution for realizing a medium and high voltage Schottky diode. Recent advances on the development of thick n-type GaN epilayers on Si substrate offer new prospects for the development of a low-cost Schottky rectifiers for at least medium voltage range 600 V. In the context of our thesis, two types of GaN based rectifier architectures have been studied. The first one is a pseudo-vertical architecture proposed during previous G2ReC project. The second one has a lateral structure with AlGaN/GaN heterojunction, derived from a HEMT structure. The optimization of the Schottky rectifiers has been achieved by finite element simulations. As a first step, the models are implemented in the software and adjusted with the parameters described in the literature. The influence of the geometrical and physical parameters on the specific on-resistance and on the breakdown voltage has been analysed. Finally, the test devices have been realized and characterized to optimize and to validate the parameters of these models. These studies lead to identify the limits of the structures and create a new generation of powerful structures
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Gleason, Darryl A. "Scanned Probe Spectroscopy of Traps in Cross-Sectioned AlGaN/GaN Devices." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554299949405238.
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ISLAM, MD SHAHRUL. "Can Asymmetry Quench Self-Heating in MOS High Electron Mobility Transistors?" OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2736.
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High electron mobility transistors (HEMTs) have long been studied for high frequency and high-power application. Among widely known high electron mobility transistors, AlGaN/GaN HEMTs are having the upper hand due to high electron mobility of the GaN channel. Over the times, issues like current collapse, gate leakage, self-heating and gate lag have questioned the performance and reliability of these devices. In the recent years, engineers have come up with newer architectures to address some of these issues. Inserting a high-k dielectric oxide layer in the gate stack proved to be an effective solution to mitigate gate leakage, reduce interfacial traps and improve optimal working conditions. This work aims to study the reliability aspect of these so-called metal-oxide-semiconductor high electron mobility transistors (MOS-HEMT) specifically, HfO2 and HfZrO2 MOS-HEMTs. It was found through numerical simulations that though HfO2 and HfZrO2 dielectrics were able to mitigate gate leakage current, they tend to accumulate more heat in the channel region with respect to the conventional silicon nitride (SiN) passivated counterparts. Moreover, few asymmetric structures were proposed where silicon nitride was placed in the dielectric layer along with HfO2/HfZrO2. In this study it was found that these asymmetric structures showed superior thermal performance while showing near-zero gate leakage current.
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Chu, Rongming. "AlGaN-GaN single- and double-channel high electron mobility transistors /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202004%20CHU.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 74-82). Also available in electronic version. Access restricted to campus users.
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Malonis, Andrew C. "Quantitative defect spectroscopy on operating AlGaN/GaN high electron mobility transistors." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259597046.
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Ravindran, Vinod. "Design and fabrication of boron-containing III-nitrides based high electron mobility transistors." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47606.
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GaN-based HEMTs are among the most promising candidates for high-power and high-frequency applications; a niche for millimeter-wave technologies. Nitride materials indeed outperform other mainstream III-V materials (InP or GaAs) because of several properties, including wider bandgaps, high peak and saturation velocities, large breakdown voltages, together with good thermal conductivities. Nonetheless, the state-of-the-art of nitrides is not yet industrially mature to exploit the entire millimeter-wave range.
A way to push further performance is to develop innovative designs, notably by exploring novel materials. The purpose of this research was therefore to investigate the use of boron-containing III-nitrides in high electron mobility transistors (HEMTs).
The study was first conducted theoretically, through solving the Schrodinger-Poisson equation. Key parameters and relevant equations were derived to implement BGaN materials in our simulations. A GaN/ultrathin-BGaN/GaN heterojunction was showed to provide an electrostatic barrier to electrons and to improve the confinement of the two-dimensional electron gas. GaN back-barrier layers happen to limit leakage in the GaN buffer thanks to two effects: (i) a polarization-induced band discontinuity and (ii) a resistive barrier originating from excellent insulation properties of BGaN.
The study was then, experimentally, several growth campaigns were carried out that led to the fabrication of devices. First, we confirmed the key characteristics of BGaN materials by electrical and optical measurements. Second, we demonstrated the evidence of a significant enhancement of performance of standard AlGaN/GaN structures by the introduction of a BGaN layer in the buffer layer.
Compared to conventional AlGaN/GaN HEMTs, structures grown with BGaN back-barriers showed a significant improvement of static performances, transport properties, and trapping effects involving a limited current collapse in dynamic regime.
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Ben, ammar Hichem. "Investigation of ternary ΑlΙnΝ and quaternary ΑlGaΙnΝ alloys for high electron mobility transistors by transmission electron microscopy." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC241/document.
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Les semi-conducteurs III-V à base d’azote et leurs alliages possèdent des propriétés remarquables et sont largement étudiés depuis les années 90. En comparaison à d'autres semi-conducteurs III-V, Les alliages de type ; AlGaN, InGaN et AlInN, ont leurs bandes interdites, directes, du lointain ultra-violet au proche infrarouge. Ainsi, ils sont appropriés pour de nombreuses applications dans des domaines tant civils que militaires tout en montrant de meilleures performances. De plus, l'alliage quaternaire AlGaInN montre des propriétés intéressantes car il peut être épitaxié soit avec un paramètre de maille ou une polarisation ou une bande interdite accordé au GaN. De plus, avec AlInN, ces deux alliages pourraient, à terme, remplacer les barrières conventionnelles AlGaN/GaN pour les applications aux Transistors à Haute Mobilité Électroniques (HEMT) grâce à des performances supérieures prouvées théoriquement.Dans ce travail, nous avons étudié les alliages AlInN et AlGaInN dont la croissance a été faite par épitaxie en phase vapeur d’organométalliques (MOVPE). Pour cela, la microscopie électronique en transmission a été notre principal outil de caractérisation. Le but était de caractériser les défauts et les mécanismes de croissance pendant la MOVPE. Dans cette optique, l'incorporation de gallium dans la barrière en raison de la géométrie de la chambre de croissance menant à un alliage quaternaire a été étudiée. Le contrôle du taux de gallium est réalisé soit par un processus de nettoyage entre les épitaxies soit par les conditions de croissance. Les défauts ont été ensuite différenciés comme extrinsèques et intrinsèques. En effet, les dislocations et les domaines d'inversion dans le GaN produisent des défauts extrinsèques, tandis que, les « pinholes » non connectés aux dislocations et les « hillocks » responsables de la rugosité de surface sont définis comme intrinsèques. Les origines des défauts intrinsèques dépendent fortement des propriétés physiques des composés parents binaires. Ces dégradations systématiques sont observées même lorsque les conditions de croissance sont optimisées et quand la composition du film mince est changée ou son épaisseur augmentée.Notre travail propose des mécanismes différents pour expliquer les processus de dégradation pour les différents défauts observés et constitue donc un pas en avant pour la réalisation de HEMT à base de AlInN et AlGaInN de meilleure qualitéGroup III-Nitrides and their alloys exhibit outstanding properties and are being extensively investigated since the 90’s. In comparison to other III-V semiconductors, III-nitrides (AlGaN, InGaN, and AlInN) cover from deep ultraviolet (UV) to near infrared (IR) across the visible range of wavelengths. Thus, they are suitable for numerous applications both in civilian and military fields showing higher performances. Moreover, the quaternary alloy AlGaInN shows versatile properties as it can grow either lattice or polarization or bandgap matched to GaN. Alongside to AlInN, these two alloys are expected to replace conventional AlGaN/GaN High Electron Mobility Transistors (HEMT) barriers as higher performances have been theoretically demonstrated.In this work, we have studied AlInN and AlGaInN grown by metal organic vapor phase epitaxy (MOVPE) using mainly TEM. The aim was to characterize defects and the MOVPE growth alloying process. In this instance, the gallium incorporation in the barrier due to the geometry of the growth chamber leading to a quaternary alloy was studied. The control of the gallium content is achieved by a cleaning process between runs or by the growth condition. Defects were then differentiated as extrinsic and intrinsic. In this way, dislocations and inversion domains from the GaN buffer layer generate extrinsic defects, while, pinhole not connected to dislocations and individual hillocks responsible of surface roughening are termed as intrinsic. The origins of the latter defects depend strongly on the physical mismatches of the end-binary compound. These systematic degradations happen also with optimized growth conditions as soon as the nominal composition is changed and/or the thickness is increased.Our work proposes different mechanisms to explain defects generation processes which constitutes a forward step for higher quality HEMTs
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Arehart, Aaron R. "Investigation of electrically active defects in GaN, AlGaN, and AlGaN/GaN high electron mobility transistors." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253626881.
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Jia, Shuo. "AlGaN/GaN high electron mobility transistors on silicon substrate for RF/microwave applications /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202005%20JIA.
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Stevens, Lorin E. "Thermo-Piezo-Electro-Mechanical Simulation of AlGaN (Aluminum Gallium Nitride) / GaN (Gallium Nitride) High Electron Mobility Transistor." DigitalCommons@USU, 2013. http://digitalcommons.usu.edu/etd/1506.
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Due to the current public demand of faster, more powerful, and more reliable electronic devices, research is prolific these days in the area of high electron mobility transistor (HEMT) devices. This is because of their usefulness in RF (radio frequency) and microwave power amplifier applications including microwave vacuum tubes, cellular and personal communications services, and widespread broadband access. Although electrical transistor research has been ongoing since its inception in 1947, the transistor itself continues to evolve and improve much in part because of the many driven researchers and scientists throughout the world who are pushing the limits of what modern electronic devices can do. The purpose of the research outlined in this paper was to better understand the mechanical stresses and strains that are present in a hybrid AlGaN (Aluminum Gallium Nitride) / GaN (Gallium Nitride) HEMT, while under electrically-active conditions. One of the main issues currently being researched in these devices is their reliability, or their consistent ability to function properly, when subjected to high-power conditions. The researchers of this mechanical study have performed a static (i.e. frequency-independent) reliability analysis using powerful multiphysics computer modeling/simulation to get a better idea of what can cause failure in these devices. Because HEMT transistors are so small (micro/nano-sized), obtaining experimental measurements of stresses and strains during the active operation of these devices is extremely challenging. Physical mechanisms that cause stress/strain in these structures include thermo-structural phenomena due to mismatch in both coefficient of thermal expansion (CTE) and mechanical stiffness between different materials, as well as stress/strain caused by "piezoelectric" effects (i.e. mechanical deformation caused by an electric field, and conversely voltage induced by mechanical stress) in the AlGaN and GaN device portions (both piezoelectric materials). This piezoelectric effect can be triggered by voltage applied to the device's gate contact and the existence of an HEMT-unique "two-dimensional electron gas" (2DEG) at the GaN-AlGaN interface. COMSOL Multiphysics computer software has been utilized to create a finite element (i.e. piece-by-piece) simulation to visualize both temperature and stress/strain distributions that can occur in the device, by coupling together (i.e. solving simultaneously) the thermal, electrical, structural, and piezoelectric effects inherent in the device. The 2DEG has been modeled not with the typically-used self-consistent quantum physics analytical equations, rather as a combined localized heat source* (thermal) and surface charge density* (electrical) boundary condition. Critical values of stress/strain and their respective locations in the device have been identified. Failure locations have been estimated based on the critical values of stress and strain, and compared with reports in literature. The knowledge of the overall stress/strain distribution has assisted in determining the likely device failure mechanisms and possible mitigation approaches. The contribution and interaction of individual stress mechanisms including piezoelectric effects and thermal expansion caused by device self-heating (i.e. fast-moving electrons causing heat) have been quantified. * Values taken from results of experimental studies in literature
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Grémion, Emile. "Transistor balistique quantique et HEMT bas-bruit pour la cryoélectronique inférieure à 4. 2 K." Paris 11, 2008. http://www.theses.fr/2008PA112017.
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Pour augmenter la résolution globale des détecteurs à très basse température, aujourd'hui couramment utilisés dans de nombreux champs de la physique des particules et de l'univers, les expériences à venir ne pourront faire l'économie du développement d'une cryo-électronique performante, à la fois moins bruyante et plus proche du détecteur. Dans ce contexte, ce travail s'intéresse aux possibilités offertes par les gaz d'électrons bidimensionnels (2DEG) GaAlAs/GaAs à travers l'étude expérimentale de deux composants distincts : les QPC (Quantum Point Contact) et les HEMT (High Electron Mobility Transistor). En s'appuyant sur la quantification de la conductance dans les QPC, phénomène issu de la physique mésoscopique, un transistor balistique quantique fonctionnant à 4. 2 K a été réalisé. Le transport électronique à travers les bandes 1D permet d'obtenir un gain en tension supérieur à 1 avec une puissance dissipée d'environ 1 nW. En raison de leur très faible capacité d'entrée, ces dispositifs constituent également des candidats idéaux pour multiplexer des matrices de bolomètres haute impédance (collaboration DCMB). Les HEMT présentent des performances compatibles avec une utilisation à basse température, ayant une puissance dissipée de ~ 100 μW et un gain supérieur à 20. Le faible bruit en tension équivalent en entrée (1. 2 nV/Hz^(1/2) à 1 kHz et 0. 13 nV/Hz^(1/2) à 100 kHz) ouvre la voie à leur utilisation dans la lecture de détecteur de forte impédance. Conformément à la loi de Hooge, ces performances sont obtenues au détriment d'une capacité d'entrée élevée estimée à environ 60 pFNext generations of cryodetectors, widely used in physics of particles and physics of universe, will need in the future high-performance cryoelectronics less noisy and closer to the detector. Within this context, this work investigates properties of two dimensional electron gas GaAlAs/GaAs by studying two components, quantum point contact (QPC) and high electron mobility transistor (HEMT). Thanks to quantized conductance steps in QPC, we have realized a quantum ballistic transistor (voltage gain higher than 1), a new component useful for cryoelectronics thanks to its operating temperature and weak power consumption (about 1 nW). Moreover, the very low capacity of this component leads to promising performances for multiplexing low temperature bolometer dedicated to millimetric astronomy. The second study focused on HEMT with very high quality 2DEG. At 4. 2 K, a voltage gain higher than 20 can be obtained with a very low power dissipation of less than 100 μW. Under the above experimental conditions, an equivalent input voltage noise of 1. 2 nV/Hz^(1/2) at 1 kHz and 0. 12 nV/Hz^(1/2) at 100 kHz has been reached. According to the Hooge formula, these noise performances are get by increasing gate capacity estimated to 60 pF
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Malela-Massamba, Ephrem. "Développement et caractérisation de modules Technologiques sur semiconducteur GaN : application à la réalisation de cathodes froides et de transistor HEMT AlGaN/GAN." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1078.
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Les travaux présentés dans ce manuscrit sont axés sur le développement et la caractérisation de modules technologiques sur semiconducteurs à large bande interdite à base de nitrure de gallium (GaN), pour la réalisation de transistors et de cathodes froides. Ils ont été réalisés au sein du laboratoire III-V lab, commun aux entités : Alcatel - Thales - CEA Leti. Notre projet de recherche a bénéficié d'un soutien financier assuré par Thales Electron Devices (TED) et l'Agence Nationale de la Recherche ( ANR ). Concernant les transistors HEMT III-N, nos investigations se sont focalisées sur le développement des parties actives des transistors, incluant principalement la structuration des électrodes de grilles, l'étude de la passivation des grilles métalliques, ainsi que l'étude de diélectriques de grille pour la réalisation de structures MIS-HEMT.Les transistors MOS-HEMT « Normally-off » réalisés présentent des performances comparables à l'état de l'art, avec une densité de courant de drain maximum comprise entre 270 mA et 400 mA / mm, un ratio ION / IOFF > 1100, et des tensions de claquage > 200V. Les tensions de seuil sont comprises entre + 1,8 V et + 4 V. Nos contributions au développement des cathodes froides ont permis de démontrer une première émission dans le vide à partir de cathodes GaN, avec une densité de courant maximale de 300 µA / cm2 pour une tension de polarisation de 40 VThe results presented in this manuscript relate to technological developments and device processing on wide bandgap III-N semiconductor materials. They have been focused on III-N HEMT transistors and GaN cold cathodes. They have been realised within the III-V lab, which is a common entity between: Alcatel - Thales - CEA Leti. They have been financially supported by Thales Electron Devices company (TED) and the French National Research Agency ( ANR ). Regarding III-N HEMTs, our investigations have been focused on the development of device gate processing, which includes : the structuration of gate electrodes, the study of device passivation, and the realization of Metal-Insulator-Semiconductor High Mobility Electron Transistors ( MIS-HEMTs ). The “ Normally-off ” MOS-HEMT structures we have realized exhibit performances comparable to the state of the art, with a maximum drain current density between 270 and 400 mA / mm, a ION / IOFF ratio > 1.100, and a breakdown voltage > 200V. The threshold voltage values range between + 1,8 V and + 4V. We have also been able to demonstrate prototype GaN cold cathodes providing a maximum current density of 300 µA / cm2, emitted in vacuum for a bias voltage around 40 V
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Ucci, Russell. "Investigation of Interface Diffusion on the Reliability of AlGaN/GaN High Electron Mobility Transistor by Thermodynamic Modeling." Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1344529070.
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Walker, Dennis Eugene Jr. "The role of defects on Schottky and Ohmic contact characteristics for GaN and AlGaN/GaN high-electron mobility transistors." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1141766860.
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Chen, Lu. "Computerized evaluation of parameters for HEMT DC and microwave S parameter models." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179518920.
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Wächtler, Thomas. "Entwurf, Herstellung und Charakterisierung von GaN/AlGaN/GaN High Electron Mobility Transistoren für Leistungsanwendungen im GHz-Bereich." Universitätsbibliothek Chemnitz, 2005. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200501943.
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High Electron Mobility Transistoren (HEMTs),
basierend auf
dem Materialsystem GaN/AlGaN/GaN, wurden entworfen,
hergestellt und elektrisch charakterisiert.
Für das Maskendesign kam das CAD-Programm LasiCAD
zum Einsatz. Das Design umfasste bis zu sechs
Lithographieebenen.
Die Herstellung der Bauelemente geschah unter
Reinraumbedingungen und unter Nutzung einer
vorhandenen Technologie für Transistoren mit
kleiner Gate-Peripherie (Doppelgate-Transistoren),
die teilweise optimiert wurde. Daneben wurden
Prozesse zur Herstellung von Multifinger-HEMTs
entwickelt, wobei die Metallisierung der
Drainkontakte mittels Electroplating von Gold
vorgenommen wurde.
Zur elektrischen Charakterisierung der
Bauelemente wurden sowohl
Gleichstromcharakteristiken,
d.h. die Ausgangskennlinienfelder und
Verläufe der Steilheit, als auch das
Großsignalverhalten für cw-Betrieb bei 2 GHz
gemessen. Dabei zeigten die Transistoren
eine auf die Gatebreite bezogene
Ausgangsleistungsdichte
von mehr als 8 W/mm
und eine Effizienz größer als 40%,
einhergehend mit vernachlässigbarer
Drainstromdispersion der unpassivierten
Bauelemente.
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Gamarra, Piero. "Étude de composés semiconducteurs III-N à forte teneur en indium : application à l'optimisation des hétérostructures pour transistors à effet de champ piézo-électriques (HEMT)." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10009.
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Cette thèse est une contribution à l'étude de composés semiconducteurs InX Al1-X N à forte teneur en Indium. Ces composés présentent des propriétés très intéressantes pour des applications dans le domaine de l'amplification des hyperfréquences. L'objectif principal de la thèse est de définir des hétéro-structures de type AlGaInN / GaN, pour transistors à Effet de Champ Piézoélectrique (HEMT), épitaxiées sur substrats de saphir, silicium, et SiC, optimisées en vue de l'amplification hyperfréquence. Dans la première partie, nous étudions la croissance épitaxiale de couches minces du composé binaire GaN, en phase vapeur, à partir de précurseurs organométalliques (MOVPE), dans des conditions optimisées pour obtenir des couches fortement résistives. La deuxième partie est consacrée à l'étude de structures HEMT AlGaN/GaN sur SiC et sur silicium. Sur SiC, nous montrons la forte influence des propriétés du substrat sur les propriétés électriques des structures HEMT. Nous avons étudié une structure nouvelle incluant une fine couche de AlN entre les couches AlGaN et GaN et évalué les performances de transistors HEMT AlGaN/GaN et AlGaN/AlN/GaN sur SiC et sur Silicium (111). La partie suivante est consacrée à la croissance de composés ternaires InAlN. Nous avons étudié l'influence de la température de croissance et du rapport V/III sur les propriétés structurales de InAlN. Les conditions optimales ont été utilisées pour la réalisation de structures HEMT InAlN/AlN/GaN. Nous démontrons l'influence considérable de la couche AlN sur les propriétés électriques de ces structures. Enfin, nous discutons les performances obtenues sur des transistors à effet de champ InAlN/AlN/GaN sur SiCThis work reports on the metal-organic vapor phase epitaxy and on the characterisation of III-N GaInAlN heterostructures for High Electron Mobility Transistors. In a first part, the heteroepitaxy of semiinsulating GaN layers on sapphire, SiC and silicon is presented as the basis for the subsequent growth of III-N HEMT structures. The influence of suitable nucleation layers on the properties of GaN is presented and discussed. A second part deals with AlGaN/GaN HEMT structures grown on SiC and on Si (111) wafers. The influence of SiC substrate properties on the electrical performances of AlGaN/GaN HEMT is presented. A novel structure, including a thin AlN interlayer between the GaN buffer layer and the AlGaN barrier layer has also been introduced. The section is completed by device results obtained on selected heterostructures. A study of the impact of selected growth parameter (i.e. growth temperature, V/III ratio) on the structural and surface properties of InAlN layers is then presented. The optimized conditions have been used for the growth InAlN/AlN/GaN HEMT structures which have been thoroughly characterized. The electrical properties of the structures were found to be strongly dependent on the growth conditions of the AlN interlayer (e.g. deposition time, V/III ratio). Finally, state of the art device results obtained with InAlN/AlN/GaN heterostructures are presented
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Jones, Jason Patrick. "Electro-thermo-mechanical characterization of stress development in AlGaN/GaN HEMTs under RF operating conditions." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53528.
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Gallium nitride (GaN) based high electron mobility transistors (HEMTs) offer numerous benefits for both direct current (DC) and radio frequency (RF) power technology due to their combination of large band gap, high electrical breakdown field, high peak and saturation carrier velocity, and good stability at high temperatures. In particular, AlGaN/GaN heterostructures are of great interest because of the unique conduction channel that develops as a result of the spontaneous and piezoelectric polarization that occurs in these layers. This channel is a vertically confined plane of free carriers that is often called a 2 dimensional electron gas (or 2DEG). Although these devices have shown an improvement in performance over previous heterostructures, reliability issues are a concern because of the high temperatures and electric fields that develop during operation. Therefore, characterizing electrical and thermal profiles within AlGaN/GaN HEMTs is critical for understanding the various factors that contribute to device failures. Little research has been performed to model and characterize these devices under RF bias conditions, and is therefore of great interest. Under pulsed conditions, a single cycle consists of an “on-state” period where power is supplied to the device and self-heating occurs, followed by an “off-state” period where no power is supplied to the device and the device cools. The percentage of a single cycle in which the device is powered is called the duty cycle.
In this work, we present a coupled electro-thermo-mechanical finite-element model for describing the development of temperature, stress, and strain profiles within AlGaN/GaN HEMTs under DC and AC power conditions for various duty cycles. It is found that bias conditions including source-to-drain voltage, source-to-gate voltage, and pulsing frequency directly contribute to the electro-thermo-mechanical response of the device, which is known to effect device performance and reliability. The model is validated by comparing numerical simulations to experimental electrical curves (Ids-Vds) and experimental strain measurements performed using scanning joule expansion microscopy (SJEM). In addition, we show how the operating conditions (bias applied and AC duty cycle) impact the thermal profiles of the device and outline how the stress in the device changes through a pulsed cycle due to the changing thermal and electrical profiles. Qualitatively, the numerical model has good agreement across a broad range of bias conditions, further validating the model as a tool to better understand device performance and reliability.
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Waechtler, Thomas, Michael J. Manfra, Nils G. Weimann, and Oleg Mitrofanov. "High Power GaN/AlGaN/GaN HEMTs Grown by Plasma-Assisted MBE Operating at 2 to 25 GHz." Universitätsbibliothek Chemnitz, 2005. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200500380.
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Heterostructures of the materials system GaN/AlGaN/GaN were grown by molecular beam epitaxy on 6H-SiC substrates and high electron mobility transistors (HEMTs) were fabricated. For devices with large gate periphery an air bridge technology was developed for the drain contacts of the finger structure. The devices showed DC drain currents of more than 1 A/mm and values of the transconductance between 120 and 140 mS/mm. A power added efficiency of 41 % was measured on devices with a gate length of 1 µm at 2 GHz and 45 V drain bias. Power values of 8 W/mm were obtained. Devices with submicron gates exhibited power values of 6.1 W/mm (7 GHz) and 3.16 W/mm (25 GHz) respectively. The rf dispersion of the drain current is very low, although the devices were not passivatedHeterostrukturen im Materialsystem GaN/AlGaN/GaN wurden mittels Molekularstrahlepitaxie auf 6H-SiC-Substraten gewachsen und High-Electron-Mobility-Transistoren (HEMTs) daraus hergestellt. Für Bauelemente mit großer Gateperipherie wurde eine Air-Bridge-Technik entwickelt, um die Drainkontakte der Fingerstruktur zu verbinden. Die Bauelemente zeigten Drainströme von mehr als 1 A/mm und Steilheiten zwischen 120 und 140 mS/mm. An Transistoren mit Gatelängen von 1 µm konnten Leistungswirkungsgrade (Power Added Efficiency) von 41 % (bei 2 GHz und 45 V Drain-Source-Spannung) sowie eine Leistung von 8 W/mm erzielt werden. Bauelemente mit Gatelängen im Submikrometerbereich zeigten Leistungswerte von 6,1 W/mm (7 GHz) bzw. 3,16 W/mm (25 GHz). Die Drainstromdispersion ist sehr gering, obwohl die Bauelemente nicht passiviert wurden
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Callet, Guillaume. "Caractérisation et modélisation de transistors HEMT AlGaN/GaN et InAlN/GaN pour l’amplification de puissance en radio-fréquences." Limoges, 2011. https://aurore.unilim.fr/theses/nxfile/default/3c0fde17-3720-49cd-9824-bd071826245e/blobholder:0/2011LIMO4033.pdf.
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Ce document traite de la caractérisation de composants HEMT à base de GaN en vue de leur modélisation. Une caractérisation exhaustive des transistors à base d’InalN/GaN et AlGaN/GaN est réalisée. Une importance particulière est donnée aux méthodes de caractérisation thermique, avec l’utilisation de la méthode 3ω pour la mesure de l’impédance thermique. Une étude des facteur d’échelle du modèle linéaire est également abordée. Le modèle non-linéaire présenté est développé afin d’élargir son champ d’application à l’amplification de puissance et à la commutation. Enfin, il est utilisé pour la réalisation du premier amplificateur de puissance utilisant la technologie InAlN en bande KaThis report deals with the characterization of GaN HEMTs devices in order to create their model. An exhaustive characterization has been realized for AlInN/GaN and AlGaN/GAN based HEMTs. A special care has been given to the different thermal characterization methods, with the use of the 3ω method for the measurement of the thermal impedance. A study of scaling rules for small-signal model is presented. The non-linear model presented is developed in order to extend his application domain to the power amplification and power switches. Finally it is used in the design of the first poser amplifier base on AlInN technology in Ka-band
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Lin, Chung-Han. "The Effects of Thermal, Strain, and Neutron Irradiation on Defect Formation in AlGaN/GaN High Electron Mobility Transistors and GaN Schottky Diodes." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1371466261.
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Kim, Tong-Ho. "Solid source molecular beam epitaxy of InP-based composite-channel high electron mobility transistor structures of microwave and millimeter-wave power applications." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/14859.
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Meliani, Chafik. "Circuits intégrés amplificateurs à base de transistors HEMT pour les transmissions numériques à très haut débit (≥40 Gbit/s)." Paris 7, 2003. http://www.theses.fr/2003PA077172.
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Mohamad, Isa Muammar Bin. "Low Noise Amplifiers using highly strained InGaAs/InAlAs/InP pHEMT for implementation in the Square Kilometre Array (SKA)." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/low-noise-amplifiers-using-highly-strained-ingaasinalasinp-phemt-for-implementation-in-the-square-kilometre-array-ska(31b6cbae-7b7e-43fe-a612-b3555dd2263d).html.
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The Square Kilometre Array (SKA) is a multibillion and a multinational science project to build the world’s largest and most sensitive radio telescope. For a very large field of view, the combined collecting area would be one square kilometre (or 1, 000, 000 square metre) and spread over more than 3,000 km wide which will require a massive count of antennas (thousands). Each of the antennas contains hundreds of low noise amplifier (LNA) circuits. The antenna arrays are divided into low, medium and high operational frequencies and located at different positions to boost up the telescope’s scanning sensitivity.The objective of this work was to develop and fabricate fully on-chip LNA circuits to meet the stringent requirements for the mid-frequency array from 0.4 GHz to 1.4 GHz of the SKA radio astronomy telescope using Monolithic Microwave Integrated Circuit technology (MMIC). Due to the number of LNA reaching figures of millions, the fabricated circuits were designed with the consideration for low cost fabrication and high reliability in the receiver chain. Therefore, a relaxed optical lithography with Lg = 1 µm was adopted for a high yield fabrication process.Towards the fulfilment of the device’s low noise characteristics, a large number of device designs, fabrication and characterisation of InGaAs/InAlAs/InP pHEMTs were undertaken. These include optimisations at each critical fabrication steps. The device’s high breakdown and very low gate leakage characteristics were further improved by a combination of judicious epitaxial growth and manipulation of materials’ energy gaps. An attempt to increase the device breakdown voltage was also employed by incorporating Field Plate structure at the gate terminal. This yielded the devices with improvements in the breakdown voltage up to 15 V and very low gate leakage of 1 µA/mm, in addition to high transconductance (gm) characteristic. Fully integrated double stage LNA had measured NF varying from 1.2 dB to 1.6 dB from 0.4 GHz to 1.4 GHz, compared with a slightly lower NF obtained from simulation (0.8 dB to 1.1 dB) across the same frequency band.These are amongst the attractive device properties for the implementation of a fully on-chip MMIC LNA circuits demonstrated in this work. The lower circuit’s low noise characteristic has been demonstrated using large gate width geometry pHEMTs, where the system’s noise resistance (Rn) has successfully reduced to a few ohms. The work reported here should facilitate the successful implementation of rugged low noise amplifiers as required by SKA receivers.
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Bertrand, Dimitri. "Etude des mécanismes de formation des contacts ohmiques pour des transistors de puissance sur Nitrure de Gallium." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI060/document.
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Cette thèse s’inscrit dans le cadre du développement d’une filière de transistors de puissance à base de nitrure de Gallium au CEA-LETI. Ces transistors, en particulier les HEMT utilisant l’hétérostructure AlGaN/GaN, présentent des propriétés très utiles pour les applications de puissance. L’essor de cette technologie passe notamment par le développement de contacts ohmiques peu résistifs. Cette thèse a pour objectif d’approfondir la compréhension des mécanismes de formation du contact ohmique sur une structure AlGaN/GaN. Dans un premier temps, une étude thermodynamique sur une dizaine de métaux de transition utilisables comme base de l’empilement métallique du contact a été menée, ce qui a permis de retenir une métallisation Ti/Al. Puis, les différentes réactions physico-chimiques de cet empilement avec des substrats nitrurés ont été étudiées en faisant varier la composition et les températures de recuit de formation du contact ohmique. Enfin, plusieurs études sur structure AlGaN/GaN couplant caractérisations électriques et physico-chimiques ont permis d’identifier des paramètres décisifs pour la réalisation d’un contact ohmique, peu résistif et nécessitant une faible température de recuitThis PhD is part of the development of Gallium nitride based power transistors at the CEA-LETI. These transistors, especially those based on AlGaN/GaN heterostructure, are very promising for power electronics applications. The goal of this PhD is to increase the knowledge of the mechanisms responsible for the ohmic contact formation on a AlGaN/GaN structure. First, a thermodynamic study of several transition metals has been performed, leading us to select Ti/Al metallization. Then, the multiple physico-chemical reactions of this stack with nitride substrates have been studied depending on the stack composition and the annealing temperature. Finally, several studies on AlGaN/GaN structure coupling both physico-chemical and electrical characterizations reveal different decisive parameters for the formation of an ohmic contact with a low-resistance and a low annealing temperature
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MELIANI, Chafik. "Circuits intégrés amplificateurs à base de transistors HEMT pour les transmissions numériques à très haut débit (>=40 Gbit/s)." Phd thesis, Université Paris-Diderot - Paris VII, 2003. http://tel.archives-ouvertes.fr/tel-00007587.
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La systématisation de la conversion analogique/numérique a eu pour effet d'uniformiser le mode de transmission de données aux transmissions numériques ; et notamment sur fibre optique. Dans ce cadre, cette thèse traite des méthodologies de conception et faisabilité de circuits amplificateurs de signaux rapides. Après l'étude de l'effet des éléments parasites sur les structures amplificatrices de base (spécifiquement, les problèmes de chemins de masse, et de référencement de signaux d'entrée), la théorie de distribution est appliquée à la technologie coplanaire InP ; où via une méthodologie que nous avons cherché à systématiser (notamment pour les conditions d'égalité et de faible variation des délais de groupe), sont réalisés des amplificateurs large bande avec Fc=92GHz et entre autres, un produit gain-bande à l'état de l'art de 410 GHz. Au delà des problèmes posés par la technologie coplanaire tels que les discontinuités de masse et la nécessité de préserver le mode de propagation coplanaire, elle ouvre de nouvelles possibilités telles que des lignes artificielles d'entrée/sortie à longueurs identiques, et permet une compacité plus élevée que celle des techniques micro-ruban. Les limites de l'amplification différentielle sont ensuite investies et repoussées, en proposant une structure innovante : la paire différentielle distribuée ; alliant ainsi le fonctionnement à courant constant du mode différentiel (donc avec un degré de liberté supplémentaire, pour le potentiel DC en sortie), à l'aspect large bande du distribué. Des amplificateurs avec 4 Vpp en sortie à 40 Gbit/s ont ainsi été réalisés en pHEMT GaAs. Ce résultat, permettrait à terme, l'élimination des capacités de passage dans les modules driver et la conception de drivers de modulateur mono-puce.
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El, Rafei Abdelkader. "Analyse des effets dispersifs dans les transistors radiofréquences par mesures électriques." Limoges, 2011. https://aurore.unilim.fr/theses/nxfile/default/381740cc-fba9-4386-9b9d-0e0dd1113527/blobholder:0/2011LIMO4037.pdf.
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Les amplificateurs de puissance (PA) sont des éléments clés des terminaux de télécommunications et de radar aux radios fréquences. Le potentiel des PA est limité par des phénomènes de dispersion. Dans ce contexte, nous intéressons à la caractérisation des phénomènes thermiques dans les transistors TBH de différentes technologies (AsGa, SiGe et InP) et la caractérisation des effets thermiques et pièges dans les transistors HEMT à base GaN (AlGaN et AlInN) en basses fréquences. Un banc de mesure des paramètres S basse fréquences [10 Hz, 40 GHz] siège des phénomènes parasites non linéaires qu’il faut prendre en compte pour pouvoir réaliser des simulations fiables, est mis en place. Une méthode précise et simple pour la mesure de l’impédance thermique de TBH réalisés avec différentes technologies a été proposée. Cette méthode s’appuie sur des mesures électriques basses fréquences. Une étude approfondie de la caractérisation des phénomènes de dispersion basse fréquences (BF) dans les transistors HEMT à base GaN a été menée. Les effets de pièges sont étudiés pour les deux technologies (AlGaN/GaN et AlInN/GaN) avec la méthode de la spectroscopie d’admittance afin de quantifier les pièges de niveaux profondsPower amplifiers (PAs) are key elements of telecommunications and radar front ends at radio frequencies. The potential of the PA is limited by the phenomena of dispersion. In this context, we are interested in the characterization of thermal phenomena in the HBT transistors of different technology (GaAs, InP and SiGe) and characterization of thermal and traps effects in HEMT transistors based on GaN (AlGaN and AlInN) at low frequencies. A bench for low frequency S-parameters measurement [10 Hz, 40 GHz] is set up to enable us to study the behavior of the new components in the frequency range seat of nonlinear parasitic phenomena. A simple, yet accurate, method to experimentally characterize the thermal impedance of Hetero junction Bipolar Transistors (HBT) with different technologies proposed. This method relies on low frequency S-parameters measurements. A detailed study has been initiated to characterize the phenomena of low frequency dispersion in the HEMT transistors based on GaN. The thermal and traps effects are studied for both technologies (AlGaN/GaN and AlInN/GaN) with the method of admittance spectroscopy to quantify the levels of deep traps
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Umana-Membreno, Gilberto A. "A study of gamma-radiation-induced effects in gallium nitride based devices." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0015.
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[Truncated abstract] Over the past decade, the group III-nitride semiconducting compounds (GaN, AlN, InN, and their alloys) have attracted tremendous research efforts due to their unique electronic and optical properties. Their low thermal carrier generation rates and large breakdown fields make them attractive for the development of robust electronic devices capable of reliable operation in extreme conditions, i.e. at high power/voltage levels, high temperatures and in radiation environments. For device applications in radiation environments, such as space electronics, GaN-based devices are expected to manifest superior radiation hardness and reliability without the need for cumber- some and expensive cooling systems and/or radiation shielding. The principle aim of this Thesis is to ascertain the level of susceptibility of current GaN-based elec- tron devices to radiation-induced degradation, by undertaking a detailed study of 60Co gamma-irradiation-induced defects and defect-related effects on the electrical characteristics of n-type GaN-based materials and devices . . . While the irradiation-induced effects on device threshold voltage could be regarded as relatively benign (taking into account that the irradiation levels employed in this study are equivalent to more than 60 years exposure at the average ionising dose rate levels present in space missions), the observed device instabilities and the degradation of gate current characteristics are deleterious effects which will have a significant impact on the performance of AlGaN/GaN HEMTs operating in radiation environments at low temperatures, a combination of conditions which are found in spaceborne electronic systems.
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Bousbia, Hind. "Analyse et développement de la caractérisation en puissance, rendement et linéarité de transistors de puissance en mode impulsionnel." Limoges, 2006. http://aurore.unilim.fr/theses/nxfile/default/f409eab6-d21e-443d-9d6b-b14970380c32/blobholder:0/2006LIMO0063.pdf.
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Il est aujourd’hui admis que les semi-conducteurs à large bande interdite vont permettre de repousser les frontières atteintes à ce jour dans le domaine de la génération de puissance hyperfréquence. L’analyse des principaux critères technologiques (physiques et électriques) des matériaux grands gap, et plus précisément du GaN montre que ce dernier est un candidat sérieux pour les applications de télécommunications et radar. Un modèle électrothermique de ces transistors hyperfréquences à FET sur GaN a été utilisé dans ces travaux pour analyser les comportements transitoires lents dus aux effets thermiques et aux effets de pièges. Une comparaison des performances en puissance, rendement et linéarité a été faite entre les résultats de simulation et ceux de mesure pour des signaux de deux types : CW impulsionnels et Bi porteuses impulsionnels. L’utilisation de signaux CW impulsionnels a permis une validation pratique des modèles électrothermiques de transistors HBT et une expertise de différentes filières technologiques de ces transistors. L’utilisation de signaux bi porteuses impulsionnels a permis d’observer des tendances sur les compromis rendement/linéarité en fonction des effets de pièges de transistors FET GaN. Des mesures réalisées sur une configuration originale d’un banc de caractérisation de type « load-pull » pour une mesure d’intermodulation en mode pulsé ont permis de montrer les limitations actuelles des modèles de ces transistors dans le cadre de simulations de fonctionnement dynamiqueIt is admitted today that wide band-gap materials will make it possible to push back the borders reached to date in the field of RF power generation. The analysis of the properties of wide band-gap materials, and especially the GaN material, highlights that it is a serious candidate for telecommunication and radar applications. RF field effect transistors on GaN are prone to show dispersive behaviors due to heating and trapping effects. A non linear electrothermal model of these high frequency FETs transistors on GaN used in this work makes possible the analysis of dispersive behaviors due to heating and trapping effects. A comparison of performances in terms of output power, power added efficiency and linearity has been made between simulation and measurement results for two type of excitation: one tone pulsed signal and two tones pulsed signal. The use of a one tone pulsed excitation permitted the validation of an HBT electrothermal model and the expertise of different technological process of these transistors. The use of a two tone pulsed excitation has permitted to observe the trade-offs between power added efficiency and linearity versus trapping effects. The measurements carried out on an original configuration of the load pull set up for intermodulation measurements under pulsed conditions had shown the actual limitations of the transistor model
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Venkatachalam, Anusha. "Investigation of self-heating and macroscopic built-in polarization effects on the performance of III-V nitride devices." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29669.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.Committee Chair: Yoder, Douglas; Committee Member: Graham, Samuel; Committee Member: Allen, Janet; Committee Member: Klein, Benjamin; Committee Member: Voss, Paul. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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El, Bondry Nadia. "Epitaxie d’hétérostructures innovantes pour la montée en fréquence des HEMTs à base de GaN." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4080.
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Les travaux de cette thèse portent sur le développement et l’étude de transistors à haute mobilité électronique à base de GaN comportant une approche innovante pour leur montée en fréquence de fonctionnement. Cette technologie repose sur l’épitaxie localisée de caissons de GaN fortement dopé de type n au niveau des contacts ohmiques. Ces caissons ont la particularité d’être en contact direct avec le gaz d’électrons du canal, ce qui doit permettre de réduire les résistances de contact. La conduction des électrons dans le contact et à l’interface avec le gaz d’électrons est facilitée si le dopage de type n est suffisamment élevé. La zone d’interface entre le gaz d’électrons et le n-GaN est une zone sensible, ce qui demande une préparation adaptée avant l’épitaxie localisée. Les résistances d’interface ont été extraites des mesures des différents motifs de test TLM afin de qualifier la qualité de l’interface. La réduction des distances entre contacts de source, de grille et de drain, permet d’augmenter la fréquence de fonctionnement des transistors. L’approche développée ici permet également de garantir un meilleur contrôle des distances en s’affranchissant du recuit des contacts ohmiques à haute température responsable du fluage des métaux. Cette thèse comprend trois volets principaux : l’étude de la croissance localisée de caissons de GaN fortement dopé n par deux techniques d’épitaxie largement utilisées dans le domaine (MBE et MOVPE), le développement du procédé technologique de fabrication ainsi que la caractérisation électrique des transistors avec des caissons de n-GaN au niveau des contacts ohmiques. L’étude a été réalisée sur différentes structures HEMT avec des barrières en alliages ternaires (AlGaN) et quaternaires (InAlGaN)This thesis focuses on the design, the fabrication and the characterization of GaN-based high electron mobility transistors (HEMTs) including the localised regrowth of highly doped n-type GaN to side contact the bi-dimensional electron gas (2DEG). These regrowth regions have the particularity of being in direct contact with the 2DEG, resulting in lower ohmic contact resistances. The approach developed here also ensures better lateral definition of the contacts by avoiding or reducing the high-temperature anneal of ohmic contacts, which is responsible for metal diffusion. This allows the reduction of the distance between source and drain contacts, resulting in an increase of the operating frequency and of the efficiency of the transistors. This thesis covers three main topics: the study of the localized growth of heavily n-doped GaN regions by two epitaxy techniques widely used in the field (MBE and MOVPE), the development of the technological manufacturing process and the electrical characterization of transistors with n-GaN regrowth at the ohmic contacts. The study was carried out on different HEMT structures with ternary (AlGaN) and quaternary (InAlGaN) alloy barriers. We took into account and studied several parameters, including the topology of the devices, the metallization schemes, the doping level and the conductivity of the n-GaN layers. In addition, we studied suitable surface preparations before the regrowth as well as the impact of the n-GaN growth conditions on the critical interface zone between the 2DEG and the n-GaN. We extracted the contact resistances on a large number of samples from the measurements of Transmission Line Method (TLM) patterns in order to quantify the different contributions, including the quality of the interface. We then used the best sets of parameters to fabricate GaN-based RF devices and we investigated their DC characteristics and RF performances
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Karisan, Yasir. "Full-wave Electromagnetic Modeling of Electronic Device Parasitics for Terahertz Applications." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1419019102.
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Comyn, Rémi. "Développement de briques technologiques pour la co-intégration par l'épitaxie de transistors HEMTs AlGaN/GaN sur MOS silicium." Thesis, Université Côte d'Azur (ComUE), 2016. http://www.theses.fr/2016AZUR4098.
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L’intégration monolithique hétérogène de composants III-N sur silicium (Si) offre de nombreuses possibilités en termes d’applications. Cependant, gérer l’hétéroépitaxie de matériaux à paramètres de maille et coefficients de dilatation très différents, tout en évitant les contaminations, et concilier des températures optimales de procédé parfois très éloignées requière inévitablement certains compromis. Dans ce contexte, nous avons cherché à intégrer des transistors à haute mobilité électronique (HEMT) à base de nitrure de Gallium (GaN) sur substrat Si par épitaxie sous jets moléculaires (EJM) en vue de réaliser des circuits monolithiques GaN sur CMOS SiThe monolithic integration of heterogeneous devices and materials such as III-N compounds with silicon (Si) CMOS technology paves the way for new circuits applications and capabilities for both technologies. However, the heteroepitaxy of such materials on Si can be challenging due to very different lattice parameters and thermal expansion coefficients. In addition, contamination issues and thermal budget constraints on CMOS technology may prevent the use of standard process parameters and require various manufacturing trade-offs. In this context, we have investigated the integration of GaN-based high electron mobility transistors (HEMTs) on Si substrates in view of the monolithic integration of GaN on CMOS circuits
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Lancry, Ophélie. "Etude par microspectrométrie Raman de matériaux et de composants microélectroniques à base de semi-conducteurs III-V grand gap." Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2009. http://tel.archives-ouvertes.fr/tel-00460102.
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Les semi-conducteurs à base de composés III-V de type GaN présentent de nombreux avantages – liés essentiellement à leur grande bande interdite - par rapport aux semi-conducteurs traditionnels Si, ou III-V des filières GaAs. De plus, il est possible de former, comme pour les semi-conducteurs traditionnels III-V des hétérojonctions de type HEMT (High Electron Mobility Transistor) AlGaN/GaN permettant d'obtenir à la fois une forte densité de porteurs confinés à l'hétérojonction et des mobilités électroniques élevées. Ces composants sont à l'heure actuelle les candidats les plus prometteurs pour des applications hyperfréquences de puissance. Cependant, l'échauffement observé au cours du fonctionnement et les différentes étapes de réalisation des composants ont un impact anormal sur les performances intrinsèques du composant. La microspectrométrie Raman est une technique nondestructive et sans contact avec une résolution spatiale submicronique, adaptée à l'étude des HEMTs AlGaN/GaN en fonctionnement. L'utilisation de différentes longueurs d'onde excitatrices visible et UV permet de sonder les hétérostructures à différentes profondeurs de pénétration. Les informations obtenues avec cette technique d'analyse sont la composition de l'hétérostructure, les contraintes entre les différentes couches, la résistance thermique aux interfaces, la qualité cristalline des différentes couches, le dopage et le comportement thermique des différentes couches. Le développement d'un système de microspectrométrie Raman UV résolue en temps a permis d'analyser le comportement thermique transitoire des HEMTs AlGaN/GaN en fonctionnement et plus particulièrement dans la zone active du composant.
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Philippon-Martin, Audrey. "Étude d’une nouvelle filière de composants sur technologie nitrure de gallium : conception et réalisation d’amplificateurs distribués de puissance large bande à cellules cascodes en montage flip-chip et technologie MMIC." Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/862a35bd-117b-4bc6-b2a0-044747ee2ff7/blobholder:0/2007LIMO4025.pdf.
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Ces travaux de recherche se rapportent à l’étude de transistors HEMTs en Nitrure de Gallium pour l’amplification de puissance micro-onde. Une étude des caractéristiques des matériaux grand gap et plus particulièrement du GaN est réalisée afin de mettre en exergue l’adéquation de leurs propriétés pour des applications de puissance hyperfréquence telle que l’amplification large bande. Dans ce contexte, des résultats de caractérisations et modélisations électriques de composants passifs et actifs sont présentés. Les composants passifs dédiés aux conceptions de circuits MMIC sont décrits et différentes méthodes d’optimisation que ce soit au niveau électrique ou électromagnétique sont explicitées. Les modèles non linéaires de transistors impliqués dans nos conceptions sont de même détaillés. Le fruit de ces travaux concerne la conception d’amplificateurs distribués de puissance large bande à base de cellules cascode de HEMTs GaN, l’un étant reportés en flip-chip sur un substrat d’AlN, le second en technologie MMIC. La version MMIC permet d’atteindre 6. 3W sur la bande 4-18GHz à 2dB de compression. Ces résultats révèlent les fortes potentialités attendues des composants HEMTs GaNThe aim of this study is to assess the potentialities of HEMTs AlGaN/GaN transistors for RF power applications. The properties of wide band-gap materials and especially the GaN material are analysed in order to highlight their capabilities for applications to wideband power amplifiers. Modeling of passive components is explained and the design guide library on SiC substrate is implemented. Characterization results as well as linear and nonlinear simulations are presented on devices and circuits. The results of this work give concrete expression to the design of wideband power amplifiers showing a distributed architecture of cascode cells using GaN HEMTs, the first one flip-chip mounted onto an AlN substrate and the second one in MMIC technology. One MMIC version allows to obtain 6. 3W over a 4 to 18GHz bandwidth at 2dB compression input power. These results bring to light famous potentialities assigned to HEMTs GaN components
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Zborowski, Charlotte. "Characterization of deeply buried interfaces by Hard X-ray Photoelectron Spectroscopy." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC025/document.
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Cette thèse vise à améliorer la méthode d'analyse du fond continu inélastique afin de l'appliquer à des cas qui présentent un intérêt technologique. En effet, ces améliorations sont cruciales car elles portent sur des critères de précision et de gain de temps, plus particulièrement pour l’étude de dispositifs présentant plusieurs couches profondément enterrées de matériaux bien distincts. Ainsi, l'analyse du fond continu inélastique associée à la spectroscopie de photoélectrons à rayons X durs (HAXPES) présente un grand intérêt car l’HAXPES permet de sonder plus profondément dans un échantillon qu'avec la spectroscopie de photoélectrons à rayons X classique (XPS). Ce présent travail porte sur des échantillons technologiquement pertinents, principalement des transistors à haute mobilité d'électrons (HEMTs), à certaines étapes cruciales de leur processus de fabrication, tels que des recuits. Il est donc très important que ces analyses soient effectuées de manière non destructive afin de préserver les interfaces enterrées. Ce sont souvent l'emplacement de phénomènes complexes qui sont critiques pour les performances du dispositif et une meilleure compréhension est une condition préalable à l’amélioration des dispositifs. Dans ce travail, les phénomènes de diffusion en profondeur sont étudiés grâce à l’analyse du fond continu inélastique associée à l’HAXPES (en utilisant le logiciel QUASES) pour des profondeurs allant jusqu'à 60 nm. Les résultats de distribution en profondeur présentent des écarts par rapport aux mesures TEM inférieures à 5%. Le choix des paramètres d'entrée de la méthode est discuté pour une large gamme d'échantillons et des règles simples en sont issues qui rendent l'analyse réelle plus facile et plus rapide à effectuer. Enfin, il a été montré que la spectromicroscopie faite avec la technique HAXPEEM peut fournir des spectres à chaque pixel utilisables pour l’analyse du fond continu inélastique. Cela peut fournir une cartographie 3D de la distribution en profondeur des éléments de manière non-destructiveThis thesis aims at improving the inelastic background analysis method in order to apply it to technologically relevant samples. Actually, these improvements are utterly needed as they concern criteria of accuracy and time saving particularly for analysis of devices presenting deeply buried layers with different materials. For this purpose, the interest of the inelastic background analysis method is at its best when combined with hard X-ray photoelectron spectroscopy (HAXPES) because HAXPES allows to probe deeper in the sample than with conventional X-ray photoelectron spectroscopy (XPS). The present work deals with technologically relevant samples, mainly the high-electron mobility transistor (HEMT), at some crucial steps of their fabrication process as annealing. Actually, it is very important that these analyses shall be performed non-destructively in order to preserve the buried interfaces. These are often the location of complex phenomena that are critical for device performances and a better understanding is often a prerequisite for any improvement. In this thesis, the in-depth diffusion phenomena are studied with the inelastic background analysis technique (using the QUASES software) combined with HAXPES for depth up to 60 nm. The depth distribution results are determined with deviations from TEM measurements smaller than a typical value of 5%. The choice of the input parameters of the method is discussed over a large range of samples and simple rules are derived which make the actual analysis easier and faster to perform. Finally, it was shown that spectromicroscopy obtained with the HAXPEEM technique can provide spectra at each pixel usable for inelastic background analysis. This is a proof of principle that it can provide a 3D mapping of the elemental depth distribution with a nondestructive method
Denne afhandling har til formål at forbedre den uelastiske baggrundsanalysemetode til anvendelser i den til teknologiske industri. Faktisk er disse forbedringer absolut nødvendige, for at opnå nøjagtighed og tidsbesparelse, især for analyse af prøver med dybt begravede lag af forskellige materialer. Til det formål er interessen for den uelastiske baggrundsanalysemetode bedst i kombination med hård røntgenfotoelektron-spektroskopi (HAXPES), fordi HAXPES gør det muligt at probe dybere i prøven end med konventionel røntgenfotoelektron-spektroskopi (XPS). Dette arbejde beskæftiger sig med teknologisk relevante prøver, hovedsagelig høj-elektron mobilitetstransistor (HEMT), på nogle afgørende trin i deres fremstillingsproces som fx annealing. Faktisk er det meget vigtigt, at disse analyser udføres på en ikke-destruktiv måde for at bevare de begravede grænseflader. Det er ofte her de komplekse fysiske fænomener opstår, som er kritiske for fuktionaliteten, og en bedre forståelse af grænsefladerne er ofte en forudsætning for at kunne forbedre denne. I denne afhandling studeres de dybdegående diffusionsfænomener med den uelastiske baggrundsanalyse teknik (ved hjælp af QUASES software) kombineret med HAXPES for dybder op til 60 nm. Dybdestributionsresultaterne har afvigelser fra TEM-målinger mindre end en typisk værdi på 5%. Valget af input parametre for metoden er diskuteret på bagground af et stort udvalg af prøver samt omfattende simuleringer og enkle regler er udledt, hvilket gør den praktiske analyse nemmere og hurtigere at udføre. Endelig blev det vist, at spektromikroskopi opnået med HAXPEEM-teknikken kan tilvejebringe spektre ved hver enkelt pixel som kan anvendes til uelastisk baggrundsanalyse. Dette viser at i princippet kan en 3D-billeddannelse af den elementære dybdefordeling bestemmes ikke destruktivt
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Wang, Ming-Zhan, and 王明展. "Characterization of Power Semiconductor Device: GaN High Electron Mobility Transistor (HEMT)." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75689657125690554178.
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碩士健行科技大學
電子工程所
101
This research is make use of Stantaurus Workbench Integration of emiconductor device electrical and process simulation software to simulate GaN HEMT device electrical and analyze, Use GaN substrate grown on AlGaN as a barrier layer and then combining the GaN cap layer, and then to the SiN passivation treatment to complete the foundation structure of the HEMT, in this structure in a different dopant concentration, and the length of the metal electrode, electrical analysis Mohr fraction do. Discovery to the Gate and Drain spacing larger 2um, breakdown voltage relative increase nearly volts, and no obvious change in the case of changing the dopant concentration, contrary a slight deterioration of the signs, describes the this structure mainly affect the withstand voltage characteristics at the Gate and Drain spacing, The longer spacing relative higher the voltage resistance. last, in the research to identify Lsg = 2~3um, Lgd = 1~2um, the dopingdoping concentration range of 1x1014 ~1x1015 cm-3, the component breakdown voltage can be greater than 600V。
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"Modeling and Design of GaN High Electron Mobility Transistors and Hot Electron Transistors through Monte Carlo Particle-based Device Simulations." Doctoral diss., 2016. http://hdl.handle.net/2286/R.I.38356.
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abstract: In this work, the insight provided by our sophisticated Full Band Monte Carlo simulator is used to analyze the behavior of state-of-art devices like GaN High Electron Mobility Transistors and Hot Electron Transistors. Chapter 1 is dedicated to the description of the simulation tool used to obtain the results shown in this work. Moreover, a separate section is dedicated the set up of a procedure to validate to the tunneling algorithm recently implemented in the simulator. Chapter 2 introduces High Electron Mobility Transistors (HEMTs), state-of-art devices characterized by highly non linear transport phenomena that require the use of advanced simulation methods. The techniques for device modeling are described applied to a recent GaN-HEMT, and they are validated with experimental measurements. The main techniques characterization techniques are also described, including the original contribution provided by this work. Chapter 3 focuses on a popular technique to enhance HEMTs performance: the down-scaling of the device dimensions. In particular, this chapter is dedicated to lateral scaling and the calculation of a limiting cutoff frequency for a device of vanishing length. Finally, Chapter 4 and Chapter 5 describe the modeling of Hot Electron Transistors (HETs). The simulation approach is validated by matching the current characteristics with the experimental one before variations of the layouts are proposed to increase the current gain to values suitable for amplification. The frequency response of these layouts is calculated, and modeled by a small signal circuit. For this purpose, a method to directly calculate the capacitance is developed which provides a graphical picture of the capacitative phenomena that limit the frequency response in devices. In Chapter 5 the properties of the hot electrons are investigated for different injection energies, which are obtained by changing the layout of the emitter barrier. Moreover, the large signal characterization of the HET is shown for different layouts, where the collector barrier was scaled.Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2016
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林以寬. "Simulation for the high frequency high electron mobility transistor (HEMT) design." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/39145846952527677519.
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碩士逢甲大學
電子工程學系
102
We constructed the high electron mobility transistors by TCAD (Technology Computer Aided Design).The process of the mask design, deposited material and carrier concentration can be preciously confirmed to the actual process and effect. Moreover, the DC performances and the analyses of high-frequency small-signal signal were simulated in different respects. There are various HEMT models in this thesis. We observed that the gate voltage for double and single carrier supply layers devices might change the saturated current of channel. The saturated current was changed from 400 mA/mm to 36 mA/mm. The series resistances of source and drain would also affect the channel current. We also reduced the channel length and then investigated the high-frequency characteristics with the short-channel effects. And the cutoff frequency of short channel is 263.18 GHz. It is 24GHz higher than the cutoff frequency of long channel. Eventually, the effects on electrical properties caused by changing the ingredients of indium inside the channel were studied. The current gain is up to 46.46 dB and the power gain is 35.1 dB. The bandgap of capping material on both sides of channel with different lattice structure also were simulated to view the properties of the devices.. The TCAD combining complete physical theorems and mathematical formulas gives the whole pictures for the simulated devices. We can know the behaviors including the electron field of those devices by providing input signal quickly and precisely from block program in the TCAD. All qualities of those device were realized without fabricating a solid device.
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"TEM Characterization of Electrically Stressed High Electron Mobility Transistors." Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.16023.
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abstract: High electron mobility transistors (HEMTs) based on Group III-nitride heterostructures have been characterized by advanced electron microscopy methods including off-axis electron holography, nanoscale chemical analysis, and electrical measurements, as well as other techniques. The dissertation was organized primarily into three topical areas: (1) characterization of near-gate defects in electrically stressed AlGaN/GaN HEMTs, (2) microstructural and chemical analysis of the gate/buffer interface of AlN/GaN HEMTs, and (3) studies of the impact of laser-liftoff processing on AlGaN/GaN HEMTs. The electrical performance of stressed AlGaN/GaN HEMTs was measured and the devices binned accordingly. Source- and drain-side degraded, undegraded, and unstressed devices were then prepared via focused-ion-beam milling for examination. Defects in the near-gate region were identified and their correlation to electrical measurements analyzed. Increased gate leakage after electrical stressing is typically attributed to "V"-shaped defects at the gate edge. However, strong evidence was found for gate metal diffusion into the barrier layer as another contributing factor. AlN/GaN HEMTs grown on sapphire substrates were found to have high electrical performance which is attributed to the AlN barrier layer, and robust ohmic and gate contact processes. TEM analysis identified oxidation at the gate metal/AlN buffer layer interface. This thin a-oxide gate insulator was further characterized by energy-dispersive x-ray spectroscopy and energy-filtered TEM. Attributed to this previously unidentified layer, high reverse gate bias up to −30 V was demonstrated and drain-induced gate leakage was suppressed to values of less than 10−6 A/mm. In addition, extrinsic gm and ft * LG were improved to the highest reported values for AlN/GaN HEMTs fabricated on sapphire substrates. Laser-liftoff (LLO) processing was used to separate the active layers from sapphire substrates for several GaN-based HEMT devices, including AlGaN/GaN and InAlN/GaN heterostructures. Warpage of the LLO samples resulted from relaxation of the as-grown strain and strain arising from dielectric and metal depositions, and this strain was quantified by both Newton's rings and Raman spectroscopy methods. TEM analysis demonstrated that the LLO processing produced no detrimental effects on the quality of the epitaxial layers. TEM micrographs showed no evidence of either damage to the ~2 μm GaN epilayer generated threading defects.Dissertation/Thesis
Ph.D. Physics 2012
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LIU, TANG-JIE, and 劉堂傑. "Analysis and simulation of the high electron mobility field effect transistors (HEMT." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/68211321540583691086.
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"Modeling Reliability of Gallium Nitride High Electron Mobility Transistors." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.17732.
Full textAbstract:
abstract: This work is focused on modeling the reliability concerns in GaN HEMT technology. The two main reliability concerns in GaN HEMTs are electromechanical coupling and current collapse. A theoretical model was developed to model the piezoelectric polarization charge dependence on the applied gate voltage. As the sheet electron density in the channel increases, the influence of electromechanical coupling reduces as the electric field in the comprising layers reduces. A Monte Carlo device simulator that implements the theoretical model was developed to model the transport in GaN HEMTs. It is observed that with the coupled formulation, the drain current degradation in the device varies from 2%-18% depending on the gate voltage. Degradation reduces with the increase in the gate voltage due to the increase in the electron gas density in the channel. The output and transfer characteristics match very well with the experimental data. An electro-thermal device simulator was developed coupling the Monte Caro-Poisson solver with the energy balance solver for acoustic and optical phonons. An output current degradation of around 2-3 % at a drain voltage of 5V due to self-heating was observed. It was also observed that the electrostatics near the gate to drain region of the device changes due to the hot spot created in the device from self heating. This produces an electric field in the direction of accelerating the electrons from the channel to surface states. This will aid to the current collapse phenomenon in the device. Thus, the electric field in the gate to drain region is very critical for reliable performance of the device. Simulations emulating the charging of the surface states were also performed and matched well with experimental data. Methods to improve the reliability performance of the device were also investigated in this work. A shield electrode biased at source potential was used to reduce the electric field in the gate to drain extension region. The hot spot position was moved away from the critical gate to drain region towards the drain as the shield electrode length and dielectric thickness were being altered.Dissertation/Thesis
Ph.D. Electrical Engineering 2013