To see the other types of publications on this topic, follow the link: HEMT.
Dissertations / Theses on the topic 'HEMT'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'HEMT.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Bolt, Edward Lawrence. "5-aminolaevulinic acid synthase isozymes of Rhodobacter sphaeroides : cloning, expression of structural genes, purification and characterisation of E. coli." Thesis, Queen Mary, University of London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336440.
Full text
2
Khalil, Ibrahim. "Intermodulation distortion in GaN HEMT." Göttingen Cuvillier, 2009. http://d-nb.info/1000063275/04.
Full text
3
Lundskog, Anders. "Characterization of AlGaN HEMT structures." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9729.
Full textAbstract:
During the last decade, AlGaN High Electron Mobility Transistors (HEMTs) have been intensively studied because their fundamental electrical properties make them attractive for highpower microwave device applications. Despite much progress, AlGaN HEMTs are far from fully understood and judged by the number of published papers the understanding of advanced structures is even poorer. This work is an exploration of the electrical and structural properties of advanced HEMT structure containing AlN exclusionlayer and double heterojunctions. These small modifications had great impact on the electrical properties.
In this work, AlGaN HEMT structures grown on SiC substrates by a hot-wall MOCVD have been characterized for their properties using optical microscopy, scanning electron microscopy, transmission electron microscopy, capacitance/voltage, eddy-current resistivity, and by homebuilt epi-thickness mapping equipment.
A high electron mobility of 1700 [cm2/Vs] was achieved in an AlN exclusion-layer HEMT. A similar electron mobility of 1650 [cm2/Vs] was achieved in a combination of a double heterojunction and exclusion-layer structure. The samples had approximately the same electron mobility but with a great difference: the exclusion-layer version gave a sheet carrier density of 1.58*1013 [electrons/cm2] while the combination of double heterojunction and exclusion-layer gave 1.07*1013 [electrons/cm2]. A second 2DEG was observed in most structures, but not all, but was not stable with time.
The structures we grew during this work were also simulated using a one-dimensional Poisson-Schrödinger solver and the simulated electron densities were in fairly good agreement with the experimentally obtained. III-nitride materials, the CVD concept, and the onedimensional solver are shortly explained.
4
Sjue, Espen. "Modellering av HEMT Mikrobølge effekttransistor." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10311.
Full textAbstract:
Arbeidet med oppgaven gikk ut på å studere ulike kalibreringsmetoder for nettverksanalysator, utarbeidelse av testkort med kalibreringskomponenter. Målinger av DC- og AC-oppførselen til transistoren, for så å benytte programmet Agilent ADS og TOM-modellen til å lage en datamodell for denne transistoren. Det ble også utarbeidet en metode for hvordan man kan gå frem for å utarbeide en datamodell for en transistor. Arbeidet resulterte i en transistormodell som viste tilsynelatende gode egenskaper, og en metode for utarbeidelse av transistormodeller som fungerte godt for den utvalgte transistoren i denne oppgaven.
5
Buchanan, Neil Bryans. "Phase locked millimetre wave HEMT oscillators." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322829.
Full text
6
Malik, Adil Mahmood. "Technology and physics of gate recessed GaN AlGaN FETs." [S.l. : s.n.], 2003. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-30157.
Full text
7
Aroshvili, Giorgi. "GaN HEMT and MMIC Design and Evaluation." Thesis, University of Gävle, Department of Technology and Built Environment, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-3085.
Full textAbstract:
Gallium Nitride based devices due to their inherent material properties are considered as one of the most promising devices to realize high power, high frequency transistors with lower power consumption in next-generation applications. Although the technology has been studied since early 1970s, there is still a vast room and expectations in its yet unachieved findings. In present work the GaN technology is explored and state-of-the-art studies of GaN based HEMTs and their application in MMICs are presented. Different designs are presented and evaluated and the results are reported. In particular the HEMT performance is studied in terms of DC in addition to large signal conditions, where the device’s performance becomes function of power levels it is driven with. The peculiarities and challenges of building an automated Load-Pull setup are outlined and analysis for further improvements is presented.
8
Navarrete, Moreno Francisco José. "Caracterización de Transistores Hemt en Banda Q." Tesis, Universidad de Chile, 2011. http://www.repositorio.uchile.cl/handle/2250/104301.
Full textAbstract:
Este trabajo de título tiene como objetivo diseñar y construir un sistema de caracterización de transistores HEMT. Este sistema tiene como n determinar el comportamiento de transistores candidatos a ser utilizados en el diseño de ampli cadores de bajo ruido para receptores de antenas radioastronomicas que operen en Banda 1 del proyecto ALMA.
Como parte de este sistema se diseñaron y construyeron dos módulos, un módulo Bias Tee y un sistema de calibración TRL. El módulo Bias Tee permite acoplar, por un mismo canal, la señal proveniente del VNA y la polarización para entregarlas al transistor. El módulo de calibración TRL permite descontar de la medicion de parámetros S del transistor, el efecto del resto de los elementos que forman el sistema de caracterización. Además, se desarrolló un software que a partir de los datos obtenidos del transistor calcula sus parámetros S.
Al realizar las mediciones del módulo Bias Tee y del sistema de calibración, estas diferían del comportamiento que mostraban las simulaciones. En el caso del Bias Tee se encontró que la mayor parte de la señal incidente en el módulo se refleja. En el caso del sistema de calibración, se genera una calibración exitosa pero altamente sensible a las modi caciones en el montaje, lo que no permite obtener una calibración estable para medir el transistor.
Al analizar los problemas descritos, se identi có que el elemento común en ambos módulos son los conectores 2.4 mm que se utilizan a la entrada y salida de ambos módulos. Se encontró que el montaje de estos conectores no es el más idóneo. Como alternativa, se estudia un diseño alternativo llamado montaje de adaptación. Las simulaciones indican que las reflexiones son menores a -20 dB, lo que representa mejores resultados que el montaje simple.
En conclusión, este trabajo ha permitido identi car problemas no previstos en la caracterización del transistor de prueba. Se espera que al cambiar el método de montaje de los conectores 2.4 mm el sistema diseñado funcione correctamente.
9
Waldron, Niamh 1974. "InGaAs self-aligned HEMT for logic applications." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/44293.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 123-132).
As CMOS scaling approaches the end of the roadmap it has become a matter of great urgency to explore alternative options to conventional Si devices for logic applications. The high electron mobilities of III-V based compounds makes them an attractive option for use as a channel material. Of these materials, InGaAs offers the best balance between a mature technology and high mobility. InGaAs high electron mobility transistors (HEMTs) have already been shown to hold great promise for logic devices but they are typically not self-aligned nor enhancement mode and as such are not suitable for scaled VLSI applications. In this work a novel self-aligned device architecture for InGaAs HEMT devices is proposed and demonstrated. The key feature of the process is a non-alloyed a W ohmic layer that is separated from the gate by means of an air spacer. The gate to source metal distance is reduced to 60 nm, a 20x improvement over conventional designs where the source to drain distance is typically 1.5 to 2 /Lm. A detailed analysis of the source resistance was carried out and the heterojunction barrier resistance was determined to be the dominant resistance component. Two methods of changing the device threshold voltage are investigated. In the first F is used to passivate Si donors in the insulator layer. In the second the insulator is thinned by means of a dry etch. No degradation of the source resistance was observed using this method, which is an improvement over previous results using wet chemical etching. A 90 nm self-aligned enhancement-mode device with a vertically scaled insulator thickness of 5 nm was fabricated. The device has outstanding logic figures of merit with a VT of 60 mV, g, of 1.3 S/mm, SS of 71 mV/dec, DIBL of 55 mV/V and an I,/Ileak ratio of 2x103.
(cont.) These values are outstanding when compared to state of-the-art Si devices. The relatively low In/Ileak ratio is a consequence of operating a Schottky gate device in enhancement mode. Ultimately a high-k gate dielectric solution will be required.
by Niamh Waldron.
Ph.D.
10
Zhang, Guohao. "Optical control of millimetre-wave HEMT oscillators." Thesis, University of Leeds, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.755765.
Full text
11
Astre, Guilhem. "Fiabilité des dispositifs HEMT en technologie GaN." Phd thesis, Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1980/.
Full textAbstract:
Le point sensible inhérent à la commercialisation d'une technologie émergente est la maturité des processus utilisés garantissant la qualité de l'épitaxie, de la métallisation du contact de grille ou encore de la passivation. Les études de fiabilité s'imposent alors comme un aspect indissociable de la maturation de la technologie. En ce sens, les composants à grands gap représentent un réel problème car les outils classiques de caractérisation ne sont pas toujours adaptés aux contraintes imposées (thermiques, RF, DC. . . ). Dans cette thèse, nous détaillons une technique originale pour améliorer la fiabilité des dispositifs AlGaN/GaN par diffusion de deutérium et nous présentons l'ensemble des résultats issus des campagnes de mesures menées à l'aide des outils disponibles sur des lots de composants issus des filières UMS et TRT. Les principaux résultats concernent les mesures de bruit basse fréquence, la caractérisation électrique, la spectroscopie des pièges profonds et les mesures en température de courant de grille qui ont été réalisés sur des lots de composants témoins et ayant subi différents types de stressReliability in GaN based devices still motivates numerous studies because the involved degradation mechanisms are different from that in III-V narrow bandgap devices. Direct investigations on high electron mobility transistors (HEMT) are performed with low frequency noise (LFN) measurements, pulsed electrical characterization and deep level transient spectroscopy. The first part of this thesis deals with generalities on AlGaN/GaN High electron mobility transistors and their technological particularities. The second part deals with the presentation of the diagnostic tools used in this study. A low frequency noise bench developed in LAAS-CNRS allowing measurements from few hertz up to 1 MHz is described, an original method of electrical pulsed characterization has and current deep level spectroscopy bench. In the third part of this study, low frequency noise is used to assess effects of deuterium (H+ ions) in diffusion condition on the robustness of 0. 25 *2*75 µm² gate area AlGaN/GaN high electron mobility transistors (HEMT) grown on Si substrate. H+ Ions are diffused from the above AlGaN/GaN layer through the AlGaN/GaN interface and GaN layer, notably under the gated channel where the defects are located. In the fourth part, undoped AlGaN/GaN devices grown on silicon substrate have been stressed at a junction temperature of 175°C. Gate-lag and drain-lag measurements method have been performed versus different quiescent bias points and under different pulse conditions. This method allows the discrimination of each lag phenomenon as well as the thermal contribution. Thus it is possible to track and model the trapping mechanisms versus bias conditions. This electrical modeling is completed with LFN measurements and deep level transient spectroscopy, which is largely used for reliability investigations
12
Astre, Guilhem. "Fiabilité des dispositifs HEMT en technologie GaN." Phd thesis, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00767154.
Full textAbstract:
Le point sensible inhérent à la commercialisation d'une technologie émergente est la maturité des processus utilisés garantissant la qualité de l'épitaxie, de la métallisation du contact de grille ou encore de la passivation. Les études de fiabilité s'imposent alors comme un aspect indissociable de la maturation de la technologie. En ce sens, les composants à grands gap représentent un réel problème car les outils classiques de caractérisation ne sont pas toujours adaptés aux contraintes imposées (thermiques, RF, DC...). Dans cette thèse, nous détaillons une technique originale pour améliorer la fiabilité des dispositifs AlGaN/GaN par diffusion de deutérium et nous présentons l'ensemble des résultats issus des campagnes de mesures menées à l'aide des outils disponibles sur des lots de composants issus des filières UMS et TRT. Les principaux résultats concernent les mesures de bruit basse fréquence, la caractérisation électrique, la spectroscopie des pièges profonds et les mesures en température de courant de grille qui ont été réalisés sur des lots de composants témoins et ayant subi différents types de stress.
13
Kaganjo, James Chege. "Purification and Characterization of Rhodobacter sphaeroides 2.4.1 HemT and Comparison with HemA Isoenzyme." Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1371650426.
Full text
14
Cibie, Anthony. "Substrats innovants pour des composants de puissance à base de GaN." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI014/document.
Full textAbstract:
A l’heure actuelle, le marché de l’électronique de puissance est dominé par les composants silicium. Néanmoins, de nouveaux matériaux comme le nitrure de gallium ont émergé dans ce domaine grâce à leurs propriétés intéressantes. Ces nouveaux composants sont principalement réalisés sur des substrats silicium ce qui induit certaines problématiques lors de leur fabrication ou au niveau de leurs performances. Nous nous sommes intéressés dans cette thèse à des approches d’un point de vue du substrat dans l’objectif de résoudre ces problématiques. Ce travail a permis notamment de mettre en place une succession de procédés technologiques afin de remplacer le substrat silicium de fabrication par d’autres matériaux pour améliorer les performances de ces composants. Cette approche a notamment permis de transférer des composants fonctionnels sur un substrat cuivre. L’impact électrique et thermique du remplacement du substrat initial par un nouveau matériau a été étudié. Ce travail ouvre ainsi la voie du report de composants en nitrure de gallium réalisés sur des substrats silicium de diamètre 200 mm ou plusNew materials such as gallium nitride (GaN) emerge as promising candidates for power electronics. The current trend is to fabricate the AlGaN/GaN power devices directly on (111) silicon substrates. It makes the expitaxy of the GaN challenging and affects the device performances. In this work, we focus on substrate approaches to solve these problems. A transfer process was developed to replace the silicon substrate by another material to enhance electrical performances of the devices. Especially, GaN devices were transferred on copper substrates without electrical degradation. Electrical and thermal characterizations were performed to study the impact of the transfer. This work offers a first approach on the transfer of GaN devices from 8 or even 12 inches silicon substrates
15
Gonçalves, Cristiano Ferreira. "GaN HEMT transistors characterization for non–linear modelling." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/21677.
Full textAbstract:
Mestrado em Engenharia Eletrónica e TelecomunicaçõesUltimamente, as redes de telecomunicações móveis estão a exigir cada vez maiores taxas de transferência de informação. Com este aumento, embora sejam usados códigos poderosos, também aumenta a largura de banda dos sinais a transmitir, bem como a sua frequência. A maior frequência de operação, bem como a procura por sistemas mais eficientes, tem exigido progressos no que toca aos transístores utilizados nos amplificadores de potência de radio frequência (RF), uma vez que estes são componentes dominantes no rendimento de uma estação base de telecomunicações. Com esta evolução, surgem novas tecnologias de transístores, como os GaN HEMT (do inglês, Gallium Nitride High Electron Mobility Transistor). Para conseguir prever e corrigir certos efeitos dispersivos que afetam estas novas tecnologias e para obter o amplificador mais eficiente para cada transístor usado, os projetistas de amplificadores necessitam cada vez mais de um modelo que reproduza fielmente o comportamento do dispositivo. Durante este trabalho foi desenvolvido um sistema capaz de efetuar medidas pulsadas e de elevada exatidão a transístores, para que estes não sejam afetados, durante as medidas, por fenómenos de sobreaquecimento ou outro tipo de fenómenos dispersivos mais complexos presentes em algumas tecnologias. Desta forma, será possível caracterizar estes transístores para um estado pré determinado não só de temperatura, mas de todos os fenómenos presentes. Ao longo do trabalho vai ser demostrado o projeto e a construção deste sistema, incluindo a parte de potência que será o principal foco do trabalho. Foi assim possível efetuar medidas pulsadas DC-IV e de parâmetros S (do inglês, Scattering) pulsados para vários pontos de polarização. Estas últimas foram conseguidas á custa da realização de um kit de calibração TRL. O interface gráfico com o sistema foi feito em Matlab, o que torna o sistema mais fácil de operar. Com as medidas resultantes pôde ser obtida uma primeira análise acerca da eficiência, ganho e potência máxima entregue pelo dispositivo. Mais tarde, com as mesmas medidas pôde ser obtido um modelo não linear completo do dispositivo, facilitando assim o projeto de amplificadores.
Lately, the wireless networks should feature higher data rates than ever. With this rise, although very powerful codification schemes are used, the bandwidth of the transmitted signals is rising, as well as the frequency. Not only caused by this rise in frequency, but also by the growing need for more efficient systems, major advances have been made in terms of Radio Frequency (RF) Transistors that are used in Power Amplifiers (PAs), which are dominant components in terms of the total efficiency of base stations (BSS). With this evolution, new technologies of transistors are being developed, such as the Gallium Nitride High Electron Mobility Transistor (GaN HEMT). In order to predict and correct some dispersive effects that affect these new technologies and obtain the best possible amplifier for each different transistor, the designers are relying more than ever in the models of the devices. During this work, one system capable of performing very precise pulsed measurements on RF transistors was developed, so that they are not affected, during the measurements, by self-heating or other dispersive phenomena that are present in some technologies. Using these measurements it was possible to characterize these transistors for a pre-determined state of the temperature and all the other phenomena. In this document, the design and assembly of the complete system will be analysed, with special attention to the higher power component. It will be possible to measure pulsed Direct Current Current-Voltage (DC-IV) behaviour and pulsed Scattering (S) parameters of the device for many different bias points. These latter ones were possible due to the development of one TRL calibration kit. The interface with the system is made using a graphical interface designed in Matlab, which makes it easier to use. With the resulting measurements, as a first step analysis, the maximum efficiency, gain and maximum delivered power of the device can be estimated. Later, with the same measurements, the complete non-linear model of the device can be obtained, allowing the designers to produce state-of-art RF PAs.
16
Fontserè, Recuenco Abel. "Advanced AlGaN/GaN HEMT technology, design, fabrication and characterization." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/129098.
Full textAbstract:
Nowadays, the microelectronics technology is based on the mature and very well established silicon (Si) technology. However, Si exhibits some important limitations regarding its voltage blocking capability, operation temperature and switching frequency. In this sense, Gallium Nitride (GaN)-based high electron mobility transistors (HEMTs) devices have the potential to make this change possible. The unique combination of the high-breakdown field, the high-channel electron mobility of the two dimensional electron gas (2DEG), and high-temperature of operation has attracted enormous interest from social, academia and industry and in this context this PhD dissertation has been made. This thesis has focused on improving the device performance through the advanced design, fabrication and characterization of AlGaN/GaN HEMTs, primarily grown on Si templates.
The first milestone of this PhD dissertation has been the establishment of a know-how on GaN HEMT technology from several points of view: the device design, the device modeling, the process fabrication and the advanced characterization primarily using devices fabricated at Centre de Recherche sur l'Hétéro-Epitaxie (CRHEA-CNRS) (France) in the framework of a collaborative project. In this project, the main workhorse of this dissertation was the explorative analysis performed on the AlGaN/GaN HEMTs by innovative electrical and physical characterization methods. A relevant objective of this thesis was also to merge the nanotechnology approach with the conventional characterization techniques at the device scale to understand the device performance.
A number of physical characterization techniques have been imaginatively used during this PhD determine the main physical parameters of our devices such as the morphology, the composition, the threading dislocations density, the nanoscale conductive pattern and others. The conductive atomic force microscopy (CAFM) tool have been widely described and used to understand the conduction mechanisms through the AlGaN/GaN Ohmic contact by performing simultaneously topography and electrical conductivity measurements. As it occurs with the most of the electronic switches, the gate stack is maybe the critical part of the device in terms of performance and longtime reliability. For this reason, how the AlGaN/GaN HEMT gate contact affects the overall HEMT behaviour by means of advanced characterization and modeling has been intensively investigated.
It is worth mentioning that the high-temperature characterization is also a cornerstone of this PhD. It has been reported the elevated temperature impact on the forward and the reverse leakage currents for analogous Schottky gate HEMTs grown on different substrates: Si, sapphire and free-standing GaN (FS-GaN). The HEMT' forward-current temperature coefficients (T^a) as well as the thermal activation energies have been determined in the range of 25-300 ºC. Besides, the impact of the elevated temperature on the Ohmic and gate contacts has also been investigated.
The main results of the gold-free AlGaN/GaN HEMTs high-voltage devices fabricated with a 4 inch Si CMOS compatible technology at the clean room of the CNM in the framework of the industrial contract with ON semiconductor were presented. We have shown that the fabricated devices are in the state-of-the-art (gold-free Ohmic and Schottky contacts) taking into account their power device figure-of-merit ((VB^2)/Ron) of 4.05×10^8 W/cm^2. Basically, two different families of AlGaN/GaN-on-Si MIS-HEMTs devices were fabricated on commercial 4 inch wafers: (i) using a thin ALD HfO2 (deposited on the CNM clean room) and (ii) thin in-situ grown Si3N4, as a gate insulator (grown by the vendor). The scientific impact of this PhD in terms of science indicators is of 17 journal papers (8 as first author) and 10 contributions at international conferences.
17
Duff, Christopher Iain. "Tractable and scalable CAD model for filtronic HEMT devices." Thesis, University of Manchester, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556620.
Full text
18
Moran, David A. J. "Self-aligned short gate length III-V HEMT technology." Thesis, University of Glasgow, 2004. http://theses.gla.ac.uk/6577/.
Full textAbstract:
This thesis presents a ne- approach to the fabrication of short gate length HI-V High Electron Mobility Transistors (HEMTs) that reduces the impact of external parasitic elements, and in particular access resistances, upon device performance. This was approached through the development of a self-aligned T-gate process with non-annealed ohmic contacts. The process was used to fabricate both GaAs pseudomorphic HEMT and subsequently lattice matched InP devices. In addition, a new selective recess etch was developed for cap layers containing indium. Characterisation of the self-aligned GaAs pHEMT devices indicated good RF performance with fT = 137GHz and fmax = 182GHz for devices of 120nm gate length, although DC performance was found to be restricted by the unoptimised non-annealed ohmic process. Analysis of the operation of the GaAs pHEMT devices led to the design and growth of an InP material structure incorporating double delta doping to minimise the non-annealed ohmic contact resistance. Using this optimised structure, standard and self-aligned HEMT devices with gates of length 120nm and 70nm were fabricated for comparison. The benefits and limitations of the self-aligned process were highlighted by comparing the performance of the self-aligned and standard devices. The self-aligned 120nm devices had fT = 220GHz and fmax = 255GHz, which rose to fT = 270GHz and fmax = 300GHz for the 70nm devices. Transconductance figures of up to 1500mS/mm were extracted for both. It is concluded that the self-aligned process, although beneficial to device performance at the 120nm, and to a lesser degree the 70nm node, would begin to degrade performance at reduced gate lengths due to increased parasitic gate capacitances. The non-annealed ohmic technology developed in this work provides a route that minimises parasitic resistances and increases performance without the increased parasitic gate capacitances associated with a self-aligned gate approach. A possible solution for the minimisation of parasitic gate capacitances using a self-aligned approach is proposed.
19
Saini, Kanika. "Linearity Enhancement of High Power GaN HEMT Amplifier Circuits." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/94361.
Full textAbstract:
Gallium Nitride (GaN) technology is capable of very high power levels but suffers from high non-linearity. With the advent of 5G technologies, high linearity is in greater demand due to complex modulation schemes and crowded RF (Radio Frequency) spectrum. Because of the non-linearity issue, GaN power amplifiers have to be operated at back-off input power levels. Operating at back-off reduces the efficiency of the power amplifier along-with the output power. This research presents a technique to linearize GaN amplifiers. The linearity can be improved by splitting a large device into multiple smaller devices and biasing them individually. This leads to the cancellation of the IMD3 (Third-order Intermodulation Distortion) components at the output of the FETs and hence higher linearity performance.
This technique has been demonstrated in Silicon technology but has not been previously implemented in GaN. This research work presents for the first time the implementation of this technique in GaN Technology.
By the application of this technique, improvement in IMD3 of 4 dBc has been shown for a 0.8-1.0 GHz PA (Power Amplifier), and 9.5 dBm in OIP3 (Third-order Intercept Point) for an S-Band GaN LNA, with linearity FOM (IP3/DC power) reaching up to 20.
Large-signal simulation and analysis have been done to demonstrate linearity improvement for two parallel and four parallel FETs. A simulation methodology has been discussed in
detail using commercial CAD software. A power sampler element is used to compute the IMD3 currents coming out of various FETs due to various bias currents. Simulation results show by biasing one device in Class AB and others in deep Class AB, IMD3 components of parallel FETs can be made out of phase of each other, leading to cancellation and improvement in linearity. Improvement up to 20 dBc in IMD3 has been reported through large-signal simulation when four parallel FETs with optimum bias were used.
This technique has also been demonstrated in simulation for an X-Band MMIC PA from 8-10 GHz in GaN technology. Improvements up to 25-30 dBc were shown using the technique of biasing one device with Class AB and other with deep class AB/class B. The proposed amplifier achieves broadband linearization over the entire frequency compared to state-of-the-art PA's. The linearization technique demonstrated is simple, straight forward, and low cost to implement. No additional circuitry is needed. This technique finds its application in high dynamic range RF amplifier circuits for communications and sensing applications.Doctor of Philosophy
Power amplifiers (PAs) and Low Noise Amplifiers (LNAs) form the front end of the Radio Frequency (RF) transceiver systems. With the advent of complex modulation schemes, it is becoming imperative to improve their linearity. Through this dissertation, we propose a technique for improving the linearity of amplifier circuits used for communication systems. Meanwhile, Gallium Nitride (GaN) is becoming a technology of choice for high-power amplifier circuits due to its higher power handling capability and higher breakdown voltage compared with Gallium Arsenide (GaAs), Silicon Germanium (SiGe) and Complementary Metal-Oxide-Semiconductor (CMOS) technologies. A circuit design technique of using multiple parallel GaN FETs is presented. In this technique, the multiple parallel FETs have independently controllable gate voltages. Compared to a large single FET, using multiple FETs and biasing them individually helps to improve the linearity through the cancellation of nonlinear distortion components. Experimental results show the highest linearity improvement compared with the other state-of-the-art linearization schemes. The technique demonstrated is the first time implementation in GaN technology. The technique is a simple and cost-effective solution for improving the linearity of the amplifier circuits. Applications include base station amplifiers, mobile handsets, radars, satellite communication, etc.
20
Liu, Zhengyang. "Characterization and Failure Mode Analysis of Cascode GaN HEMT." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49580.
Full textAbstract:
Recent emerging gallium nitride (GaN) high electron mobility transistor (HEMT) is expected to be a promising candidate for high frequency power conversion techniques. Due to the advantages of the material, the GaN HEMT has a better figure of merit (FOM) compared to the state-of-the-art silicon (Si) power metal oxide silicon field effect transistor (MOSFET), which allows the GaN HEMT to switch with faster transition and lower switching loss. By applying the GaN HEMT in a circuit design, it is possible to achieve high frequency, high efficiency, and high density power conversion at the same time.
To characterize the switching performance of the GaN HEMT, an accurate behavior-level simulation model is developed in this thesis. The packaging related parasitic inductance, including both self-inductance and mutual-inductance, are extracted based on finite element analysis (FEA) methods. Then the accuracy of the simulation model is verified by a double-pulse tester, and the simulation results match well with experiment in terms of both device switching waveform and switching energy.
Based on the simulation model, detailed loss breakdown and loss mechanism analysis are made. The cascode GaN HEMT has high turn-on loss due to the body diode reverse recovery of the low voltage Si MOSFET and the common source inductance (CSI) of the package; while the turn-off loss is extremely small attributing to the cascode structure.
With this unique feature, the critical conduction mode (CRM) soft switching technique are applied to reduce the dominant turn on loss and increase converter efficiency significantly. The switching frequency is successfully pushed to 5MHz while maintaining high efficiency and good thermal performance.
Traditional packaging method is becoming a bottle neck to fully utilize the advantages of GaN HEMT. So an investigation of the package influence on the cascode GaN HEMT is also conducted. Several critical parasitic inductors are identified, which cause high turn on loss and high parasitic ringing which may lead to device failure. To solve the issue, the stack-die package is proposed to eliminate all critical parasitic inductors, and as a result, reducing turn on loss by half and avoiding potential failure mode of the cascode GaN device effectively.
Utilizing the proposed stack-die package and ZVS soft switching, the GaN HEMT high frequency, high efficiency, and high density power conversion capability can be further extended to a higher level.Master of Science
21
Cao, Menglin. "The development of silicon compatible processes for HEMT realisation." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6803/.
Full textAbstract:
Compound semiconductor (III-V) devices are crucially important in a range of RF/microwave applications. High Electron Mobility Transistors (HEMTs), as the best low noise high frequency compound semiconductor devices, have been utilised in various applications at microwave and mm-wave frequencies such as communications, imaging, sensing and power. However, silicon based manufacturing will always be the heart of the semiconductor industry. III-V devices are conventionally fabricated using gold-based metallisation and lift off processes, which are incompatible with silicon manufacturing processes based on blanket metal or dielectric deposition and subtractive patterning by dry etching techniques. Therefore, the challenge is to develop silicon compatible processes for the realisation of compound semiconductor devices, whilst not compromising the device performance. In this work, silicon compatible processes for HEMT realisation have been developed, including the demonstration of a copper-based T-gate with the normalised DC resistance of 42 Ω/mm, and the presentation of a gate-first process flow which can incorporate the copper-based T-gate. The copper electroplating process for fabricating T-gate head with the maximum width of 2.5 µm, low damage inductively coupled plasma molybdenum etching process for realising T-gate foot with the minimum footprint of 30 nm, and the full gate-first process flow with non-annealed ohmic contact are described in detail. In addition, this thesis also describes the fabrication and characterisation of a 60 nm footprint gold-based T-gate HEMT realised by conventional III-V processes, yielding a cutoff frequency fT of 183GHz and maximum oscillation frequency fmax of 156GHz. In the comparison between these two types of HEMT, it is anticipated that a HEMT with the copper-based T-gate would not only have a larger maximum frequency of oscillation fmax, but also an easier incorporation into a silicon based manufacturing fab in terms of process technologies, than a HEMT with the gold-based T-gate.
22
Danesin, Francesca. "Stress, Overstress and Strain on AlGaN/GaN HEMT Devices." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425693.
Full textAbstract:
Defence radar and wireless communication systems have a drastic need for increased rf performance for high power, high efficiency, high linearity and low-cost monolithic amplifiers operating in the 1-40 GHz frequency range. Semiconductor devices based on Silicon (Si) or Gallium Arsenide (GaAs) are currently used for the fabrication of communication systems but they are not able to deal with the continuous increase in demand for microwave power performances: those devices are very close to their limit, working with a poor efficiency and requiring large cooling systems. Therefore Gallium nitride-based devices are becoming extremely attractive for a wide range of applications, from optoelectronics to power electronics. In particular, High Electron Mobility Transistors (HEMT) are emerging as a key technology for rf and microwave amplifiers, but their stability and reliability is still one of the main issue that has to be solved in order to achieve production level quality devices.I sistemi di comunicazione di ultima generazione, basati su amplificatori che operano a frequenze tra gli 1 ed i 40 GHz, necessitano di prestazioni rf sempre più spinte per quel che riguarda la potenza, l’efficienza, la linearità ed il basso costo. I semiconduttori basati sul Silicio (Si) o sull’ Arseniuro di Gallio (GaAs) che sono abitualmente utilizzati per la costruzione di sistemi di comunicazione non sono in grado di soddisfare la domanda continua e crescente di prestazioni di potenza alle microonde. Questo tipo di dispositivi sono vicini al limite delle proprie prestazioni, lavorano con bassa efficienza e richiedono sistemi di raffreddamento di grandi dimensioni. I dispositivi basati su Nitruro di Gallio stanno quindi diventando interessanti per un gran numero di applicazioni: dalla optoelettronica all’ elettronica di potenza. In particolare i transistor ad alta mobilità elettronica (HEMT) si sono rivelati promettenti per gli amplificatori a microonde ma la loro stabilità e affidabilità sono ancora uno dei problemi da risolvere per ottenere un prodotto commercializzabile e pronto per il mercato.
23
Duran, Halit C. Duran Halit Celâleddin. "High performance InP-based HEMTs with dry etched gate recess /." [S.l.] : [s.n.], 1998. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=12900.
Full text
24
Neuburger, Martin. "Entwurf und Technologie von GaN-Heterostruktur FETs für hohe Leistung." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-57224.
Full text
25
Xiao, Xiao Mr. "Purification and Characterization of Rhodobacter sphaeroides Polyhistidine-tagged HemA and Comparison with Purified Polyhistidine-tagged HemT." Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1371650467.
Full text
26
Someswaran, Preethi. "Large Signal Modelling of AlGaN/GaN HEMT for Linearity Prediction." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440392889.
Full text
27
Sadek-Hage, Chehade Sawsan. "Microcapteurs hybrides et monolithiques en technologies MESFETet HEMT : applications cinémométriques." Lille 1, 1996. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1996/50376-1996-133.pdf.
Full textAbstract:
Les applications des microondes dans le domaine grand public, sont actuellement en pleine expansion particulièrement dans les transports terrestres. L'électronique automobile est un grand espace qui offre un champ d'opportunités et un marché potentiel. La voiture du futur sera équipée d'un ensemble de capteurs intelligents, permettant une conduite plus automatisée et plus sure. Notre objectif consiste à développer une source microonde en bande k d'un capteur sans contact utilisant l'effet doppler pour accéder à la vitesse des automobiles. Cette source est composée d'un oscillateur et d'un amplificateur. Elle doit être de faible cout, fiable et facile à intégrer. Nous avons donc réalise une étude comparative entre la technologie hybride à base de mesfets, les technologies monolithiques à base de mesfets et à base de hemts. Une source hybride a 24 ghz a donc été réalisée utilisant un mesfet ec1840 de thomson composants microondes. Nous avons aussi entrepris la conception et la réalisation de 2 mmics (1 oscillateur et 1 amplificateur) au laboratoire central de l'iemn a base de mesfets utilisant un procède de gravure sèche. D'autre part, 2 mmics ont été réalisés avec la filière d02ah a base de hemts de la fonderie philips microwave limeil dans le cadre d'un projet multiutilisateurs. Chacune des sources réalisées a été testée et caractérisée sur banc de simulation routier. Ces mesures ont été très concluantes et permettent d'envisager l'intégration totale du capteur doppler en bande k. Ainsi, nous avons montré qu'il est possible de réaliser à moindre cout, en faisant appel à des technologies bien connues (mesfet et hemt), des systèmes intègres complexes en bande k.
28
Nie, Hanqing. "Analysis and Optimization of Parallel Gan Hemt for LLC Converters." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1627311347738337.
Full text
29
Embar, Ramanujam Srinidhi. "Intermodulation distortion modelling and measurement techniques for GaN HEMT characterization." Kassel Kassel Univ. Press, 2008. http://d-nb.info/992643643/04.
Full text
30
Taher, Mohammad Iktiham Bin. "New HEMT Type Sensors for In-situ Bio‐Geochemical Analysis." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0229.
Full textAbstract:
Une nouvelle classe de capteurs de gaz innovants basée sur des transistors à haute mobilité électronique (HEMT) AlGaN/GaN a été développée pour les applications géologiques. Elle est conçue dans le but d'étudier le transfert de masse des gaz (H2, CO2, CH4, O2, H2S, SO2 et He) entre le sous-sol et l'atmosphère sur de grandes étendues géographiques. Pour cela, elle intègre les caractéristiques clé suivantes : la miniaturisation, la robustesse, l'insensibilité aux environnements difficiles associées à un coût contenu. Les étapes technologiques comme la conception des capteurs, les technologies de micro-fabrication et l'optimisation des performances électriques des HEMT ont été continuellement étudiées et améliorées tout au long du travail. Ainsi, des densités de courant supérieures à 400 mA/mm, un courant de pincement = ~1×10-5 A et une transconductance = ~0,03 S/mm ont été atteints dans certaines conditions de polarisation. Les capteurs HEMT AlGaN/GaN traités avec différentes couches fonctionnelles (Pt, ITO et IZO) ont aussi été fabriqués et caractérisés pour différents gaz (H2, CO2, CH4 et He) en laboratoire et en environnement souterrain (Forage de 51 m) dans différentes conditions environnementales (température= 25 à 450°C, humidité= 0 à 100%). Grace à ces mesures, les enthalpies d'adsorption d'hydrogène ont été mesurées sur divers matériaux de détection tels que Pt, ITO et IZO et sont de -30.3 kJ mol^(-1), -32.5 kJ 〖mol〗^(-1) et -34 kJ 〖mol〗^(-1), respectivement. Ces valeurs indiquent que ITO et IZO sont complémentaires de Pt pour le développement d'un capteur d'hydrogène gazeux. Les HEMTs Pt/AlGaN/GaN ont été également été étudiés pour optimiser les performances des capteurs d'hydrogène dans l'air atmosphérique pur et dans le diazote afin de simuler les conditions souterraines, où la concentration d'O2 change avec la profondeur du sol. L'analyse thermodynamique montre que pour le Pt, l'affinité de H2 est environ 2000 fois supérieure à celle de l'O2. Cela rend le capteur adapté à la détection d'O2 dans l'air ou de divers mélanges d'O2 et de H2 en fonction des différentes profondeurs souterraines impliquées. Un lot de capteurs de gaz spécifique a été fabriqué avec des composants de capteur passivés (càd, non-actifs) comme référence pour la détection de gaz (capteur actif). Le capteur actif Pt/AlGaN/GaN fournit un changement de courant indiquant la présence de H2, tandis que le capteur non-actif n'indique aucun changement de courant en relation avec le gaz. Le capteur non-actif permet de suivre et d'éliminer les changements causés par les paramètres environnementaux externes comme la température. Cette thèse présente également de nouvelles techniques de mesure utilisant la polarisation par impulsions pour la détection des gaz souterrains avec les HEMT Pt-AlGaN/GaN. Au lieu d'imposer une polarisation d'entrée continue (toujours dans état ON) sur une longue période, le capteur est activé plusieurs fois successivement avec des impulsions sur de courtes périodes (état ON/OFF). Les capteurs ont ainsi montré une réponse rapide au gaz sous la forme d'une variation de courant significative jusqu'à des concentrations de 25 ppm. Toutes les expériences menées dans le cadre de cette étude ont démontré que les capteurs peuvent fonctionner dans divers scénarios de mesure susceptibles de se produire dans la situation réelle de détection de gaz en contexte géologique souterrainAn innovative gas sensor generation based on AlGaN/GaN High Electron Mobility Transistor (HEMT) has been developed for complex geological environments. It is designed to study the mass transfer of gases (H2, CO2, CH4, O2, H2S, SO2, and He) from the underground to the Earth's atmosphere. It incorporates the key features for subsurface gas sensor development such as miniaturization, robustness, insensitivity to harsh environments, and low cost.Technological steps, design of the sensor layouts, micro-fabrication techniques, and optimization of the electrical performance of the HEMTs have been continuously investigated and improved. Current densities above 400 mA/mm and pinch-off current= (~1×10-5 A), and transconductance (gm)= ~0.03 S/mm have been achieved for certain bias conditions. At the same time, the processed AlGaN/GaN HEMT sensors with different functional layers (Pt, ITO, and IZO) are fabricated and characterized for different gases (H2, CO2, CH4, and He) in the laboratory, and real subsurface conditions (Borehole: 51 m) under different environmental conditions (temperature= 25 to 450°C, humidity= 0 to 100%). The measured adsorption enthalpies of hydrogen onto various sensing materials like Pt, ITO, and IZO are calculated -30.3 kJ mol^(-1), -32.5 kJ 〖mol〗^(-1), and -34 kJ 〖mol〗^(-1), respectively, indicating that ITO and IZO are complementary to Pt for the development of a hydrogen gas sensor.Pt/AlGaN/GaN-based HEMT devices have been studied to evaluate the performance of hydrogen sensors in pure atmospheric air and a fully N2-based atmosphere to simulate subsurface conditions where the O2 concentration changes over the depth of the soil. From the thermodynamic analysis, the affinity of hydrogen for Pt was found nearly 2000 times greater than the affinity of oxygen for platinum. This makes the sensor suitable for detecting hydrogen in the air or various mixtures of O2 and H2 at different underground depths imply.A dedicated gas sensor batch has been fabricated with passivated (i.e., non-active) sensor components as a reference for gas detection (active sensor). The active sensor Pt/AlGaN/GaN provided a change in current indicating a response to the hydrogen exposure, while the non-active (Passivated-Pt/AlGaN/GaN) provides no changes in current. But non-active sensor (reference) tracks and eliminates the changes caused by external environmental parameters.This thesis also presents new measurement techniques using pulse polarization for subsurface gas detection with a Pt-AlGaN/GaN HEMT sensor. Instead of imposing a continuous input bias (which always maintains the ON state) over a long period of the experiment, the sensor is activated several times with pulsed polarization for a short period of time (ON/OFF state). The sensors showed a sufficiently fast response to the target gas by changing the drain current in pulsed bias mode with a linear increase in output current even at very low concentrations such as 25 ppm. All the experiments conducted in the study demonstrated that the sensors could work in various measurement scenarios that may occur in the real situation of subsurface gas detection
31
Manzoli, José Eduardo. "Efeito de campo em heteroestruturas semicondutoras de dispositivos eletrônicos quânticos." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-19082015-112652/.
Full textAbstract:
Os efeitos do campo elétrico, que surgem pela aplicação de uma voltagem no contato Schottky, na estrutura eletrônica de heteroestruturas semicondutoras utilizadas nos recentes transistores de efeito de campo (FET) e numa super-rede finita são simulados numericamente. Estas heteroestruturas apresentam poços quânticos bidimensionais e camadas que podem estar tensionadas pela diferença entre os parâmetros de rede cristalinos. Através de um procedimento numérico auto-consistente várias grandezas físicas são estudadas, os auto-estados e as densidades eletrônicas nas sub-bandas são calculadas. A variação destas grandezas é associada à capacitância e à transcondutância intrínseca, em função da voltagem no gate. Os resultados da simulação são comparados aos dados experimentais. Este procedimento possibilita a compreensão dos fenômenos quânticos envolvidos com a previsão de certas características de dispositivos sem a necessidade prévia de sua produção e testesEletric field effects on the electronic characteristics of semiconductor heterostructures used in recent field effect transistors (FETs) and in a finite superlattice are numerically simulated. This field is due to a voltage bias applied on a Schottky contact. These heterostructures have two-dimensional quantum wells and layers wich can be stressed due to different lattice parameters of the materials involved. Through a numerical self-consistent procedure, many physical quantities are studied, such as the eigen-states and the electronic densities at the sub-bands. The changes in such quantities are associated to the capacitance and to the intrinsic transconductance as a function of the gate voltage. The results are compared to experimental data. This procedure allows the comprehension of the quantum phenomena involved and the prediction of device characteristics, without the need to fabricate and test it
32
Trovarello, Simone. "Selezione automatica di rettificatori a RF SIMO mediante autopolarizzazione di HEMT." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21835/.
Full textAbstract:
Nella tesi viene proposto un sistema innovativo di Energy Harvesting per radiofrequenze a 2.45 GHz. Si tratta di un sistema single-input multiple-output ad ampissimo range dinamico di potenza in ingresso che sfrutta il fenomeno di autopolarizzazione di dispositivi non lineari come gli HEMT per selezionare autonomamente, e senza alcun controllo esterno, il ramo di rettificazione più adeguato al fine di ottenere la massima RF-to-DC conversion efficiency possibile. Inoltre il sistema garantisce il massimo isolamento fra i rami che compongono il circuito sfruttando l'ottimizzazione dei Large Signal S-Parameters dei singoli stadi del sistema.
33
Adeyemi, Oluwafemi Ibukunoluwa. "The design of GaAs HEMT and HBT Bessel-type transimpedance amplifiers." Thesis, Texas A&M University, 2006. http://hdl.handle.net/1969.1/4663.
Full textAbstract:
The need of the everyday user to transfer large amounts of data is driving the need for larger data transfer capacity. Optical communication networks can satisfy this need. To be economically viable, optical transceivers must be integrated onto chips at low cost, using relatively cheap semiconductor processes. The optical preamplifier (transimpedance amplifier) receives optical information and converts it to a useful electrical form. It must operate at high speed, contribute little distortion to the input signal, and add little electrical noise to the incoming signal. This thesis investigates the design techniques in the literature, and proposes new architectures. Two high performance preamplifiers are designed, one using GaAs HEMTs, and the other using GaAs HBTs, each with different circuit techniques. The HEMT preamplifier has a transimpedance gain of 1.4 kâ¦, the highest in the literature for 10 Gb/s operation, along with a low input referred noise current of about 15 pA/Hz1/2 at a bandwidth of 6.3 GHz. The HBT preamplifier also has a transimpedance gain of 1.5 kâ¦, with a low input referred noise current of about 7 pA/Hz1/2. Both have clear, open eye-diagrams with a 10 Gb/s bit stream input, and are suitable for integration on a chip. The HEMT preamplifier was implemented as a common-gate, common-source amplifier cascade with a darlington output driver for a 50 ⦠load. The HBT preamplifier was implemented as common-emitter darlington amplifier with shunt peaking, and a simple emitter degenerated output driver for a 50 ⦠load. Both implementations exceeded the bandwidth, transimpedance gain and noise performance typically expected of the transistor technologies used. It is shown that the transimpedance limit can be circumvented by the use of novel architectures and shunt peaking.
34
Meiners, Joseph R. "Simulation and design of a submicron gate-length AIHaN/GaN HEMT." Cincinnati, Ohio University of Cincinnati, 2007. http://www.ohiolink.edu/etd/view.cgi?ucin1177520581.
Full text
35
Abbade, Marcelo Luís Francisco. "Caracterização óptica de uma estrutura tipo HEMT de GaAs/InGaAs/AlGaAs." [s.n.], 1996. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277776.
Full textAbstract:
Orientador: Fernando IikawaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Watagin
Made available in DSpace on 2018-07-23T03:23:12Z (GMT). No. of bitstreams: 1 Abbade_MarceloLuisFrancisco_M.pdf: 953476 bytes, checksum: edf6ffafdcada1366617108564a3f2e8 (MD5) Previous issue date: 1997
Resumo: Realizamos um estudo das propriedades ópticas de uma estrutura tipo HEMT de um poço quântico de GaAs/InxGa1-xAs/AlyGa1-yAs com dopagem modulada. Neste estudo, utilizamos técnicas de medidas de espectroscopia de fotoluminescência, fotoluminescência de excitação, magnetoluminescência e de magnetotransporte. As amostras são altamente dopadas resultando em alta densidade bidimensional de elétrons. Os dados obtidos com a técnica de Shubnikov-de-Haas apresentam oscilações que são características de um sistema de gás bidimensional. O ponto principal discutido neste trabalho é sobre a observação experimental de transições indiretas nos espectros de fotoluminescência. Estas transições envolvem os estados eletrônicos do poço de potencial criado na barreira de AIGaAs, devido a dopagem planar, e o estado fundamental do buraco pesado do poço de InGaAs. Esta observação é sustentada pelos resultados do cálculo auto-consistente obtido das soluções das equações acopladas de Schrodinger e de Poisson
Abstract: We report a study on optical properties of a GaAs/ InGaAs/ AIGaAs modulation doped quantum well HEMT structure. In this study we performed photoluminescence, photoluminescence excitation, magnetoluminescence and magnetotransport measurements. The analyzed samples were highly doped in order to provide a high bidimensional electron gas density. In fact, Shubnikov-de-Haas data exhibited oscillations that are typical of a bidimensional electron gas system. The main point of this work is the discussion about the experimental observation of indirect transitions in the photoluminescence spectra. Such transitions involve electronic states in the AIGaAs barrier well, created by the planar doping, and the ground heavy hole state in the InGaAs quantum well. This observation is supported by the self-consistent calculation results of Poisson and Schfodinger coupled equations
Mestrado
Física
Mestre em Física
36
MEINERS, JOSEPH R. "SIMULATION AND DESIGN OF A SUBMICRON GATE-LENGTH AIGaN/GaN HEMT." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1177520581.
Full text
37
Langley, Derrick. "AlGaN/GaN HEMT Topology Investigation Using Measured Data and Device Modeling." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1177728294.
Full text
38
Coulianos, Natalie N. G. "Regulation of hemT expression in Rhodobacter sphaeroides wild type strain 2.4.9." Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1522070574933425.
Full text
39
Chiron, Lionel. "Couplage optimal d'une antenne IRM supraconductrice avec un transistor HEMT refroidi." Paris 11, 2003. http://www.theses.fr/2003PA112246.
Full textAbstract:
En IRM la sensibilité du détecteur joue un rôle déterminant sur la résolution spatiale et temporelle accessible. Le circuit inductif du détecteur doit avoir un facteur de qualité (Q) élevé comme en IRM bas champ ou en microscopie RMN sur de petites régions anatomiques. L'adaptation du détecteur à un préamplificateur est alors difficile à réaliser sur la bande de fréquence nécessaire à la transmission du signal d'imagerie. Le chapitre 1 traite du couplage antenne-préamplificateur dans la littérature. Il existe une limite théorique en bande passante, dite limite de Fano. Il est montré que pour une dégradation constante du rapport signal-surbruit (RSB), la largeur de bande atteignable est inversement proportionnelle à la température de bruit Tn du préamplificateur. Le chapitre II est consacré à la recherche et à la caractérisation d'un amplificateur refroidi dépassant les limites de l'état de l'art en électronique RMN faible bruit. Les HEMTs sont les meilleurs candidats aux fréquences IRM mais leurs caractéristiques ne sont pas bien connues à ces fréquences et à basse température. Une méthode de caractérisation a été appliquée en combinant la mesure de paramètres S et le modèle de transistor bruyant de Pospieszalski. La caractérisation a été menée à 293 K et à 100 K. Le chapitre III traite de l'optimisation du couplage antenne-préamplificateur. L'étude est détaillée dans le cas d'un couplage inductif du second ordre qui offre le meilleur compromis efficacité/simplicité. Dans le chapitre IV les résultats précédents sont appliqués à la conception d'un prototype de préamplification intégré à un détecteur supraconducteur dédié à la microscopie localisée in-vivo à 1,5TIn MRI the sensitivity of the detector plays a determining part on the spatial and temporal resolution available. The detector inductive circuit must have a high quality factor (Q) as in low field MRI or in NMR microscopy on small anatomical areas. The adaptation of the detector to a preamplifier is then difficult to realize on the frequency band necessary to the transmission of the signal. The chapter 1 deals with antenna-preamplifier coupling in the literature. There is a theoretical limit in band-width, known as limit of Fano is shown that for a constant degradation of the signal to noise ratio (SNR) the bandwidth achievable is inversely proportional to the noise temperature Tn noise of the preamplifier. Chapter II is devoted to the search and the characterization of a cooled amplifier exceeding the limits of l'état de l'art in weak noise NMR electronics. HEMTs are the best candidates at MRI frequencies but their characteristics are not well-known at these frequencies and low temperature. A method of characterization was applied by combining measurement of parameters S and the model of Pospieszalski nois transistor. The characterization was carried out to 293 K and 100 K. The chapter III deals with the optimisation of antenna-preamplifier coupling. The study is detailed in the case of an inductive coupling of the second order which offers the best tradeoff efficiency/simplicity. In chapter IV the preceding results are applied to the prototype preamplification design of a superconductive detector dedicated to microscopy located in-vivo with 1,5T
40
Samnouni, Mohammed. "Fabrication et caractérisation du HEMT InP pour amplification faible bruit THz." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I103.
Full textAbstract:
Les avancées des technologies III-V permettent aujourd’hui de concevoir des composants électroniques fonctionnant en gammes millimétrique et submillimétrique (fréquences Terahertz) pour répondre aux besoins émergeants du marché des télécommunications et de l’électronique à destination de différents secteurs industriels. L’électronique THz trouve des débouchées importantes dans les applications d’imagerie, entre autres pour la sécurité et les communications sans fils ultra haut débit (5G plus).La technologie des transistors HEMT InP a connu ces dernières années un progrès remarquable dans la réalisation des circuits intégrés à très hautes fréquences (fréquence de fonctionnement à 1 THz) et de faible bruit. Peu d’acteurs mondiaux de la microélectronique (aucun en France) ont établi des performances atteignant ces fréquences THz. Nous proposons de développer une technologie répondant à cette demande.Dans ces travaux de thèse, nous proposons de développer des HEMT InAlAs /InGaAs/InAs sur substrat d’InP de fréquence de coupure THz pour amplification faible bruit dans les systèmes de réception-détection THz. Nous avons pour cela optimisé la structure semiconductrice utilisée afin d’obtenir un meilleur compromis mobilité/charges électroniques. Nous avons également apporté des modifications géométriques (longueur de grille, taille du recess et espacements des électrodes du transistor) qui ont permis d’augmenter considérablement les fréquences de fonctionnement du transistor. Nous avons réalisé des mesures de paramètres S jusque 750 GHz et en bruit jusque 110 GHz, afin de valider les optimisations technologiques apportées à la structure HEMTProgress of III-V technologies are now making it possible to design electronic components operating in the millimeter and sub-millimeter wave range (THz) are facing the needs of the telecommunications and electronics market for various industrial sectors. The technology of InP High Electron Mobility Transistor (HEMT) allowed in recent years a remarkable progress in the realization of integrated circuits at very high frequencies (operating frequency at 1 THz) and low noise. Few world players in microelectronics (none in France) have established performances reaching these THz frequencies. We propose to develop a technology that meets this demand.We propose to develop InAlAs /InGaAs/InAs HEMT with THz cutoff frequency and low noise, mainly for reception-detection THz electronic system. The work will therefore focus on the determination of an optimal epitaxial structure using InAlAs/InGaAs/InAs materials by performing Hall effect measurements of several heterostructures, in order to determine the layer offering a better mobility / electronic charges tradeoff. The modifications of the transistor geometry (gate length, recess size and the spacings of the electrodes of the transistor) made it possible to considerably increase the operating frequency of the transistor. We achieved the characterizations of S-parameters up to 750 GHz and noise up to 110 GHz, in order to validate the technological optimizations
41
Eliason, Garth W. "HEMT-compatible laser diodes." Thesis, 1994. http://hdl.handle.net/1957/35668.
Full text
42
Liu, Cheng-Chih, and 劉政志. "The Fabrication and Analysis of High Frequency AlGaN/GaN HEMT and AlInN/GaN HEMT." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/64732834284178885341.
Full textAbstract:
碩士國立清華大學
電子工程研究所
101
In this thesis, we compare the DC and RF characteristics of AlGaN/GaN and AlInN/GaN HEMTs and their equivalent small signal signal circuit model are constructed and compared. For the DC characteristics the saturated current density(Idss) and the transconductance(Gm) of the AlInN/GaN HEMT is 1271mA/mm and 231mS/mm respectively which are higher than the AlGaN/GaN’s value 900mA/mm and 187mS/mm because of the higher 2DEG concentration in AlInN/GaN. But the leakage current of the AlInN/GaN HEMT is also higher than that of AlGaN/GaN HEMT. For high frequency characteristics, the AlInN/GaN HEMT shows an ft=82GHz and an fmax=70GHz, which is also higher than the AlGaN/GaN’s numbers because of the higher transconductance of AlInN/GaN HEMT. But for RF power characteristics the AlInN/GaN HEMT is poor than AlGaN/GaN HEMT due to the higher leakage current of AlInN/GaN HEMT. Finally we extract small signal parameters, contstruct equivalent circuit models, and compare their intrinsic values. From the extracted values, It is found that the intrinsic gm of AlInN/GaN HEMT is higher than the AlGaN/GaN which is also attributed to the higher carrier density on the AlInN/GaN wafer.
43
Wang, Chieh-An, and 王婕安. "Electro-Thermal Simulation and Heat Dissipation Analysis of Packaged GaN Power-HEMT Devices." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/80245632143150963673.
Full textAbstract:
碩士國立交通大學
機械工程系所
103
AlGaN/GaN high electron mobility transistors（HEMTs）are one of the prospective candidates for high switching frequency power electronics applications thanks to its wide band gap（3.4eV）, high breakdown voltage, large critical electric field, high carrier mobility, and the inherent high speed characteristics. With the high power densities that AlGaN/GaN HEMTs are capable of reaching, heat dissipation is a crucial issue. This research presents an in depth thermal study of packaged GaN on Si power devices. The device is attached in a V-groove copper base, to enhance Si substrate thermal dissipation. The effects of structure design and fabrication processes on the device performance were studied. To improve the reliability and the performance of GaN power-HEMT devices, thermal management is one of the most critical aspects. Micro-Raman spectroscopy and Infrared（IR）thermography were used to identify temperature profiles and the hot spots of the devices. For the purpose of more precise temperature measurements, temperature vs. Raman shift curve fitting of experimental data of our device is illustrated. The measurements of longitudinal temperature have been acquired, so that the position of the hottest layer（2DEG）is realized. Then, Raman area temperature map measured over the lateral hottest layer depicted in this study. The comparison between Raman/IR experiment results and finite-element electro and thermal simulation has been shown.
44
Chang, Ying-Tang, and 張英堂. "HEMT Frequency Multiplier and Filter Design." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/14201450872789658637.
Full textAbstract:
碩士國立臺灣大學
電信工程學研究所
89
This thesis describes the HEMT frequency multiplier design and filter design at millimeter-wave frequency. HEMT frequency multipliers include a monolithic 42-to-84 GHz doubler, a monolithic 14-to-42 GHz tripler, a monolithic 31-to-94 GHz balanced tripler, and a monolithic 19-to-76 GHz balanced quadrupler. Filters are designed for a local multi-point distributed service (LMDS) system. The 27.35~28.35 GHz filter is used at receiver-end and the 31~31.3 GHz filter is used at transmitter-end. For the millimeter-wave frequency band, monolithic microwave integrated circuit frequency multipliers are designed with microstrip line configuration. The MMIC frequency doubler and triplers are fabricated on 4-mil-thick GaAs substrates using 0.1-μm InGaAs/AlGaAs/GaAs PHEMT technology provided by commercially available foundry service, which is accessed through the Chip Implementation Center of National Science Council of Taiwan. The MMIC balanced frequency quadrupler is fabricated on 4-mil-thick GaAs substrates using 0.15-μm InGaAs/AlGaAs/GaAs PHEMT technology. In order to prove the balanced configuration that can suppress the second harmonic signal by phase cancellation nature, a hybrid circuit was implemented on FR4 substrates using PHEMT devices, respectively. The filters for a LMDS system are manufactured on Al2O3 substrates with microstrip coupled line configuration. The box resonance are observed by the measurement of both receiver-end and transmitter-end filter with different box height. Hence, housing effect should be considered in the beginning of filter design. Besides, the simulated results of both Rx and Tx filters are close to measurement.
45
李奕辰. "Novel Light Emitting AlGaN/GaN HEMT." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/7efx9a.
Full text
46
Tan, Kuang-Hsiung, and 談光雄. "Fabrication of enhancement-mode psedomorphic HEMT." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/18357416173665693874.
Full textAbstract:
碩士國防大學中正理工學院
電子工程研究所
95
Recently, the wireless area network (WLAN) becomes the public study topic of communication; especially the protocal 802.11a of wireless area network will be developed. There is high frequency, high power and linear related requirements in this communication protocol, but traditional metal-oxide-semiconductor field emitting transistor (MOSFET) by deep sub-micron technology can't reach those requirements, and hetro-junction field emitting transistor technology is still limited by negative-biased on gate in development of power amplifier. These is the results of that the large area of the circuits and low down the commercial competition. The main target of the project is fabricating enhancement-mode pHEMT. Due to the interfacial oxide layer formation by adding the rare earth metal laye in the bottom of gate metal, which also results in a gate leakage current and turn on voltage performance improvement. Used to design a single voltage supply, a high gain, a high linearity, and a low power consumption active device for power amplifier and low noise amplifier with enhancement mode mode pHEMT.
47
Lai, Sin-Hong, and 賴信宏. "Characteristic Analysis of SiN Gate Dielectric Layer MIS-HEMT Device and Investigation of MOS-HEMT Flash Memory." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/24505796689449958478.
Full textAbstract:
碩士龍華科技大學
電子工程系碩士班
103
Gallium nitride compared with other materials has the advantage with wide bandgap, high breakdown electric field and high electron saturation velocity, etc. Gallium nitride is a good material for high power, high frequency and optics applications. Metal semiconductor junction high electron mobility transistor can't effectively suppress gate leakage current in high bias due to its limited barrier height properties. Therefore, we adopt metal oxide semiconductor structure high electron mobility transistors to reduce gate leakage and surface states density. In this thesis, we proposed in-situ silicon nitride as gate dielectric layer, and changed deposition conditions of silicon nitride to investigate the variety of deposition conditions of silicon nitride thin film for effect of device performance. Conventionally AlGaN/GaN HEMT device which operating mode is the depletion mode. Depletion mode of device for circuit design has high complexity and fail-safe problem in high power operation. For this reason, there are some methods to make device in enhancement mode. In this thesis, we proposed charge trapping method to confine electrons in the charge storage layer, to change space charge of device, so that threshold voltage toward positive voltage shift.
48
Liang, Hsien-Chang, and 梁獻章. "The Fabrication of High Power HEMT Device." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/40745393547051000391.
Full textAbstract:
碩士國立交通大學
電子物理系
86
In this study, we have developed the processing techniques for GaAs Power HEMT. The process starts with the three basic fabrication steps used in general FET processing. These include meas etch, obmic contact formation and gate formation. We have also successfully developed two specific process steps: electropalting and airbridge setting. In the process of electroplating, the thickness of Au can be controlled in the ranges from 2 μm and 12 μm maximum, and the boundary between the electroplated and unelectroplated areas is very sharp. From the airbridge process, the maximum length of airbridge can be 30 μm, and the distance between airbridge and wafer is 2μm. Finally, a 1.8 μm gate length GaAs power HEMT was successfully fabricated, which exhibited a output power of 1OdBm at 2.4 GHz. The maximum transconductance and saturated current of the device were 115mS/mm and 150mA/mm, respective. The HEMT demonstrated a current gain cut-off frequency, fT, of 8.2 GHz, and power gain cut-off frequency, fmax,of 16 GHz.
49
Huang, Wei-Hsun, and 黃瑋珣. "GaN HEMT Modeling and Passive Mixer Design." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/81543692717494340013.
Full textAbstract:
碩士國立清華大學
電子工程研究所
100
本論文可分成兩部分討論，第一部分是氮化鎵高電子移導率電晶體模型的建立，包含小訊號及大訊號模型，第二部分提出了兩種不同的被動混頻器架構，包含基頻混頻器與次諧波混頻器。 在第一部分首先我們利用cold-FET量測來萃取出外部寄生的電阻和電感值，再利用Y參數將外部寄生的參數扣除掉之後，可以計算出內部等校電路的元件值。在本論文中採用Angelov的模型做為我們的電流模型，此模型中的各個參數可利用擬合的方式獲取，另外將內部元件值隨電壓變化的關係也用方程式擬合，最後在ADS中建立出完整的電晶體等效模型，並比較量測與模擬的直流特性與S參數。 在第5章中，我們提出一種寬頻高線性度的被動混頻器，此混頻器是利用第2和3章建立出的電晶體模型來設計，我們所採用的元件大小是2×100 μm，IF頻率固定在1 GHz，可得到頻率操作在11-18 GHz，轉換損耗最小為7.9 dB的被動混頻器，此混頻器的P1dB和IIP3為13和22 dBm。 在第六章中，我們提出另一種被動混頻器架構，此混頻器是利用穩懋半導體提供的0.15 μm pHEMT 元件設計並製作，此混頻器操作在11-21 GHz，擁有轉換損耗8.8-11.8 dB，其P1dB和IIP3為3和6 dBm。
50
"Analysis of Heat Dissipation in AlGaN/GaN HEMT with GaN Micropits at GaN-SiC Interface." Master's thesis, 2016. http://hdl.handle.net/2286/R.I.41224.
Full textAbstract:
abstract: Gallium Nitride (GaN) based microelectronics technology is a fast growing and most exciting semiconductor technology in the fields of high power and high frequency electronics. Excellent electrical properties of GaN such as high carrier concentration and high carrier motility makes GaN based high electron mobility transistors (HEMTs) a preferred choice for RF applications. However, a very high temperature in the active region of the GaN HEMT leads to a significant degradation of the device performance by effecting carrier mobility and concentration. Thus, thermal management in GaN HEMT in an effective manner is key to this technology to reach its full potential.
In this thesis, an electro-thermal model of an AlGaN/GaN HEMT on a SiC substrate is simulated using Silvaco (Atlas) TCAD tools. Output characteristics, current density and heat flow at the GaN-SiC interface are key areas of analysis in this work. The electrical characteristics show a sharp drop in drain currents for higher drain voltages. Temperature profile across the device is observed. At the interface of GaN-SiC, there is a sharp drop in temperature indicating a thermal resistance at this interface. Adding to the existing heat in the device, this difference heat is reflected back into the device, further increasing the temperatures in the active region. Structural changes such as GaN micropits, were introduced at the GaN-SiC interface along the length of the device, to make the heat flow smooth rather than discontinuous. With changing dimensions of these micropits, various combinations were tried to reduce the temperature and enhance the device performance. These GaN micropits gave effective results by reducing heat in active region, by spreading out the heat on to the sides of the device rather than just concentrating right below the hot spot. It also helped by allowing a smooth flow of heat at the GaN-SiC interface. There was an increased peak current density in the active region of the device contributing to improved electrical characteristics. In the end, importance of thermal management in these high temperature devices is discussed along with future prospects and a conclusion of this thesis.Dissertation/Thesis
Masters Thesis Electrical Engineering 2016