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Dissertations / Theses on the topic 'Diodes, Semiconductor'

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Published: 4 June 2021
Last updated: 29 July 2024

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1

Ma, Cliff Liewei. "Modeling of bipolar power semiconductor devices /." Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/6046.

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2

Modi, Nihar Triplett Gregory Edward. "Thermal management in GaAs/AlGaAs laser diode structures." Diss., Columbia, Mo. : University of Missouri--Columbia, 2007. http://hdl.handle.net/10355/6262.

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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 16, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis supervisor: Dr. Gregory Triplett. Includes bibliographical references.
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3

Meyers, Mark. "Laser diodes incorporating diffractive features /." Online version of thesis, 1990. http://hdl.handle.net/1850/11233.

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4

Belhadj-Yahya, Chedly. "Evaluation of the quantum well tunneling diode and the quantum electron-wave interference diode as high speed devices." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/15348.

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5

Los, Andrei. "Influence of carrier freeze-out on SiC Schottky junction admittance." Diss., Mississippi State : Mississippi State University, 2001. http://library.msstate.edu/etd/show.asp?etd=etd-03272001-120540.

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6

Chan, Alan Chin Luen. "Fabrication and measurements on metal-semiconductor diodes." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63966.

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7

Leong, Hank W. H. "Investigation of dopant profiles from capacitance-voltage measurements on Schottky diodes." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29997.

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Measurement of the differential capacitance (C) of a Schottky diode as a function of voltage (V) is widely used to probe dopant profiles in semiconductors. However, the theory of the dopant profiling method is based on an approximation, and does not work well when the dopant concentration changes rapidly with distance. The region beyond the maximum of an implanted Gaussian profile is of particular interest in connection with ingot qualification tests for GaAs, and it is just there that the problem is the most serious. In this thesis, an investigation was made by numerical simulation on problems associated with the profiling method. Programs were written to calculate the differential capacitance-voltage relation for GaAs Schottky diodes with and without deep energy levels, and with a specified dopant distribution. The programs predict what the approximation method would indicate for the dopant profiles according to a set of canonical equations used in the profiling method. The predicted and the specified dopant profiles were then compared. Mainly ion-implanted dopant profiles in semiconductors were studied although doped epitaxial layers were also considered. For ion-implanted GaAs, the predicted dopant profiles were found to be about 10% lower near the peak region than the true dopant profiles, and the predicted profiles were confirmed to be too high in the tail region. For doped epitaxial layers, the predicted profile was found, in some cases, to give good estimates for the dopant concentrations on the high and low sides of the true step profile, but in some others, the predicted profiles were found to be totally misleading. For GaAs with deep levels, a method of calculating the differential capacitance was developed to take into account the fact that the deep levels do not respond to the 1 MHz a.c. signal normally used in the C(V) measurements. It is believed to simulate the experimental C(V) measurements more realistically. The tail sections of the predicted profiles were found to increase with the concentration of background shallow donor atoms in the deep-level-free semiconductor before ion-implantation, and with the number of impurity atoms which are channelled or diffused to the region during or after ion-implantation. This implies that although the profiling method is erroneous in the tail section, it can nevertheless be used on a comparative basis to indicate the level of background shallow dopant concentration, and the degree of channelling or diffusion. The effects of the substrate parameters in liquid encapsulated Czochralski (LEC) GaAs, which include the concentrations of EL2, net shallow acceptors, and sometimes Cr, have been investigated on the predicted dopant profiles for ion-implanted samples. Increases in Cr and net shallow acceptor concentrations were found to increase the steepness of the predicted dopant profile, while an increase in EL2 concentration has little effect. A method of estimating dopant activation efficiency in GaAs has been proposed. This method uses the author's second program to avoid underestimations of the activation efficiency in GaAs caused by the peak lowering in the predicted dopant profiles. The concept of Debye length in semi-insulating LEC GaAs was also discussed. The Debye length given by the standard formula for semiconductors with shallow donors and acceptors can become inapplicable when deep levels are present.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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8

Santhanam, Parthiban. "Thermo-electrically pumped semiconductor light emitting diodes." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87935.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 217-227).
Thermo-electric heat exchange in semiconductor light emitting diodes (LEDs) allows these devices to emit optical power in excess of the electrical power used to drive them, with the remaining power drawn from ambient heat. In the language of semiclassical electron transport, the electrons and holes within the device absorb lattice phonons as they diffuse from their respective contacts into the LED's active region. There they undergo bimolecular radiative recombination and release energy in the form of photons. In essence the LED is acting as a thermodynamic heat pump operating between the cold reservoir of the lattice and the hot reservoir of the outgoing photon field. In this thesis we report the first known experimental evidence of an LED behaving as a heat pump. Heat pumping behavior is observed in mid-infrared LEDs at sub-thermal forward bias voltages, where electrical-to-optical power conversion at arbitrarily high efficiency is possible in the limit of low optical output power. In this regime, the basic thermal physics of an LED differs from that seen at conventional higher voltage operating points. We construct a theoretical model for entropy transport in an LED heat pump and examine its consequences both theoretically and experimentally. We use these results to propose a new design for an LED capable of very high efficiency power conversion at power densities closer to the limit imposed by the Second Law of Thermodynamics. We then explore the potential application of these thermo-photonic heat pumps as extremely efficient sources for low-power communication and high-temperature absorption spectroscopy.
by Parthiban Santhanam.
Ph. D.
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9

Phillips, Amyas Edward Wykes. "Passive wavelength athermalisation of semiconductor laser diodes." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615225.

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10

Lee, Junho. "Semiconductor diode laser with saturable absorber (S-laser)." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004277.

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11

Parker, Danny Loren. "Versatile automated semiconductor testing and characterization." Master's thesis, Mississippi State : Mississippi State University, 2001. http://library.msstate.edu/etd/show.asp?etd=etd-11122001-163337.

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12

Morton, Paul A. "The dynamics of directly modulated semiconductor laser diodes." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382591.

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13

Cappuccio, Joseph C. "Semiconductor laser diodes and the design of a D.C. powered laser diode drive unit/." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23114.

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This thesis addresses the design, development and operational analysis of a D.C. powered semiconductor laser diode drive unit. A laser diode requires an extremely stable power supply since a picosecond spike of current or power supply switching transient could result in permanent damage. The design offers stability and various features for operational protection of the laser diode. The ability to intensity modulate (analog) and pulse modulate (digital) the laser diode output for data transmission was a major design consideration. Laser optical power is controlled via a closed loop system using a monitor photodiode. Laser diode temperature stabilization is accomplished with the use of a thermoelectric cooler. Laboratory and remote applications were considered in the design of this unit. (rh)
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14

Othaman, Zulkafli Bin. "Hydrostatic pressure studies of semiconductor heterostructures and Schottky diodes." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295450.

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15

Li, Zonglin, and 李宗林. "Reliability study of InGaN/GaN light-emitting diode." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43224155.

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16

Li, Zonglin. "Reliability study of InGaN/GaN light-emitting diode." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43224155.

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17

Bizetto, César Augusto. "Caracterização das propriedades dosimétricas de diodos de silício empregados em radioterapia com feixe de fótons." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-08082013-164400/.

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No presente trabalho foi estudada a resposta de diodos epitaxiais (EPI) e fusão zonal (FZ) como dosímetros on-line em tratamentos radioterápicos com feixe de fótons na faixa de megavoltagem (diodo tipo EPI)e ortovoltagem (diodos tipo EPI e FZ). Para serem usados como dosímetros os diodos foram encapsulados em sondas de polimetilmetacrilato preto (PMMA). Para as medidas da fotocorrente os dispositivos foram conectados a um eletrômetro Keithley® 6517B no modo fotovoltaico. As irradiações foram feitas com feixes de fótons de 6 e 18 MV (acelerador Siemens Primus®),6 e 15 MV (acelerador Novalis TX®) e 10, 25, 30 e 50 kV de um equipamento de Radiação X Pantak/Seifert. Nas medidas com o acelerador Siemens Primus® os diodos foram posicionados entre placas de PMMA a uma profundidade de 10,0 cm e com o acelerador Novalis TX® mantidos entre placas de água sólida a uma profundidade de 5cm. Em ambos os casos, os diodos foram centralizados em campos de radiação de 10 × 10 cm2, com distância fonte superfície (DFS) mantida fixa em 100 cm. Para as medidas com os feixes de fótons deortovoltagem os diodos foram posicionados a 50 cm do tubo em um campo de radiação circular de 8 cm de diâmetro. A linearidade com a taxa de dose foi avaliada para as energias de 6 e 15MV do acelerador Novalis TX® variando-se a taxa de dose de 100 a 600 unidades monitoras por minuto e para o feixe de 50 kV variando-se a corrente do tubo de 2 a 20 mA. Todos os dispositivos apresentaram respostas lineares com a taxa de dose e dentro das incertezas, independência da carga com a mesma. Os sinais de corrente mostraram boa repetibilidade, caracterizada por coeficientes de variação em corrente (CV) inferiores a 1,14%(megavoltagem) e 0,15%(ortovoltagem) e em carga menores que 1,84% (megavoltagem) e 1,67% (ortovoltagem). Foram obtidas curvas dose-resposta lineares com coeficientes de correlação linear melhores que 0,9999 para todos os diodos.
In the current work it was studied the performance of epitaxial (EPI) and float zone (FZ) silicon diodes as on-line dosimeters for megavoltage (EPI diode) and orthovoltage (EPI and FZ diode) photon beam radiotherapy. In order to be used as dosimeters the diodes were enclosed in black polymethylmethacrylate (PMMA) probes. The devices were then connected, on photovoltaic mode, to an electrometer Keithley® 6517B to allow measurements of the photocurrent. The irradiations were performed with 6 and 18 MV photon beams (Siemens Primus® linear accelerator), 6 and 15 MV (Novalis TX®) and 10, 25, 30 and 50 kV of a Pantak / Seifert X ray radiation device. During the measurements with the Siemens Primus® the diodes were held between PMMA plates placed at 10.0 cm depth. When using Novalis TX® the devices were held between solid water plates placed at 50 cm depth. In both casesthe diodes were centered in a radiation field of 10 x 10 cm2, with the source-to-surface distance (SSD) kept at 100 cm. In measurements with orthovoltage photon beams the diodes were placed 50.0 cm from the tube in a radiation field of 8 cm diameter. The dose-rate dependency was studied for 6 and 15 MV (varying the dose-rate from 100 to 600 monitor units per minute) and for the 50 kV beam by varying the current tube from 2 to 20 mA. All devices showed linear response with dose rate and, within uncertainties the charge collected is independent of dose rate. The current signals induced showed good instantaneous repeatability of the diodes, characterized by coefficients of variation of current (CV) smaller than 1.14% (megavoltage beams) and 0.15% for orthovoltage beams and coefficients of variation of charge (CV) smaller than 1.84% (megavoltage beams) and 1.67% (orthovoltage beams). The doseresponse curves were quite linear with linear correlation coefficients better than 0.9999 for all diodes.
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18

Fritz, Mark A. Cassidy Daniel Thomas. "Die bonding of diode lasers /." *McMaster only, 2004.

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19

Laino, Valerio. "Performance analysis of edge emitting lasers in the mid infra-red and visible spectrum." Konstanz Hartung-Gorre, 2007. http://d-nb.info/98780376X/04.

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20

Haigh, Mary K. "1/f noise in mercury cadmium telluride semiconductor diodes." Thesis, Heriot-Watt University, 2005. http://hdl.handle.net/10399/200.

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21

Santana-Corte, Juan Martin. "GaAs diodes in the relaxation regime used for radiation detection." Thesis, Lancaster University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387434.

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22

Kashefi-Naini, A. "A study of some transition metal-silicon Schottky barrier diodes." Thesis, University of Kent, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375200.

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23

盧志偉 and Chi-wai Lo. "Improvement of semiconductor laser diodes' characteristics by using diffused quantum wells structure." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31215592.

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24

Lo, Chi-wai. "Improvement of semiconductor laser diodes' characteristics by using diffused quantum wells structure /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19003341.

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25

CAMARGO, FABIOLA de A. "Laser de Nd:YVOsub(4) bombeado transversalmente em configuração com ângulo rasante interno." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11406.

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Made available in DSpace on 2014-10-09T12:51:35Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T13:58:17Z (GMT). No. of bitstreams: 0
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:03/10164-9
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26

Sakai, Joao Wesley Lopes. "Donor-assisted resonant tunnelling in semiconductor heterostructures." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387861.

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27

Woodworth, Sean C. Cassidy Daniel Thomas. "Design, theory, and applications of broad gain profile indium gallium arsenide phosphide diode lasers /." *McMaster only, 2005.

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28

Heard, David. "Structural and optical characterisation of Langmuir-Blodgett films for data storage applications." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257938.

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29

Milward, Jonathan Ray. "Electronic optical nonlinearities in ZnSe." Thesis, Heriot-Watt University, 1991. http://hdl.handle.net/10399/858.

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30

Hartnett, Kathleen A. "Streak camera analysis of dynamic characteristics of current modulated diode laser arrays /." Full text open access at:, 1988. http://content.ohsu.edu/u?/etd,160.

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31

Hamamoto, Kiichi. "Active multi-mode-interferometer laser diodes and semiconductor optical amplifiers /." Zürich, 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13822.

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32

Lock, Daren. "Investigations into the high power limitations of semiconductor laser diodes." Thesis, University of Surrey, 2005. http://epubs.surrey.ac.uk/711/.

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33

Lam, Sin Cho L. A. "Spectral gain studies for thermal effects in semiconductor laser diodes." Thesis, Cardiff University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383091.

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34

Lioliou, Grammatiki. "Wide bandgap semiconductor radiation detectors for extreme environments." Thesis, University of Sussex, 2017. http://sro.sussex.ac.uk/id/eprint/71077/.

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Wide bandgap semiconductor photodiodes were investigated for their suitability as radiation detectors for high temperature applications (≥ 20 °C), through measurements, calculations of key parameters of the devices, and relating the results back to the material, geometry of the detectors, environment under which the detectors were investigated, and previously published work. Three families of photodiodes were examined. 4H-SiC vertical Schottky UV photodiodes with Ni2Si interdigitated contacts were characterised for their response under dark and UV illumination. Electrical characterisation up to 120 °C and room temperature responsivity measurements (210 nm to 380 nm) suggested that the devices could operate at low UV light intensities, even at high visible and IR backgrounds without the use of filters, and at high temperatures. 4H-SiC Schottky photodiode detector arrays with planar thin NiSi contacts were investigated for X-ray (≤ 35 keV) detection and photon counting spectroscopy at 33 °C. The electrical characterisation of the devices up to 140 °C and subsequent analysis suggested that the devices are likely to operate as high temperature X-ray spectrometers. Results characterising GaAs p+-i-n+ mesa photodiode detectors for their room temperature visible and near infrared responsivity (580 nm to 870 nm), as well as their high temperature (≤ 60 °C) X-ray detection performance (at 5.9 keV) are presented. GaAs p+-i-n+ mesa photodiodes were also shown to be suitable for β- particle (electron) spectroscopy and X-ray fluorescence spectroscopy (≤ 21 keV) at 33 °C. The X-ray and electron spectroscopic measurements were supported by a comprehensive treatment of the noise components in charge sensitive preamplifiers. Calculations showed the potential benefits of using a SiC, rather than Si, JFET as the input transistor of such a preamplifier operating at high temperatures. The spectroscopic measurements, using both the 4H-SiC and GaAs photodiodes, are presented along with noise analysis to detangle the different noise components present in the reported spectrometers, identify the dominant source of noise, and suggest potential improvements for future spectrometers using the reported devices.
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35

Wölfl, Friedrich. "Intensity noise studies of semiconductor light emitters." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342990.

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36

Lochner, Zachary Meyer. "Green light emitting diodes and laser diodes grown by metalorganic chemical vapor deposition." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33827.

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This thesis describes the development of III-Nitride materials for light emitting applications. The goals of this research were to create and optimize a green light emitting diode (LED) and laser diode (LD). Metalorganic chemical vapor deposition (MOCVD) was the technique used to grow the epitaxial structures for these devices. The active regions of III-Nitride based LEDs are composed of InₓGa₁₋ₓN, the bandgap of which can be tuned to attain the desired wavelength depending on the percent composition of Indium. An issue with this design is that the optimal growth temperature of InGaN is lower than that of GaN, making the growth temperature of the top p-layers critical to the device performance. Thus, an InGaN:Mg layer was used as the hole injection and p-contact layers for a green led, which can be grown at a lower temperature than GaN:Mg in order to maintain the integrity of the active region. However, the use of InGaN comes with its own set of drawbacks, specifically the formation of V-defects. Several methods were investigated to suppress these defects such as graded p-layers, short period supper lattices, and native GaN substrates. As a result, LEDs emitting at ~532 nm were realized. The epitaxial structure for a III-Nitride LD is more complicated than that of an LED, and so it faces many of the same technical challenges and then some. Strain engineering and defect reduction were the primary focuses of optimization in this study. Superlattice based cladding layers, native GaN substrates, InGaN waveguides, and doping optimization were all utilized to lower the probability of defect formation. This thesis reports on the realization of a 454 nm LD, with higher wavelength devices to follow the same developmental path.
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37

Barlow, Mark Donald. "Metal-Semiconductor Contacts for Schottky Diode Fabrication." Youngstown State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1198114671.

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38

Liu, Piao. "Heterojunctions and Schottky Diodes on Semiconductor Nanowires for Solar Cell Applications." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/77.

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Photovoltaic devices are receiving growing interest in both industry and research institutions due to the great demand for clean and renewable energy. Among all types of solar cells, cadmium sulfide (CdS) – cadmium telluride (CdTe) and cadmium sulfide (CdS) - copper indium diselenide (CuInSe2 or CIS) heterojunctions based thin film solar cells are of great interest due to their high efficiency and low cost. Further improvement in power conversion efficiency over the traditional device structure can be achieved by tuning the optical and electric properties of the light absorption layer as well as the window layer, utilizing nano template-assisted patterning and fabrication. In this dissertation, simulation and calculation of photocurrent generation in nanowires (NW) based heterojunction structure indicated that an estimated 25% improvement in power conversion efficiency can be expected in nano CdS – CdTe solar cells. Two novel device configurations for CdTe solar cells were developed where the traditional thin film CdS window layer was replaced by nanowires of CdS, embedded in aluminum oxide matrix or free standing. Nanostructured devices of the two designs were fabricated and a power conversion efficiency value of 6.5% was achieved. Porous anodic aluminum oxide (AAO) was used as the template for device fabrication. A technology for removing the residual aluminum oxide barrier layer between indium tin oxide (ITO) substrate and AAO pores was developed. Causes and remedies for the non-uniform barrier layer were investigated, and barrier-free AAO on ITO substrate were obtained. Also, vertically aligned nanowire arrays of CIS of controllable diameter and length were produced by simultaneously electrodepositing Cu, In and Se from an acid bath into the AAO pores formed on top of an aluminum sheet. Ohmic contact to CIS was formed by depositing a 100 nm thick gold layer on top and thus a Schottky diode device of the Au/CIS nanowires/Al configuration was obtained. Material properties of all these nanowires were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), absorption measurement. Current-voltage (I-V), capacitance-voltage (C-V) and low-temperature measurements were performed for all types of devices and the results were analyzed to advance the understanding of electron transport in these nano-structured devices.
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39

Qu, Junling. "Colloidal semiconductor nanocrystals for optoelectronic applications : photodetectors and light emitting diodes." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS021.

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Les nanocristaux dont la dimension est inférieure à leur rayon de Bohr excitonique peuvent fournir des propriétés optoélectroniques accordables avec la taille. Cela permet d’obtenir des propriétés électroniques à façon. En particulier, le développement de la synthèse par voie colloïdale des nanocristaux en fait des briques élémentaires prometteuses pour des applications optoélectroniques à bas coût. Ma thèse cible deux aspects des dispositifs à base de nanocristaux: les photodétecteurs infrarouges et les diodes électroluminescentes (LED). Ma thèse est d'abord centrée sur la photodétection infrarouge sans métaux lourds utilisant soit la transition intrabande d'Ag2Se, soit des nanocristaux plasmoniques ITO. J'ai étudié leurs propriétés optiques et de transport ainsi que leur spectre électronique. J’ai ensuite testé leurs performances pour la photodétection infrarouge. Les performances obtenues sont mises en perspective par rapport à leurs homologues contenant des métaux lourds. Dans une seconde partie de ma thèse, je me focalise sur les LEDs à base de nanocristaux avec des longueurs d’onde visées à la fois dans le visible et le proche infrarouge. La LED visible conçue à l'aide de nanoplaquettes CdSe/CdZnS montre une faible tension de fonctionnement et la durée de vie la plus longue obtenue pour les LED à base de nanoplaquettes. Ensuite, cette LED est couplée à un photodétecteur PbS maison pour réaliser pour la première fois une communication de type LiFi tout nanocristal. Pour les LED proche infrarouge, j’ai utilisé HgTe comme matériau optiquement actif. En formant une hétérojonction à partir de HgTe / ZnO, une LED infrarouge lumineuse capable d'imagerie active est obtenue
Nanocrystals with a dimension below their excitonic Bohr radius can provide size-tunable optoelectronic properties, enabling on-demand tailoring of properties for specific applications. Especially, the advance of wet chemistry synthesis of colloidal nanocrystals makes them promising building blocks for the next-generation solution-processible low-cost optoelectronics such as light emitting, sensing, and harvesting. My thesis targets two aspects of the nanocrystal-based devices: infrared (IR) photodetector and light emitting diode (LED). My thesis is first focused on the heavy-metal-free IR photodetection using the intraband transition of self-doped Ag2Se or the plasmonic resonance of remotely doped ITO (tin doped indium oxide) nanocrystals. Before integrating them to photoconductive devices, I study their optical and transport properties as well as their energy spectra. I then test their IR photodetection performance and rationalize their weak performance compared with their heavy metal counterparts. In the second part of my thesis, I advance to the all-solution nanocrystal-based LEDs in the visible and SWIR, with an emphasis on their practical applications. The designed visible LED using CdSe/CdZnS nanoplatelets (NPLs) shows the lowest turn-on voltage and the longest lifetime for NPL-based LED. I also provide insights on the origin of efficiency droop. Then, this LED is coupled with a homemade PbS broadband photodetector to achieve, for the first time, an all-nanocrystal based LiFi-like communication setup. For SWIR LEDs, HgTe is used as IR emitter. By forming a HgTe/ZnO bulk heterojunction in the emitting layer, a bright SWIR LED capable of active imaging is obtained
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40

Kotitschke, Ralf Thomas. "The effects of band structure on recombination processes in narrow gap materials and laser diodes." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843643/.

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The work described in this thesis investigates the effects of bandstructure modifications, brought about by Landau confinement, hydrostatic pressure and uniaxial stress, on recombination processes in narrow-gap materials and laser diodes. The effects of Landau confinement on the characteristics of InSb-based emission devices operating at a wavelength of ~5mum at 77K were studied. The change in performance due to the magnetic field applied along both the cavity and the growth direction and thereby simulating quasi-quantum wire and quasi-quantum dot structures clearly demonstrated the benefits, such as reduced threshold and temperature sensitivity, gained by the reduced dimensionality. On the other hand, suppression of LO-phonon emission due to the discrete nature of the density of states was observed, for the first time, in an interband laser device. Interband recombination dynamics were studied in In1-xGaxSb and PbSe over a range of excited carrier densities and temperatures down to 30K. Detailed analysis of the results found that the Auger-1 mechanism is reduced in In1-xGaxSb as a function of Ga-fraction due to the increased bandgap energy, in good agreement with theoretical predictions. In PbSe, the Auger-1 rate was observed to dominate at low excited carrier concentrations in spite of near-mirror bands, and was found to be approximately constant between 300K and 70K and was seen to be quenched in the low temperature regime. Stimulated emission was seen to be the most efficient recombination mechanism at high excited carrier densities at low temperatures. The Auger coefficient in PbSe was found to be one to two orders of magnitude lower than for materials with a Kane band structure (Hg1-xCdxTe) with comparable bandgap. An experimental technique was developed which enables measurements at high hydrostatic pressures and high magnetic fields at low temperatures. Hydrostatic pressures were applied to a 1.5mum laser diode at different temperatures revealing the effects of pressure on the band structure and hence the laser characteristics. A visible laser diode was measured under the simultaneous application of hydrostatic pressure and uniaxial stress. The change in performance was satisfactorily explained in terms of leakage of carriers into the X-minimum in the cladding region, the process that has been suspected of being one of the major loss mechanisms in visible laser diodes. This copy of the thesis has been supplied on the condition that anyone who consults it is understood to recognise that the copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without the prior written consent of the author or the University (as may be appropriate).
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41

Jobe, Sean Richard Keali'i. "OPTIMIZATION OF GAN LASER DIODES USING 1D AND 2D OPTICAL SIMULATIONS." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/74.

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This paper studies the optical properties of a GaN Laser Diode (LD). Through simulation, the GaN LD is optimized for the best optical confinement factor. It is found that there are optimal thicknesses of each layer in the diode that yield the highest optical confinement factor. There is a strong relationship between the optical confinement factor and lasing threshold—a higher optical confinement factor results in a lower lasing threshold. Increasing optical confinement improves lasing efficiency. Blue LDs are important to the future of lighting sources as they represent the final color in the RGB spectrum that does not have a high efficiency solution. The modeled GaN LD emits blue light at around ~450nm. Each layer of the GaN LD is drawn in a model simulation program called LaserMOD created by RSOFT Design Group, Inc. By properly modifying the properties of each layer, an accurate model of the GaN LD is created and then simulated. This paper describes the steps taken to properly model and optimize the GaN LD in the 1D and 2D models.
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42

Thomschke, Michael. "Inverted Organic Light Emitting Diodes." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-106255.

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This study focuses on the investigation of the key parameters that determine the optical and electrical characteristics of inverted top-emitting organic light emitting diodes (OLED). A co-deposition of small molecules in vacuum is used to establish electrically doped films that are applied in n-i-p layered devices. The knowledge about the functionality of each layer and parameter is important to develop efficient strategies to reach outstanding device performances. In the first part, the thin film optics of top-emitting OLEDs are investigated, focusing on light extraction via cavity tuning, external outcoupling layers (capping layer), and the application of microlens films. Optical simulations are performed to determine the layer configuration with the maximum light extraction efficiency for monochrome phosphorescent devices. The peak efficiency is found at 35%, while varying the thickness of the charge transport layers, the semitransparent anode, and the capping layer simultaneously. Measurements of the spatial light distribution validate, that the capping layer influences the spectral width and the resonance wavelength of the extracted cavity mode, especially for TM polarization. Further, laminated microlens films are applied to benefit from strong microcavity effects in stacked OLEDs by spatial mixing of external and to some extend internal light modes. These findings are used to demonstrate white top-emitting OLEDs on opaque substrates showing power conversion efficiencies up to 30 lm/W and a color rendering index of 93, respectively. In the second part, the charge carrier management of n-i-p layered diodes is investigated as it strongly deviates from that of the p-i-n layered counterparts. The influence of the bottom cathode material and the electron transport layer is found to be negligible in terms of driving voltage, which means that the assumption of an ohmic bottom contact is valid. The hole transport and the charge carrier injection at the anode is much more sensitive to the evaporation sequence, especially when using hole transport materials with a glass transition temperature below 100°C. As a consequence, thermal annealing of fabricated inverted OLEDs is found to drastically improve the device electronics, resulting in lower driving voltages and an increased internal efficiency. The annealing effect on charge transport comes from a reduced charge accumulation due to an altered film morphology of the transport layers, which is proven for electrons and for holes independently. The thermal treatment can further lead to a device degradation. Finally, the thickness and the material of the blocking layers which usually control the charge confinement inside the OLED are found to influence the recombination much more effectively in inverted OLEDs compared to non-inverted ones.
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43

Zhou, Yi Park Minseo. "Bulk gallium nitride based electronic devices Schottky diodes, Schottky-type ultraviolet photodetectors and metal-oxide-semiconductor capacitors /." Auburn, Ala., 2007. http://hdl.handle.net/10415/1401.

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44

Lewis, Ryan B. "GaAs₁₋xBix light emitting diodes : a new long wavelength semiconductor light source." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/5823.

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GaAs₁₋xBix is an exciting new semiconductor material, which has been pro posed as a new material for infrared light emitting devices. Recent ad vancements in the growth of GaAs₁₋xBix films have made it possible to produce GaAs₁₋xBix light emitting diodes for the first time. Throughout this research we have grown, fabricated and characterized GaAs₁₋xBix light emitting diodes. Similarly structured InxGa₁₋xAs light emitting diodes were also produced and characterized for comparison to the GaAs₁₋xBix devices. Strong electroluminescence was obtained from GaAs₁₋xBix devices, showing two emission peaks, one corresponding to the GaAs₁₋xBix layer and the other to the GaAs cladding. Emission from InxGa₁₋x_As devices was about 100 times brighter than from GaAs₁₋xBix devices. Temperature dependent electroluminescence and photoluminescence measurements of a GaAs₁₋xBix light emitting diode were made and showed some unusual results. The wavelength of the peak in the electroluminescence from the GaAs₁₋xBix was independent of temperature in the range 100 K to 300 K while the GaAs peak shifted with temperature as expected. Photoluminescence measurements on the same structure show temperature dependence of the peak wavelength similar to the temperature dependence of GaAs.
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45

You, Budong. "Investigation of MOS-Gated Thyristors and Power Diodes." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/26094.

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The MOS-gated thyristors (MGT) refer to the class of power devices that combine the ease of a MOS gate control with the superior current carrying capability of a thyristor structure for high-power applications. The MOS-controlled thyristor (MCT) is a typical MGT device. A comprehensive investigation of the reverse-biased safe operating area (RBSOA) characteristics of the MCT has been undertaken. The electrical failure mechanisms of the MCT are discussed, and the relationship between the dynamic avalanche limited RBSOA boundary of the MCT and the lower open-base transistor is identified. An analytical model based on the dynamic current gain concept is proposed to characterize the open-base transistor. For the first time, a RBSOA characteristic equation is developed for the MCT and a unified view of the RBSOA characteristics of the MCT is presented. The fundamental characteristics of the MCT are compared to those of the insulated gate bipolar transistor (IGBT) at two levels: unit-cell and multi-cell. The investigation of the unit-cell level focuses on the tradeoff between the on-state voltage drop, the turn-off loss, and the RBSOA characteristic. The investigation of the multi-cell level reveals the fundamental difference between the MCT and the IGBT in handling the non-uniform turn-off caused by the internal propagation gate delay of a large-area device. Lack of current saturation capability is identified as the main reason for the severe degradation of the turn-off capability of a large-area multi-cell MCT. The current saturation and controlled turn-on capabilities can be realized in the MGT devices with dual operation modes. For the first time, a dual operation mode MCT developed with superior current saturation capability is used to demonstrate how the dual operation device can be beneficial in the switching circuit application. The maximum controllable current density (Jmcc) is the most important characteristic of the dual operation mode MGT devices. A first-order analytic model is developed to characterize the Jmcc of the dual operation mode MGT structures compatible with the IGBT fabrication process. A new device structure with improved Jmcc characteristics is proposed and verified by both simulation and experimental results. The dissertation also carries out a comprehensive investigation of the development of power diodes. A new power diode, called the Trench Bipolar Junction Diode (TBJD), which has superior dynamic characteristics over the conventional P-i-N diode, is proposed. The TBJD controls the anode injection efficiency of the diode by the action of a reverse active transistor structure integrated into its anode junction. The reverse active transistor helps tailor an optimized on-state carrier profile to improve the diode switching characteristics. A novel self-aligned process is developed to fabricate the TBJD. Experimental characterization of the fabricated TBJD devices shows that the TBJD achieves superior dynamic characteristics without sacrificing the on-state voltage drop and the leakage current characteristics.
Ph. D.
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46

Fenwick, William Edward. "Metalorganic chemical vapor deposition of gallium nitride on sacrificial substrates." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/34687.

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GaN-based light emitting diodes (LEDs) face several challenges if the technology is to make a significant impact on the solid state lighting market. The two most pressing of these challenges are cost and efficiency. The development of alternative substrate technologies shows promise toward addressing both of these challenges, as both GaN-based device technology and the associated metalorganic chemical vapor deposition (MOCVD) technology are already relatively mature. Zinc oxide (ZnO) and silicon (Si) are among the most promising alternative substrates for GaN epitaxy. This work focuses on the development of MOCVD growth processes to yield high quality GaN-based materials and devices on ZnO and Si. ZnO, because of its similar lattice constant and thermal expansion coefficient, is a promising substrate for growth of low defect-density GaN. The major hurdles for GaN growth on ZnO are the instability of ZnO in a hydrogen atmosphere and out-diffusion of zinc and oxygen from the substrate. A process was developed for the MOCVD growth of wurtzite GaN and InxGa1-xN on ZnO, and the structural and optical properties of these films were studied. High zinc and oxygen concentrations remained an issue, however, and the diffusion of zinc and oxygen into the subsequent GaN layer was studied more closely. Silicon is the most promising material for the development of an inexpensive, large-area substrate technology. The challenge in GaN growth on Si is the tensile strain induced by the lattice and thermal mismatch between GaN and Si. A thin atomic layer deposition (ALD)-grown Al2O3 interlayer was employed to relieve strain while also simplifying the growth process. While some strain was still observed, the oxide interlayer leads to an improvement in thin film quality and a reduction in both crack density and screw dislocation density in the GaN films. A comparison of GaN-based LEDs grown on sapphire and Al2O3/Si shows similar performance characteristics for both devices. IQE of the devices on silicon is ~32%, compared to ~37% on sapphire. These results show great promise toward an inexpensive, large-area, silicon-based substrate technology for MOCVD growth of GaN-based optoelectronic devices.
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47

Fix, Baptiste. "Diodes nanostructurées pour la détection infrarouge par absorption à deux photons." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX056/document.

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Mes travaux de thèses portent sur l'étude de la photodetection infrarouge par processus d'absorption à deux photons non-dégénérés (NDTPA) dans des diodes nanostructurées à grand gap. Ce concept innovant permet en effet la détection infrarouge sans avoir recours aux systèmes de refroidissement du détecteur.Dans un premier temps, je recherche les paramètres clefs de cette étude. Pour commencer, j'étudie, théoriquement et expérimentalement, la compétition entre deux processus d'absorption sub-gap : l'absorption à deux photons, qui est un processus non linéaire du troisième ordre, et l'absorption linéaire sub-gap sur les défauts du semiconducteur (PASRH). La faible efficacité du NDTPA m'a ensuite amené à étudier des nanostructures capables de concentrer le champs lumineux dans une jonction en semiconducteur, donc d'augmenter l'efficacité absorption.Dans un second temps, je présente la conception, la fabrication en salle blanche et la caractérisation de deux générations de diodes nanostructurées pour la détection infrarouge par NDTPA. Les diodes de première génération sont des jonctions PIN en InP dont l'électrode supérieure nanostructurée est mono-résonante à 3.39 µm. J'ai vérifié leurs propriétés électrique et optique sur un banc dédié que j'ai monté. Finalement, je démontre la détection d'un flux infrarouge à température ambiante par NDTPA et avec un rapport signal sur bruit de 15. Une caractérisation du photocourant mesuré permet de déterminer que la nanostructure permet un gain de 24 sur la génération de photocourant par NDTPA.Après une analyse de cette étude et de ses difficulté, je propose et fabrique une seconde génération de diode nanostructurée résonante aux longueurs d'onde de pompe et de signal. Ce nouveau design permet d'atteindre des gains théorique de l'ordre de 1500 sur la génération de photocourant par NDTPA tout en limitant le photocourant parasite généré par PASRH.Finalement, dans un dernier volet, je présente un nouveau type de nano résonateurs à haut facteur de qualité utilisé dans le cadre des diodes de seconde génération. J'en présente un modèle analytique ainsi que ses principales propriétés
My thesis work is focused on infrared photodetection through non-degenerated two photons absorption (NDTPA) in a nanostructured large band-gap diode. This innovative concept is an alternative scheme for infrared detection at high operating temperatures.In a first step I will search for the key parameters of this study. I start by studying, theoretically and experimentally, the competition between two sub-gap absorption processes : the NDTPA, which is a non-linear phenomena of the third order, and the linear sub-bandgap absorption on the semiconductors defects (PASRH). Steered by the intrinsically low absorption efficiency of NDTPA, I studied the amplification of photocurrent generation through the fields concentration induced by a nanostructure.In a second time, I present the computed design, the fabrication inside a clean-room and the characterisation of two generations of nanostructured diodes. The first generation diodes are PIN junctions made of InP whose nanostructured top electrodes are mono-resonant at the signal wavelength (3.39 µm). I checked their electrical and optical properties on a dedicated bench that I designed. Finaly I demonstrate an infrared detection at room temperature through NDTPA with a signal-to-noise ratio above 15. A gain of 24 on the generation of photocurrent is attributed to the nanostructure.After an analysis of this first study, I designed and fabricated a second generation of nanostructured diode which are resonant at both the signal and the pump wavelength. This new design can theoretically achieve a gain around 1500 on the generated photocurrent while keeping the parasite PASRH photocurrent under control.Finally in a last part, I study a new high-quality factor nano-resonator which has been used in the design of the second generations diodes. I present an analytical model as well as their principals properties
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48

Philbrick, Robert H. "Modeling of light absorption in solid state imagers /." Online version of thesis, 1990. http://hdl.handle.net/1850/10557.

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49

Barrow, David Antony. "Generation and detection of short optical pulses." Thesis, University of Glasgow, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360226.

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50

Коломієць, С. В., Д. І. Павлюченко, Лариса Валентинівна Однодворець, Лариса Валентиновна Однодворец, and Larysa Valentynivna Odnodvorets. "Дослідження вольт-амперних характеристик діодів різного функціонального призначення." Thesis, Видавництво СумДУ, 2012. http://essuir.sumdu.edu.ua/handle/123456789/27686.

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