Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 116 for “"Algan"”.
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AlGaN/GaN-based power semiconductor switches
AlGaN/GaN-based high-electron-mobility transistors (HEMTs) have great potential for their use as high efficiency and high speed power semiconductor switches, thanks to their high breakdown electric field, mobility and charge density. The ability to grow these devices on large-diameter Si wafers …
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Persistente Photoleitfähigkeit indünnen GaN- und AlGaN-Schichten
Galliumnitrid (GaN) wird In den nächsten Jahren Im Bereich optoelektronischer Anwendungen das dominierende Materialsystem für Bauteile wie Leuchtdioden und Halbleiterlaserdioden kurzwelligen (blau bis ultraviolett) sein. Rahmen dieser Arbeit untersuche ich Phänomen der persistenten …
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AlGaN/GaN heterostructures for enhancement mode transistors
… è la possibilità di crescere eterostrutture AlGaN/GaN, in cui si forma un gas bidimensionale di elettroni (2DEG). Basandosi sulla presenza del 2DEG, le eterostrutture AlGaN/GaN sono particolarmente interessanti per la realizzazione di transistori ad elevata mobilità di elettroni (HEMT). …
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AlGaN/GaN HFET with composite 'slow/fast' gate
<p>The remarkable properties of AlGaN/GaN heterojunction field effect transistors (HFET) include a record high-density two dimensional electron gas (2DEG) channel, high breakdown fields, temperature stability and chemical robustness. Radio Frequency (RF) switches based on such HFETs demonstrate …
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Entwicklung von optisch pumpbaren UVC-Lasern auf AlGaN-Basis
… des Heterostrukturdesigns auf optisch gepumpte AlGaN-Laser mit Emissionswellenlängen im Bereich von 240 nm untersucht. Dabei wurden neue Erkenntnisse über elektrische und optische Verlustmechanismen gewonnen, die über den konkreten Anwendungsfall hinaus für AlGaN-Heterostrukturen relevant sind. …
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Structural and Morphological Analyses of Aln and Algan Layers
<p>III-nitride semiconductors based Deep UV LEDs are the prospective candidates to replace the traditional UV sources, such as mercury vapor lamps, used in the applications of water and air purification, germicidal and biomedical instrumentation systems and others. Due to the lack of native …
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Preparation and characterization of AlGaN structures for UVA LEDs
… two particular research questions i.e.: a) Since AlGaN is routinely used as an electron-blocking layer in visible and UV LEDs, does it act as such and how effective is it? b) How to achieve a low dislocation density template for UV (310-350 nm) LEDs where no native substrates for homoepitaxy are …
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Processing technology for high quality AlGaN/GaN MOSHEMT interfaces
Gallium Nitride (GaN) based high electron mobility transistors (HEMTs) are very promising for applications requiring high power and high operating frequencies due to its intrinsic material properties like the high electron mobility, large critical electric field and large carrier concentration. For …
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Self-aligned AlGaN/GaN transistors for sub-mm wave applications
… work done towards realizing self-aligned AlGaN/GaN high electron mobility transistors (HEMTs). Self-aligned transistors are important for improving the frequency of AlGaN/GaN HEMTs by reducing source and drain access resistance. The eventual fabrication of self-aligned transistors required …
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Fabrication and characterization of advanced ALGaN/GaN high-electron-mobility transistors
… to enhance the electrical characteristics of AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs). Chapter 2 reports the development of in situ vacuum anneal and SiH4 or SiH4+NH3 passivation to realize high quality metal gate/high-k dielectric stacks on GaN …
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Process Development and Characterization of AlGaN/GaN Heterostructure Field-Effect Transistors
The fabrication of AlGaN/GaN HFETs entailed first developing fundamental processing techniques such as isolation etching, low-resistance drain/source ohmic contacts, and Schottky gate formation. These efforts along with related processing issues will be discussed. Devices were then fabricated on …
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Substrate Impurity Incorporation Mitigation for Improved AlGaN/GaN-ON-Si RF Performance
… improved. As a result, the RF signal loss on AlGaN/GaN on Silicon materials is reduced substantially, well below 0.4 dB/mm for frequencies up to 50 GHz, compared to conventional AlGaN/GaN on Silicon heterostructures. For AlGaN/GaN HEMTs, this improvement of the RF performance is critical for …
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HIGH POWER ALGAN BASED DEEP UV LED LAMPS: DESIGN, FABRICATION AND CHARACTERIZATION
<p>Deep ultraviolet light sources wavelength ranging from 250 - 365 nm are used in many applications including water/air purification, analytical scientific instrumentation, bio-agent detection systems, and emerging medical instrumentation. Current UV-LEDs are limited in the market penetration due …
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Thermal Performance of AlGaN/GaN Based Power Switching Devices for Transformerless Inverters
… Nitride (GaN) and Aluminum Gallium Nitride (AlGaN) have superior material properties as compared to Silicon (Si) like higher electrical breakdown voltages and bandgap energies as well as lower leakage currents as compared to Si which make them ideal to operate at higher voltage with lower …
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Surface and mechanical stress effects in AlGaN/GaN high electron mobility transistors
… The first part of this thesis discusses planar AlGaN/GaN transistors. GaN is a piezoelectric material, and changes in mechanical stress result in a change in the charge density which in turn affects the maximum current in AlGaN/GaN transistors. Finite element modelling techniques were applied to …
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Impact of electrochemical process on the degradation mechanisms of AlGaN/GaN HEMTs
AlGaN/GaN high electron mobility transistors (HEMTs) constitute a new generation of transistors with excellent electrical characteristics and great potential to replace silicon technology in the future, especially in high power and high frequency applications. However, the poor long term …
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Design, Epitaxie und Charakterisierung AlGaN-basierter Leuchtdioden mit Emissionswellenlängen unterhalb von 250 nm
… Arbeit befasst sich mit der Realisierung von AlGaN-basierten ultravioletten Leuchtdioden (LEDs) mit Emissionswellenlängen unterhalb von 250 nm sowie der Analyse ihrer strukturellen und elektrooptischen Eigenschaften. Ziel war es, eine LED mit einer mit möglichst maximaler spektraler …
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AlGaN/GaN Dual Channel HFETs and Realization of GaN Devices on different substrates
… further reduce the hot phonon lifetime, a novel AlGaN/GaN dual channel HFET structure has been proposed. The growth, fabrication and characterization of such a AlGaN/GaN dual channel HFET structure has been carried out. Conventionally GaN-based light emitting diodes and laser diodes are grown and …
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Advanced process development for contacts to algan/gan high electron mobility transistors (HEMTS)
… studied as Schottky metallizations to GaN and AlGaN/GaN heterostructures. Ni/Au, Ni/Pt/Au, Ir/Au, Ir/Pt/Au and Pt/Au Schottky diodes were fabricated on GaN and AlGaN/GaN substrates. Schottky barrier heights ranging from 0.8 to 0.9 eV were obtained as-deposited on GaN with ideality factors of …
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