Vishvas Nanjunda Swamy – Wide bandgap semiconductor, particularly Silicon Carbide (SiC), based electronic devices and circuits are presently being developed for use in hightemperature, high-power, and high-radiation conditions under which conventional semiconductors cannot adequately perform[1]. This study highlights the trade-offs between power efficiency, speed, and area. Utilizing the second generation of the process design kit…
Yi Wei – In ammonothermal GaN crystal growth, residual moisture and oxygen species adsorbed on internal autoclave surfaces can severely degrade crystal quality. This thesis presents a high-temperature autoclave purification procedure aimed at eliminating these impurities from the growth environment. We purified the autoclave through inert-gas flushing combined with a multi-stage heating procedure. The heating…
Geng Chongwei – In this study, a two-dimensional axisymmetric model of a three-zone furnace for the ammonothermal growth of nitride crystals was developed using CrysMAS software. The geometry of the model was constructed to closely match that of the real furnace, and the temperature boundary conditions were defined based on actual measurements at the furnace…
Johannes Bauer – Diese Arbeit befasst sich mit der Modellierung von Mikrospektroskopiemessungen. Das Ziel ist, erstmals die komplexen Brechungsindizes eines Materials aus dessen Reflektanz- und Transmittanzspektren zu bestimmen. Der von der Mikrospektroskopie ermöglichte kleine Messfleck erlaubt die Untersuchung von Proben mit lateralen Dimensionen im Mikrometerbereich, was diese zu einer für die Mikroelektronik interessanten Charakterisierungsmethode macht….
Manan Rupesh Nandwana – In this project work the main focus is on developing a Python-based Image processing tool for analyzing X-ray images. The goal is simple to generate spatially resolved concentration maps of solutes during ammonothermal synthesis experiments. Growing high-quality gallium nitride (GaN) crystals is typically done using the ammonothermal method, which in-volves extreme…
Maitri Bharatbhai Savani – This work examines the solubility of gallium nitride (GaN) in supercritical ammonia to understand its behavior under ammonothermal growth conditions. A systematic evaluation and comparison of thermodynamic and empirical models was conducted. Results demonstrate that density-based models (Chrastil, Mendez-Santiago-Teja) correlate GaN solubility with significantly higher accuracy than temperature-based approaches (van’t Hoff,…
Anu Anna Koshy — Silicon carbide (4H-SiC) MOSFET devices are essential for high-power and potentially also for high-temperature applications. However, especially the reliability of their gate oxides at high temperatures has not yet been extensively studied. This thesis investigates the gate oxide reliability by analysing the time-dependent dielectric breakdown (TDDB) behaviour of MOSFET and MOSCAP…
Fabian Schmid — Das Kontaktieren von Halbleiter Chips ist eine essenzielle Voraussetzung für die Charakterisierung und Messung von Bauelementen. Dabei kann es notwendig sein, dass aus Platzgründen für Messplätze nur eine feste Verdrahtung in Form von Wirebonds in Frage kommt. Dafür müssen auf dem Chip entsprechende Kontaktpads mit ausreichend Platz zur Verfügung gestellt werden, damit…
Michael Mischin – Through a combination of experimental analysis and theoretical modeling, this work contributes to the optimization of fabrication processes in SiC-based power devices. The findings demonstrate the advantages of optical characterization techniques for non-destructive and high-precision measurements of layer thickness to enhance the performance and cost-effectiveness of SiC trench-MOSFETs. Previous research has shown…
Tian Lu – The ammonothermal method is widely considered to be one of the most promising techniques for growing nitride semiconductor crystals. However, a major challenge lies in the high levels of oxygen and water impurities that are commonly present in the resulting crystals. This study therefore aims to develop an efficient autoclave cleaning process…
Niklas Kardatzki – Nanostrukturen wie Nanosäulen/-löcher, Nanolinienstrukturen oder Nanopartikel haben sich als leistungsfähige Komponenten in den Bereichen Photonik, MEMS/MOEMS/NEMS, biokompatible Sensoren und der Quantensensorik erwiesen. Daher stellt die Strukturierung von Wirtsmaterialien wie Silizium (Si) und Siliziumcarbid (SiC) einen entscheidenden Schritt dar. Für die Übertragung und Realisierung benötigter Nanostrukturen dienen lithographische Techniken wie die Elektronenstrahl-Lithographie (EBL,…
Jun Zheng – Nitride semiconductors as semiconductors with a large band gap are playing an increasingly important role as substrate material for power electronic devices. Ammonothermal crystal growth is a promising growth method for a wide variety of nitride semiconductor materials. The advantage of this method is the ability to produce crystals with very high…
Sai Kumar Eedupalli — This project investigates the structural integrity and failure mechanisms of optical cell win-dows used in high-pressure, high-temperature ammonothermal reactors for gallium nitride (GaN) crystal growth. Ammonothermal synthesis operates under extreme conditions—pres-sures of 100–300 MPa and temperatures up to 600 °C—requiring robust optical viewing win-dows to enable in-situ monitoring. These windows, typically…
Ravi Jayantibhai Domadiya — Dieser Bericht untersucht das strukturelle und thermische Verhalten eines hermetisch abgedichteten, silberausgekleideten ammonothermalen Autoklaven, der für das hochreine Wachstum von Galliumnitrid (GaN)-Kristallen unter extremen Druck- und Temperaturbedingungen ausgelegt ist. Die Forschung kombiniert präzise CAD-Modellierung mit fortschrittlichen Finite-Elemente-Simulationen, um die Wechselwirkungen zwischen Druckbehälterkomponenten, Dichtleistung und Materialkompatibilität zu erfassen. Die Autoklavenbaugruppe umfasst eine…
