Advancement of a highly improved autoclave purification process for the ammonothermal growth of high-purity nitrides 

Art der Arbeit

Masterarbeit

Bearbeiter

Yi Wei

Beschreibung der Arbeit

Nitride semiconductors, as wide-bandgap semiconductors, are playing an increasingly important role as substrate materials for power electronic components. 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 structural quality, as well as its scalability to grow multiple crystals simultaneously. A disadvantage of the method is the currently unavoidable high level of impurities. A major impurity is oxygen. This high oxygen contamination impairs the dopability of the nitride semiconductors themselves and also influences the formation of further crystal defects. To further reduce the oxygen level, this work aims to develop a significantly improved autoclave purification process. For this purpose, autoclaves (reaction vessels) are to be heated prior to the growth using an experimental setup. During this heating process, the atmosphere in the autoclave will be varied from vacuum to a reducing atmosphere and/or inert gas atmosphere. The effectiveness of the purification process will be evaluated. For this purpose, the desorbing O2 and H2O gas will be analyzed using a trace moisture sensor (based on P2O5) and an O2 sensor (zirconia oxygen sensor). The data will then be interpreted using vapor pressure curves to optimize the purification process. Once an optimized purification process has been found, GaN-crystals will be grown to verify and quantify the effectiveness of the purification process on the impurities incorporated into the crystal.

Ansprechpartner

Thomas Wostatek (M. Sc.) Dr.-Ing. Saskia Schimmel