Validation and optimization of a numerical model for heat and mass transport in a multi-zone furnace for the ammonothermal crystal growth

Art der Arbeit

Masterarbeit

Bearbeiter

Geng Chongwei

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. In crystal growth, technology development plays a crucial role for the process development, to obtain crystals of higher quality (crystalline perfection, purity, etc.). One key technology in this field is modelling and simulation of the growth furnace to understand the key parameters for controlling the thermal field. This allows for a targeted optimization of the furnace construction as well as the operating parameters during the crystal growth. In that work, an already existing numerical model will be experimentally validated. The focus of the study is the temperature field, in particular the temperature distribution on the reactor (autoclave) wall. The experimental validation will be conducted via thermocouples on the autoclave wall and at several positions in the gas phase. The multiphysics software CrysMAS (developed by Fraunhofer IISB) will be provided for the numerical study. Deviations between the experimentally obtained data and the simulation results will be evaluated, aiming for an understanding of their causes. If necessary, the model will be adapted. After that, the pros and cons of the investigated concept (furnace and thermal environment thereof) will be compared with other ammonothermal configurations found in the literature. The last step is then to optimize the control variables and to derive possible new steps in the technology development towards improved crystal growth conditions.

Ansprechpartner

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