Presentation Information
[8a-N202-4]Transient Process Conditions during Ammonothermal Crystal Growth of GaN
〇Saskia Carola Schimmel1, Daisuke Tomida2, Kohei Shima3, Tohru Ishiguro3, Yoshio Honda2, Shigefusa F. Chichibu3, Hiroshi Amano2 (1.FAU Erlangen-Nuremberg, 2.Nagoya Univ., 3.Tohoku Univ.)
Keywords:
bulk crystal,crystal growth,nitride process technology and characterization
The ammonothermal method is a key technology for producing gallium nitride bulk crystals. In this contribution, we elucidate the changes of thermal field and fluid flow during the transition from etch-back to growth conditions. This transition is controlled by an inversion of the set temperatures of the heaters. This study focuses on the transient conditions inside the autoclave. The temperature difference between nutrient and seed depends stongly on seed position, particularly at quasi-stable conditions for etch-back and crystal growth, respectively. The simulation result is in clear agreement with the seed position dependency of the remaining thickness of seeds and the growth rates that were experimentally determined from cleavage planes of crystals grown at the respective position. An insight gained solely via the numerical simulations is that during the set temperature inversion process, significant temperature differences occur between seeds and surrounding fluid.