First-principles simulation of the chemical reactions in GaN growth from Ga₂O

Abstract

First-principles calculation has been used to analyze the chemical reaction path in GaN epitaxial crystallization. The intrinsic reaction coordinates (IRC) have been searched for and the reaction path from Ga2O, which is a raw material of GaN, has been clarified. Ga2O is reacted with NH3 to form GaN, H2O, and H2. There is no residual solid product in the vapor process apart from GaN and the deposition on the chamber wall can be reduced. Thus, long-time continuous crystal growth can be executed. This is an advantage for producing a freestanding GaN substrate and reduces production costs. We have found that the chemical reactions proceed to GaNH2 in the gas-phase reactions. We have also found that GaNH2 molecules are finally adsorbed on the GaN substrate. The reaction path obtained in this work was exothermic as a whole and did not include any fatally large activation barrier. It is suggested that production with this process can be stably continued.