Thermodynamic considerations of the vapor phase reactions in III-nitride metal organic vapor phase epitaxy

We analyzed the metal organic vapor phase epitaxial growth mechanism of the III-nitride semiconductors GaN, AlN, and InN by first-principles calculations and thermodynamic analyses. In these analyses, we investigated the decomposition processes of the group III source gases X(CH3)(3) (X = Ga, Al, In) at finite temperatures and determined whether the (CH3)(2)GaNH2 adduct can be formed or not. The results of our calculations show that the (CH3)(2)GaNH2 adduct cannot be formed in the gas phase in GaN metal organic vapor phase epitaxy (MOVPE), whereas, in AlN MOVPE, the formation of the (CH3)(2)AlNH2 adduct in the gas phase is exclusive. In the case of GaN MOVPE, trimethylgallium (TMG, [Ga(CH3)(3)]) decomposition into Ga gas on the growth surface with the assistance of H-2 carrier gas, instead of the formation of the (CH3)(2)GaNH2 adduct, occurs almost exclusively. Moreover, in the case of InN MOVPE, the formation of the (CH3)(2)InNH2 adduct does not occur and it is relatively easy to produce In gas even without H-2 in the carrier gas. (C) 2017 The Japan Society of Applied Physics