Ga Polarity Preference in Halide Vapor Phase Epitaxy of GaN on a GaAs (111)B: As Polar Substrate

Halide vapor phase epitaxy (HVPE) of hexagonal GaN can give a high growth rate with high crystal quality. To clarify the reason, the polarity of GaN grown on GaAs (111)A and (111)B surfaces was investigated. It was found that a low temperature GaN buffer layer sometimes exhibits N polarity by the treatment of the GaAs (111)B surface with ammonia (NH3), but GaN grown on it at high temperatures always exhibits Ga polarity independently of the polarity of the buffer layer. This is probably due to the fact that the HVPE is surface kinetic limited growth with the reduction of GaCl.