Polarity of Hexagonal GaN Grown on GaAs (111)A and (111)B Surfaces by HVPE and Movpe

Polarity of hexagonal GaN grown by HVPE and MOVPE on GaAs (111) substrates was investigated by CAICISS (Coaxial Impact Collision Ion Scattering Spectroscopy). Both layers of HVPE GaN grown on GaAs (111) A — Ga surface — and (111)B — As surface — were Ga polarity. On the other hand, MOVPE GaN grown on the (111)B showed N polarity whereas the layer grown on the (111)A showed Ga polarity, inheriting the substrate polarity. Crystal quality was better for Ga polarity layers than for N polarity layers for MOVPE. However, Ga polar GaN grown on GaAs (111)B by HVPE had better crystal quality than that on the (111)A. These differences may be attributed to difference of the buffer layers and difference of growth mode between HVPE and MOVPE.