Published online by Cambridge University Press: 17 March 2011
Dependence of hexagonal GaN polarity on the polarity of GaAs (111) substrates was investigated by CAICISS for HVPE and MOVPE. Although polarity of MOVPE GaN followed the polarity of GaAs substrate; Ga polar for (111)A and N polar for (111)B, both layers of HVPE GaN grown on GaAs (111)A & B surfaces were Ga 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 results can be understood by difference of the buffer layers and difference of growth kinetics between HVPE and MOVPE.