SURFACE-MORPHOLOGY STUDY FOR HEXAGONAL GAN GROWN ON GAAS(100) SUBSTRATES BY HYDRIDE VAPOR-PHASE EPITAXY

The surface morphology of hexagonal (h-) GaN layers grown by hydride v apor phase epitaxy on GaAs (100) substrates with several misorientatio n angles and directions was examined. The surface morphology of the h- GaN epitaxial layers was very rough on GaAs (100) exact substrates and GaAs (100) substrates misoriented toward the [111]A direction. The mo rphology was greatly improved on GaAs (100) substrates misoriented tow ard the [111]B direction, depending on the misorientation angles. The best surface morphology in our experiment was obtained on GaAs (100) s ubstrates misoriented by 15.8 degrees toward the [111]B direction. It was also found that a Ga-rich surface was favorable for GaN growth wit h good morphology.