A Study On Initial Nucleation Using An Ultra Thin Amorphous Buffer Layer For The Growth Of Gan On Al2o3(0001) By Molecular Beam Epitaxy

Detailed investigation of Al2O3 pre-treatment and initial nucleation process were performed in order to grow a high quality GaN thin film on Al2O3(0001) by molecular beam epitaxy. The atomic step of an Al2O3 surface was successfully obtained by chemical etching using H3PO4:H2SO4. It was found that a very thin (26 Angstrom) amorphous buffer layer of atomic steps could form a uniform nucleation which consists of minute nuclei (RMS = 0.17 nm). The epilayer, which grew on this nucleation layer showed a significant improvement in crystal quality. Band edge emission (357 nm/FWHM = 22meV) without any deep emission band was observed with low temperature photoluminescence and the FWHM of the X-ray rocking curve was 20 arcmin.