DEPENDENCE OF THE HVPE GAN EPILAYER ON GAN BUFFER LAYER FOR GAN DIRECT GROWTH ON (001)GAAS SUBSTRATE

Cubic GaN was grown on (001) GaAs substrates by hydride vapor phase ep itaxy (HVPE) with a buffer layer grown by low temperature HVPE. The cr ystalline structure of the GaN buffer layer is studied using reflectio n high-energy electron diffraction (RHEED). The GaN layers were grown at 800 degrees C on the buffer layer with various growth temperatures and thicknesses. The optimum thickness of the buffer layer grown at 50 0 degrees C to obtain a cubic GaN layer was found to be 60 nm in our c ase. When the buffer layer was grown at 525 degrees C, however, the fu ll width at half-maximum (FWHM) of the X-ray diffraction (XRD) pattern was 21.2 min, which is the narrowest ever reported, as far as we know . Furthermore, it was demonstrated that a single crystalline GaN buffe r layer was necessary to obtain high-quality thick cubic GaN. (C) 1997 Elsevier Science Ltd.