HIGH-RESOLUTION X-RAY-DIFFRACTION ANALYSIS OF CUBIC GAN GROWN ON (001)GAAS BY RF-RADICAL SOURCE MOLECULAR-BEAM EPITAXY

Cubic GaN epilayers were grown on atomic hydrogen treated (0 0 1)GaAs substrates by RF-radical source molecular beam epitaxy. The crystallin e quality was characterized by a high-resolution X-ray diffractometer. It was found that high-quality c-GaN can be grown at temperatures abo ve 680 degrees C; the FWHM of (0 0 2)GaN rocking curve was as small as 80-90 arcsec. In order to further precisely investigate how and to wh at extent the h-GaN phase is included in the c-GaN layer, the X-ray re ciprocal space maps were measured for the X-ray beams incident along b oth [1 1 0] and [1 (1) over bar 0] azimuths. It was found that the sta cking faults exist predominantly on {1 1 1}A planes. The inclusion of h-GaN was estimated by comparing the integrated XRD intensities for h- GaN {1 0 (1) over bar 1} and c-GaN(0 0 2) planes. It was found that th e inclusion of h-GaN phase drastically decreased with increasing growt h temperature above 680 degrees C to reach about 4 x 10(-3) (or below) at temperatures of 710-740 degrees C. (C) 1998 Elsevier Science B.V. All rights reserved.