Influence of carrier gas on the morphology and structure of GaN layers grown on sapphire substrate by six-wafer metal organic chemical vapor deposition system

The influence of hydrogen and nitrogen III-carrier gas mixture on the GaN l ayers grown at a high temperature of 1100 degreesC by a novel six-wafer met al-organic chemical vapor deposition (MOCVD) were studied using optical mic roscopy, X-ray diffraction (XRD), and photoluminescence (PL). The different ratio of nitrogen and hydrogen of III-carrier gas strongly affect the grow th mechanism of GaN layers. In the case of higher ratio of N-2/(N-2 + H-2), the surface shows a hillock morphology. On the other hand, with decreasing the flow rate of N-2 to a smaller ratio of N-2/(N-2 + H-2), the surface sh ows a mirror like morphology. In this case, the growth rate was also decrea sed. The measurement of X-ray diffraction (XRD) shows that the FWHM of XRD rocking curve of sample grown with smaller flow rate of N-2 becomes wider. (C) 2001 Elsevier Science B.V. All rights reserved.