High quality GaN epitaxial layers were obtained with AlxGa1-xN buffer layers on 6H-SiC substrates. The low-pressure metalorganic chemical vapor deposition (LP-MOCVD) method was used. The 500 Angstrom thick buffer layers of AlxGa1-xN (0 less than or equal to x less than or equal to 1) were deposited on SiC substrates at 1025 degrees C. The FWHM of GaN (0004) X-ray curves are 2-3 arcmin, which vary with the Al content in AlxGa1-xN buffer layers. An optimum Al content is found to be 0.18. The best GaN epitaxial film has the mobility and carrier concentration about 564 cm(2) V-1 s(-1) and 1.6 x 10(17) cm(-3) at 300 K. The splitting diffraction angle between GaN and AlxGa1-xN were also analyzed from X-ray diffraction curves. (C) 1997 Elsevier Science S.A.
MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY