Chloride vapour phase epitaxial growth of GaN on (0001) sapphire substrate has been investigated at various growth temperatures. The crystalline and optical qualities of the GaN have been improved significantly by increasing the growth temperature from 925degreesC to 990degreesC. For GaN films grown at 990degreesC, the FWHM for the (0002) peak of the HRXRD curve have been determined. The GaN films show band-edge emission dominated PL at low temperature. From the phi-scan studies, it is confirmed that the GaN films grown on (0001) sapphire substrate are single crystalline. (C) 2004 Elsevier B.V. All rights reserved.