GaN films were grown on (111)GaAs substrates by radio frequency magnetron sputtering in an ambient or argon and nitrogen, using a pare gallium target. The crystal structure and crystallinity of the GaN films were investigated as functions of substrate temperature, sputtering pressure, and nitrogen content in plasma. For substrate temperatures below 500degreesC, no diffraction peak or GaN in the theta-2theta patterns was observed, suggesting the film is amorphous. However, when the temperature was increased up to 700degreesC, single crystal GaN epitaxial layers with smooth surface could be grown on (111)GaAs substrates. Higher sputtering pressures were needed to obtain single crystal GaN on (111)GaAs than for sapphire substrate. The crystallinity of GaN tended to improve gradually with decreasing nitrogen concentration. (C) 2002 Elsevier Science B.V. All rights reserved.