Middle-frequency magnetron sputtering for GaN growth

A middle-frequency magnetron sputtering system was designed and constructed for GaN growth, in which a pair of back cooled pool-shaped twin magnetrons were used for Ga metal targets. GaN films were prepared using this system under various gas pressure (0.5-3.0 Pa) in a mixture of N-2 and Ar with N-2/Ar ratio of 6:1. X-ray diffraction showed that the GaN films had a strong (0002) orientation, and the film deposited at 1.5 Pa had two more weak peaks attributed to (10 (1) over bar2) and (10 (1) over bar3). The full width at half maximum (FWHM) of the (0 0 0 2) peak for the GaN film deposited at 1.5 Pa and 0.5 Pa is similar to 721 and similar to 986 arcsec, respectively. The deposition rate was in the range of 43.5-87.8 nm/min and was mainly influenced by the deposition pressure. The films deposited at higher pressures are columnar in structure. A root-mean-square roughness of 4.4 nm was obtained from the atomic force microscopy (AFM) surface morphology of the film deposited at 0.5 Pa. (c) 2007 Elsevier B.V. All rights reserved.