Pressure effects in ZnO films using off-axis sputtering deposition

ZnO films are deposited on (0 0 0 1) sapphire and quartz substrates using the off-axis reactive magnetron sputtering deposition. Based on film thickness measurements, three transport regions of sputtered particles are observed when films are deposited in the pressure regions of 5-150 mTorr, X-ray diffraction, scanning probes microscopy, and electrical measurements are also used to characterize these films. The full-width at half-maximum of theta-rocking curves for epitaxial films is less than 0.5 degrees. In textured films, it rises to several degrees. The epitaxial films deposited at high pressure reveal a flat surface with some hexagonal facets. The density of hexagonal facets decreases when the growth pressure is reduced. The resistivity of these epitaxial films also depends on the growth pressures. A relationship between the pressure effects and film properties are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.