Dependence of orientation and electrical properties in sputtered ZnO upon deposition conditions and substrate

The authors have studied how orientation of planar magnetron sputtered ZnO varies as a function of radius from the center of the sputter target. They show that orientation deviates from normal with increasing radius from center, even on substrates parallel to the sputter cathode. The ZnO was deposited upon C-axis normal sapphire (Al₂O₃), fused quartz, and 111-Si under varied conditions, including variations in temperature, gas flow rate, sputter power, radial position relative to target center, and substrate angle. Production of high-quality ZnO, as evidenced by the X-ray rocking curve, is demonstrated. The ZnO quality is correlated to composition by stoichiometric measurements. Changes in orientation angle, crystal quality, and deposition angle with increased radius are shown and compared with computer simulations of the extended source.