High rate epitaxial growth of ZnO films on sapphire by planar magnetron rf sputtering system

Single crystal films of (11$\text{2}$0)ZnO are obtained on (01$\text{1}$2) sapphire at a deposition rate of 2 μm/h at a substrate temperature of 210–260°C by using a planar magnetron type high rate and low substrate temperature rf sputtering system. The surface of the film is so smooth that it can be used as an optical waveguide without post-deposition treatment. However, the films so far obtained have considerably higher optical waveguide loss than that of chemically vapor deposited films on the same face of sapphire.