Formation of c-axis oriented ZnO optical waveguides by radio-frequency magnetron sputtering

ZnO/Mg0.16Zn0.84O (ZnO/MgZnO) films are fabricated on x-cut and z-cut LiNbO3 (LN) substrates by radio-frequency magnetron sputtering. High transparencies are confirmed by a spectrophotometer. X-ray diffraction (XRD) spectra show that all the films are c-axis oriented. The waveguiding properties, as well as the refractive indices and thickness of the films are demonstrated and determined by prism coupling. Both transverse electric (TE) and transverse magnetic (TM) modes are measured at lambda=0.633 mum and 1.539 mum, respectively. The waveguide loss is measured at lambda=0.633 mum with a fiber probe technique. The experimental results show that high optical quality ZnO films can be obtained with MgZnO buffer layers.