ZnO films were deposited on a GaAs ridge structure using radio-frequency (rf)-magnetron sputtering. A SiO2 thin buffer layer was introduced to alleviate a thermal mismatching problem between the ZnO film and the GaAs substrate. Deposition parameters such as rf power, distance, and gas composition/pressure were optimized to obtain highly c-axis oriented and highly resistive ZnO films. Postdeposition anneal treatment at 430-degrees-C for 5-10 min was found to enhance c-axis orientation of the ZnO films dramatically and to reduce intrinsic stress significantly. Stress on the cleaved facet of the waveguide was imaged with a spatially resolved and polarization-resolved photoluminescence technique. The results showed that the GaAs mesa is stressed up to 1X10(9) dyn/cm2 (10(-3) strain) due to residual stress from the ZnO/SiO2/GaAs structure.