Effect of thermal treatment on ZnO substrate for epitaxial growth

ZnO is a highly efficient photon emitter, and has optical and piezoelectric properties that are attractive for a variety of applications in sensors and potentially in optoelectronic devices such as emitters. Due to its identical stacking order and close lattice match to GaN, it is also being developed as a substrate material for GaN epitaxy. However, the surface finish of the ZnO is such that much of the damage induced by sawing and follow up mechanical polishing remains. A thermal treatment method has been developed to eliminate surface damage on the 0 face of ZnO (000bar1) to prepare it for epitaxial growth. Atomic force microscopy images of ZnO (000bar1) annealed at 1050 C for 3 h etc. show that residual scratches from mechanical polishing are removed and atomically flat, terrace-like surfaces are attained. In addition, low-temperature photoluminescence and high-resolution XRD measurements were used to investigate the effect of annealing on ZnO substrates. 19 refs.