Evaluation of ZnO substrates for homoepitaxy

Abstract

Commercial {0 0 0 1} oriented ZnO wafers grown by the hydrothermal and seeded physical vapor transport (SPVT) technique are evaluated from the viewpoint of their use in ZnO homoepitaxy. No significant difference in lattice parameters was found. The surface damage due to mechanical polishing is identified by high-resolution X-ray diffraction and the surface roughness is measured by atomic force microscopy. The SPVT substrates are superior in surface quality compared to the hydrothermal substrates, because no damaged surface layer or scratches were found. However, with additional polishing, for both kinds of substrates the surface damage could be removed. Triple-axis ω-scans were performed for different symmetrical reflections (0 0 l) with l=2,4,6. From these measurements, it could be concluded that while the tilt of mosaic areas in the crystals is almost the same (≈60 arcsec) for both kinds, the domain size is estimated to be smaller for the SPVT compared to the hydrothermal substrates.