Contact-induced damage was studied in single-crystal (wurtzite) ZnO by cross-sectional transmission electron microscopy and scanning cathodoluminescence monochromatic imaging. cross-sectional transmission electron microscopy reveals that the prime deformation mechanism in ZnO was the nucleation of slip on both the basal and pyramidal planes. Some indication of dislocation pinning was observed on the basal slip planes. No evidence of either a phase transformation or cracking was observed by cross-sectional transmission electron microscopy in samples loaded up to 50mN with a roughly 4.2µm radius spherical indenter. Cathodoluminescence imaging reveals a quenching of near-gap emission by deformation-produced defects. Both cross-sectional transmission electron microscopy and cathodoluminescence showed that this comparatively soft material exhibited extensive deformation damage and that defects could propagate well beyond the deformed volume under contact.

Contact-Induced Defect Propagation in ZnO. J.E.Bradby, S.O.Kucheyev, J.S.Williams, C.Jagadish, M.V.Swain, P.Munroe, M.R.Phillips: Applied Physics Letters, 2002, 80[24], 4537-9