Yielding and plastic slip in ZnO

The mechanical properties of ZnO were examined using nanoindentation and microcompression. The modulus, hardness, onset of yielding, and shear strength of the as-grown wafer measured by nanoindentation are 140, 7.1, 12, and 3.6 GPa. The onset of shearing (3.6 GPa) corresponds to the theoretical shear strength. Young's modulus and yield strength measured from micropillar samples were 123 and 3 GPa. The primary slip plane forms an acute angle of 62° with respect to the basal planes, indicting it is pyramidal. Thermal annealing does not affect the residual stresses but can reduce the defect concentration, thus improves the ZnO luminescent properties.