Nanoindentation of Si, GaP, GaAs and ZnSe single crystals

We present a systematic study of the mechanical properties of bulk Si, GaP, GaAs and ZnSe semiconducting materials. Nanoindentation tests have been performed on the (001) surface of single crystals and their interpretation has been supported by AFM imaging of the indented surface. For all four materials, hardness and Young's modulus appear to be independent of the orientation of the Berkovich nanoindenter tip relative to the [100] direction. In contrast, hardness varies significantly with the applied load for ZnSe, which is the only material exhibiting large creep. All mechanical properties-plasticity, hardness, Young's modulus-depend on both the interatomic distance and the ionicity of the materials. Si and ZnSe are, respectively, the hardest and the softest materials of the series, the hardness of ZnSe being comparable to that of soft metals.