Electronic band Gap of ZnO under triaxial strain

The effect of triaxial strains on the band gap of wurtzite ZnO has been investigated by the first principles calculations. The results indicate that, after application of triaxial strain, the wurtzite ZnO is still a direct band gap semiconductor with conduction- and valence-band minima remains at the Γ point. Comparing with the unstrained ZnO, the Eg at Γ point increases under compressive strain but decreases under tensile strain. This triaxial strain model is in better agreement with the experimental results than the widely-employed in-plane biaxial strain model, thus providing a more accurate explanation on the behaviors of ZnO thin film under three-dimensional strain.