Structural and electronic properties of the Te-rich ZnOxTe1-x

The structural and electronic properties of the Te-rich ZnOxTe1-x are calculated via first-principles calculations. It is found that the lattice constant exhibits a decreasing trend and it has a negative bowing coefficient. The bandgap narrowing in the Te-rich range is by reason of the introduction of the O level in the bandgap, the downward movement of the conduction band minimum (CBM) and the upward movement of the valence band maximum (VBM). The band crossing is due to that the bottom of the Zn-4 s states in the conduction band is lowered after more O atoms are bonded with Zn atoms. In order to solve the problem of the description for the CBM due to the band crossing in the Te-rich range, the energy which the initial lowered Zn-4 s states correspond to in the modified band anticrossing (BAC) model choose the same value with that of the initial O level which the O-2 s states introduce. Additionally, the combination of the modified BAC model and the standard bowing equation is proposed to describe the bandgap energy in the Te-rich range. It is found that the model in this work can give a good description.