Schottky barrier height at metal/ZnO interface: A first-principles study

The Schottky barrier heights (SBHs) of various metals on ZnO are investigated by first-principles calculation. The SBHs decrease linearly with increasing metal work function, which follows the prediction of the metal-induced gap states (MIGS) model. The pinning factor S is calculated to be 0.56 which indicates moderate pinning effect. A closer look at the interfacial electronic structure shows the dominant rule of oxygen in forming the MIGS. To extend the concept of MIGS model to the band alignment between semiconductors, a calculation is performed on Si/ZnO interface. Si is found to have a type-II band alignment with ZnO, the conduction band offset (CBO) and valence band offset (VBO) are calculated to be 0.5 eV and 2.5 eV respectively. The results agree with the experimental values and the predicted values based on the charge neutrality level (CNL) method