First-Principles Studies of Metal (111)/ZnO{0001} Interfaces

The atomic and electronic structures for various metal (111)/ZnO{111} interfaces were studied by first-principles calculations based on density functional theory. The Schottky barrier heights (SBHs) were evaluated for Al, Ag, and Au/ZnO interfaces. SBHs at metal/ZnO polar interfaces were found to be very sensitive to the specific interface chemical bonding. Interface metal-zinc bonding tends to give Ohmic contacts, while the contribution of metal-oxygen bonds depends on the specific metal: simple metals gives Ohmic contacts whereas noble metals gives Schottky-like behavior. We discussed the implications of these results for controlling the formation of metal/ZnO contacts.