Interface Dipole and Schottky Barrier Formation at Au/CdZnTe(111)A Interfaces

Synchrotron radiation photoemission spectroscopy (SRPES) has been used to study the electronic structure of the Au/CdZnTe(111)A for Au coverage ranging from about 0.3 up to 20 monolayers (ML). It is found that a Schottky barrier with a height of 0.82 eV is formed at the initial deposition of Au. This barrier decreases gradually with increasing Au coverage, which can be ascribed to band bending caused by charge redistribution at the interface and the formation of a positive interface dipole introduced by Cd diffusion. After an annealing process, a signal due to the formation of Au-Cd alloy caused by exquisite Cd diffusion into Au overlayer is observed, and simultaneously the Schottky barrier height (SBH) reduces to 0.32 eV. The present work indicates that cation diffusion into metal overlayer plays a critical role in controlling the SBH.