Noble-metal – CdTe interface formation

The room-temperature Au/p-type CdTe, Ag/n-type CdTe, Cu/n-type CdTe, and Cu/p-type CdTe interfaces have been studied with x-ray and ultraviolet photoelectron spectroscopy for the cleaved CdTe(110) surface. These interfaces are all found to be nonabrupt, with a significant concentration of dissociated Te in the overlayer for all three overlayer metals. The corresponding noble-metal interfaces with Hg_1-x{Cd}ₓ$Te are discussed with respect to these results. The final position of the surface Fermi level ${E}F$ for each interface is ${E}F$-${E}_{VBM=0.95±{}0.1}$ eV for Ag/n-type CdTe, 1.0±{}0.1 eV for Cu/n-type CdTe, 0.9±{}0.1 eV for Cu/p-type CdTe, and 0.8±{}0.1 eV for Au/p-type CdTe. From these results one would expect Schottky barriers between 0.5 and 0.7 eV for these metals on n-type CdTe.