Interfacial chemistry and the performance of bromine-etched CdZnTe radiation detector devices

The interfacial chemistry and composition of Pt electrodes sputter deposited on bromine-etched CdZnTe surfaces was studied by X-ray photoelectron spectroscopy. The interfacial composition of a functioning and a nonfunctioning CdZnTe detector shows significant differences. The degree of cation out-diffusion into the Pt overlayer and the in-diffusion of Pt into the CdZnTe correlate with the degree of oxidation found at the metal-semiconductor interface. Most of the oxide present at the interface was found to be TeO₂. The results suggest that the interdiffusion of the atoms and associated charges contribute to stoichiometric variations at the metal-semiconductor interface and influence the electrical performance of the devices.