Photon-induced modifications in cadmium telluride/mercury cadmium telluride heterostructure interfaces

We report on photon-induced modifications in CdTe/MCT (cadmium telluride/me rcury cadmium telluride) heterostructure interfaces formed by flash evapora ted CdTe on to the bulk p-Hg0.8Cd0.2Te. Metal-insulator-semiconductor (MIS) test structures were processed and their electrical properties measured by capacitance-voltage (C-V) and current-voltage characteristics. The effect of preannealing the MCT wafers under photon excitation and in Hg environmen t as well as the postannealing of CdTe/MCT under photon excitation were inv estigated. By optimizing the preanneal and postanneal processes, a signific ant improvement in the interface characteristics was obtained as evidenced by C-V measurements. The ultraviolet (UV) photons seem to play an important role in the process. The Hg atoms in the vapor phase absorb UV photons. In the presence of excited Hg atoms, hydrogen radicals are formed by direct c ollisions in the vapor phase and passivate the MCT surface. (C) 2000 Americ an Institute of Physics. [S0003-6951(00)03935-8].