A study on photoluminescence of interface layer of ZnTe/CdTe heterostructure

By e-beam evaporation, the passivant ZnTe has been deposited onto the CdTe surface that is treated by suitable etching solution to prepare a better su rface condition for the deposition. The structural variations and the optic al properties of the interface layer of ZnTe:CdTe heterostructure according to the condition of pre-heating and thermal annealing have been studied by photoluminescence (PL) and X-ray diffraction (XRD) measurements. The PL re sult reveals that the deep-level donor acceptor pair (DAP) emission related to the concentration of acceptor centers (isolated cadmium vacancies: V-Cd ) responsible for interface trap states (Te4+) is reduced by thermal anneal ing. From XRD results, it is shown that the polycrystal layer of ZnTe is tr ansformed to the polycrystal layer of CdZnTe by the thermal annealing proce ss. By Auger electron spectroscopy (AES), the relative composition and the interface structure of ZnTe/CdTe after thermal annealing are analyzed. It i s indicated that the CdZnTe layer is formed by interdiffusion process throu gh the interface of ZnTe/CdTe. (C) 2000 Elsevier Science B.V. All rights re served.