NOVEL METHOD FOR GROWING CDS ON CDTE SURFACES FOR PASSIVATION OF SURFACE-STATES AND HETEROJUNCTION FORMATION

Large-grain polycrystalline CdTe was subjected to in situ H2S plasma p rocessing for <30 min at 100 and 200 degrees C. High-resolution x-ray photoemission measurements on the Cd 4d, Te 4d, and S 2p core levels, and the valence band were used to determine the resultant chemical env ironment of S and the electronic structure at the CdTe surface followi ng plasma processing. Auger electron spectroscopy compositional depth profiling was also used to determine the distribution of S in the near surface region. Furthermore, time-resolved photoluminescence was used to measure carrier lifetimes and, thus, determine the degree of passi vation of CdTe surface states. These results provide evidence for a Cd S/CdS1-xTex/CdTe heterojunction device structure, as a result of the H 2S plasma processing, and a reduction in the surface recombination vel ocity through passivation of surface states. This is a novel method of fabricating CdS/CdTe heterojunction devices. (C) 1997 American Vacuum Society.