Journal of Vacuum Science & Technology A, Vol.12, No.5, 2803-2807, 1994
Processing and Characterization of Large-Grain Thin-Film CdTe
Basic material studies addressing the growth and processing of CdTe have resulted in dense, defect-free as-grown CdTe films on 7059 glass with initial grain sizes of almost-equal-to0.2 mum. Innovations in postdeposition processing (no CdCl2) have resulted in films with >50 mum grain sizes. Scanning electron microscopy analyses confirm film density while concurrent cathodluminescence reveals a change in the recombination efficiency. Transmission electron microscopy analyses reveal that films grown below 300-degrees-C are defect-free, while films grown above 300-degrees-C contain defects. Photoluminescence lifetime measurements reveal a fivefold increase in lifetime following posdeposition processing of these films. These results were correlated with x-ray photoemission measurements of the Te 4d, Cd, 4d, and valence band. This indicates that grain boundaries are the main factor limiting lifetimes. Based on these results, we have developed an understanding of the effects of oxygen and grain boundary oxides on postdeposition processing and enhanced grain growth.