Shallow levels in the band gap of CdTe films deposited on metallic substrates

CdTe thin films were developed on flexible metallic substrates using close spaced sublimation and electrodeposition techniques. The films were nearly stiochiometric, highly uniform and exhibit good crystallinity. The films we re characterized using XRD, SEM and AUGER. The shallow levels in the band g ap of CdTe were determined using photoluminescence and photoinduced current transient spectroscopy. The photoluminescence studies revealed a defect do minated CdTe surface. The two lines detected at 1.587 and 1.589eV at 15 K a re assigned to the donor levels associated with Cl at the Te sites. The add itional features observed in the photoluminescence spectra of the CdCl2 tre ated films revealed that the CdCl2 treatment improves the quality of the fi lms and the close space sublimated films are better than the electrodeposit ed films. The photoinduced current transient spectroscopic technique was ef fectively used to identify the electron and hole traps. Two shallow levels with activation energy 0.056 and 0.13 eV were detected and assigned to elec tron and hole traps, respectively. (C) 2001 Elsevier Science BN. All rights reserved.