Effect of 80 MeV oxygen ion beam irradiation on the properties of CdTe thin films
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Polycrystalline CdTe thin films were irradiated with 80 MeV oxygen (O6+) ions for various fluences and its effect on the composition, structure, surface topography and optical properties have been investigated. The as-grown films are found to be slightly Te-rich in composition and there is no significant change in the composition after irradiation. X-ray diffraction analysis shows a high degree of crystallite orientation along the (111) plane of cubic phase CdTe. Upon irradiation a large decrease in intensity of the (111) plane and a small shift in the peak position has been resulted. The shift in the peak position is correlated with the change in the residual stress. The surface roughness of the films get increased after irradiation. A decrease in the grain size was observed after irradiation due to ion-induced recrystallization. The optical band gap energy decreased from 1.53 eV for as-grown film to 1.46 eV upon irradiation. The photoluminescence (PL) spectrum is dominated by the defect band and the effect of irradiation has been discussed and correlated with the observed change in the XRD peak position and optical band gap.
KeywordsResidual Stress CdTe Film Defect Band Phonon Replica Irradiate Film
This work was supported by the Inter University Accelerator Centre (IUAC), New Delhi, India through the Project UFUP 34319. The authors cordially acknowledge the help extended by technical staff of Pelletron group during the irradiation experiment. The authors wish to acknowledge Mr. Ambuj Tripathi, Scientist, Inter University Accelerator Centre, New Delhi for his support to carryout the AFM measurements and Dr. D. M. Phase, Scientist and Mr. Vinay Ahire, Junior engineer, UGC-DAE Consortium for Scientific Research, Indore Centre for EDA analysis. One of the authors (RS) gratefully acknowledges University Grants Commission (UGC), New Delhi for awarding UGC-Research Award [Project No. F-30-1/2004 (SA-II)].
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