Influence of ion-beam sputtering deposition parameters on highly photosensitive and transparent CdZnO thin films
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CdZnO thin films with a nominal thickness of ~200 nm were grown on c-plane sapphire substrates by dual ion-beam sputtering deposition technique. The effect of substrate temperature (300–600 °C) and gas ambience on structural, morphological, compositional and opto-electronic properties was studied. X-ray diffraction patterns confirmed that all the films were polycrystalline in nature and were preferentially oriented along the c-axis. It was revealed that the films grown at Ar/O2 ratio of 4:1 were structurally more ordered and the film quality was found to be the best at 500 °C. The compositional studies specify that approximately 11.8 at.% of cadmium were present in the film deposited at 300 °C in Ar–O2 mixture. Investigations on optical properties by photoluminescence and absorption studies indicate band gap shrinkage with the increase in argon partial pressure and substrate temperature. It was found that photosensitivity of the deposited films was highly dependent on growth conditions. The photosensitivity was found to be 5000-fold higher for CdZnO film grown at 600 °C in Ar–O2 ambience compared to the best reported result, and this was promising to realize high-performance opto-electronic devices on such CdZnO films.
KeywordsSubstrate Temperature Oxygen Interstitial Deep Level Emission Regular Lattice Site Argon Partial Pressure
This work was partially supported by Department of Science and Technology (DST) Fast Track Scheme for Young Scientist No. SR/FTP/ETA-101/2010, DST Science and Engineering Research Board (SERB) Project No. SR/S3/EECE/0142/2011, and Council of Scientific and Industrial Research (CSIR) Project No. 22(0608)/12/EMR-II. We are also grateful to the AFM Facility equipped at Sophisticated Instrument Centre at IIT Indore and T. Shripathi and U. P. Deshpande, UGC-DAE Indore, for XPS Facility.
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