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Surface morphology and depth profile study of Cd1-xZnxTe alloy nanostructures

Yilmaz, Ercan
Tugay, Evrin
Aktag, Aliekber
Yıldız, İlker
Parlak, Mehmet
Turan, Raşit
Cd1-xZnxTe thin films with thickness of 200 nm were deposited on glass substrates from a single sputtering target. During the deposition process, the substrates were heated at 400 degrees C and deposited films were subjected to an annealing process at 300 and 450 degrees C for an hour under flowing N-2 gas at atmospheric pressure. Influence of in situ heating and post-deposition annealing treatments on the structural and optical evolution of Cd1-xZnxTe nanostructures were investigated by diagnostic techniques such as X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS), and UV-transmission spectroscopy. The transmission spectra in the region of the optical absorption band edge were measured for as-deposited and heat-treated of CdZnTe samples. Band gap of the deposited films were found to be in the range of 1.59-1.66 eV. The XRD studies revealed that heated Cd1-xZnxTe films have a cubic oriented (111), (220) and (311) polycrystalline structure whereas unheated films are mostly amorphous. The effects of annealing temperature on the composition of the thin films were discussed. XPS measurements were performed in the depth profiling mode in order to understand the variation in the chemical composition of the films. Results were compared with the structural analysis obtained from the XRD measurements. (C) 2012 Elsevier B.V. All rights reserved.