Effects of O2/Ar ratio and UV illumination on the properties of radio frequency sputtered TeOx thin films

Tellurium oxide (TeOx) thin films have been prepared by rf reactively sputtering deposition by using a tellurium target under Ar-O2 gas mixture. The effect of O2/Ar ratio on the structure and optical properties was investigated by XRD, FTIR and optical transmission measurement. With increasing the O2/Ar ratio the optical band gap of thin films increased from 0.59eV to 0.87eV, but the Urbach energy firstly decreased, then increased. After UV illumination, the blue and red shifts of absorption edge were observed. And the annealing of as-deposited films also was done. It was proposed that the blue and red shifts may be related with the Urbach energy. All the results can be attributed to the rearrangement of bonding network with the variation of stoichiometry of tellurium oxide films.

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