Cr2O3:TiO2 Nanostructure Thin Film Prepared by Pulsed Laser Deposition Technique as NO2 Gas Sensor

Abstract

Pulsed laser deposition (PLD) technique was applied to prepared Chromium oxide (Cr₂O₃) nanostructure doped with Titanium oxide (TiO₂) thin films at different concentration ratios 3,5,7 and 9 wt % of TiO₂. The effect of TiO₂ dopant on the average size of crystallite of the synthesized nanostructures was examined by X-ray diffraction. The morphological properties were discussed using atomic force microscopy(AFM). Observed optical band gap value ranged from 2.68 eV to 2.55 eV by ultraviolet visible(UV-Vis.) absorption spectroscopy with longer wave length shifted  in comparison with that of the bulk Cr₂O₃ ~3eV. This indicated that the synthesized samples are attributed to the enhancement of the quantum confinement effect. Gas response sensitivity, and recovery times of the sensor in the presence of NO₂ gas were studied and discussed. In this work it is found that, the sensitivity increases when doping ratio increases from 3wt% to 5wt% of TiO₂  and return to decrease over that. The optimum concentrations ratio for NO₂ gas sensitivity is 5wt% of TiO₂  and sensitivity is 168.75% at 200^oC.