Effect of Fluorine doping on H2S gas sensing properties of Zinc Oxide thin films deposited by Spray CVD Technique

Structural, morphological and topographical properties of fluorine-doped ZnO nanostructure semiconductor thin films have been investigated by novel spray CVD technique. The properties of these thin films are governed by the additives of Ammonium Fluoride in non-aqueous solution of Zinc Acetate as a starting material. The crystalline structure and orientation of ZnO thin films have been investigated by X- ray diffraction (XRD) technique for varying Fluorine doping concentration in the range of 0.2 at% to 1 at% in steps of 0.2. The grain size for the films was found to be in the range of 19?23nm. Synthesis of Fluorine doping inducing transition of surface morphology is helpful in studying crystallite size, structure and phase formation by X ray diffraction pattern. For both ZnO and F: ZnO films, the dominant diffraction peak is the (002) peak at around 34.40 , confirming the strong (002) texture of these films. The surface morphology investigated by FESEM was very smooth, more compact, dense with uniform spherical grains supporting the (002) intensity maxima. The H2S gas sensing properties of the films were investigated by using homemade gas sensing unit. The dependence of H2S gas detection on the doping concentration of Fluorine doped Zinc oxide film was studied at 3000C. It is observed that response time and recovery time increases with increase in doping concentration. It is further seen that deteriorated crystallinity and surface morphology with increase in doping concentration improve the gas detection properties of Flourine doped Zinc oxide thin film.