Preparation and characterization of pure and doped v2o5 thin films for toxic gas sensing application

Abstract

The title of the present thesis is Preparation and characterization of pure and doped V2O5 thin films for toxic gas sensing application . Pure and molybdenum doped V2O5 thin films deposited on a glass substrate using a low-cost spray pyrolysis technique. Initially, pure V2O5 thin films are deposited with optimized deposition parameters by varying substrate temperatures in the range of 275°C-350°C. The effect of substrate temperature on micro-structural, morphological and optical properties are investigated. The film which was deposited at a substrate temperature of 325 °C has shown high degree of crystallinity and optical transmittance with Gossamer morphology. Hence this substrate temperature of 325°C is optimized for further discussion. The effect of precursor concentration in the range of 0.025M, 0.050M, 0.075M, and 0.1M on micro-structural, optical and morphological properties. At the low concentration of the precursor, films showed amorphous nature, 0.075M the films are polycrystalline with the orientation along (110) plane. From Raman analysis, the vibration at 143 cmand#8722;1 and the stretching vibration at 995 cmand#8722;1 is the evidence for the impeccable layer-type structure of V2O5 thin films at the concentration of 0.075M. It has suggested that 0.075M concentration is optimal for attaining device quality films. To investigate effect of annealing temperature on structural, morphological and optical properties, the samples which was deposited at a substrate temperature of 300°C was annealed at different temperatures such as 350°C, 400°C and 450°C. It was observed that there was no significant impact of annealing temperature on the structural, morphological and optical properties in comparing with the other cases. Later on, molybdenum doped V2O5 thin films with different mole percentage (1mole %, 3mole % and 5mole %) were deposited on microscopic glass substrates using a low cost spray pyrolysis technique with optimized deposition parameters. The films which deposited with a concentration newline