Effect of Annealing Temperatures on Optical and Electrical Properties of TiO2/Mo Multilayer Films for Photosensor Applications

In this study, titanium dioxide (TiO2) and molybdenum (Mo) with a purity of 99.99% were deposited on a glass substrate under various parameters through RF magnetron sputtering to form TiO2/Mo bilayer and TiO2/Mo/TiO2 multilayer transparent conductive thin films. In addition, the films were annealed in vacuum at various temperatures to adjust their internal crystallization through thermal energy such that they exhibited replacement characteristics and fewer internal defects. After the bilayer films with a Mo-doped metal layer and the TiO2/Mo/TiO2 multilayer films were annealed, the thickness, electrical properties, optical properties, surface structure, and figure of merit (FOM) of the thin films were examined. The results indicated that the TiO2/Mo bilayer films had a low resistivity of 1.97 x 10(-1) Omega-cm before annealing and an average transmittance rate of 66.59%; the unannealed TiO2/Mo/TiO2 multilayer films had a resistivity of 7.21 x 10(-3) Omega-cm and an average transmittance rate of 69.34%. The optical transmittance of both structures tended to increase with their annealing temperature, and an optimal light transmittance rate of 77% was achieved. For the FOM, the optimal values of the bilayer and multilayer structures were 5.96 x 10(-7) and 4.46 x 10(-5) Omega(-1), respectively. The results indicate that TiO2/Mo/TiO2 thin films are suitable for photosensor applications.