Effect of Dopant Concentrations on Sensing Properties of Ni Doped TiO 2 based Resistive Humidity Sensor

Abstract In the present work, effect of different volume percentages ( vol % ) of Ni doped TiO 2 thin films on structural, microstructural, electrical, optical and humidity sensing properties were investigated. The pristine TiO 2 and Ni doped TiO 2 thin films were synthesized for different vol% of Ni dopants such as 1 vol% , 2 vol% and 4 vol%. onto the glass substrate using spray pyrolysis technique. Structural properties of synthesized sample showed polycrystalline anatase tetragonal phase with dominant (101) peak. Electrical resistance of the samples also decreased with increase in dopant concentration. Temperature coefficient of resistance and activation energy shows strong correlation with dopant concentration. The optical band gap of the samples also decreased with rise in Ni dopant vol% up to 2, but further rise in concentration it increased for 4 vol% . The maximum humidity sensitivity of 89% was observed for the sample with 2 vol% of Ni doped TiO2 with low response time of 64 s.