Studying Effect of Frequency on Capacitance–Resistance of Al/ITO/Al Humidity Sensor Prepared by Pulsed Laser Deposition

Abstract

Indium tin oxide (ITO) nanostructured films were deposited onto glass substrates using pulsed-laser deposition. The structure, shape, and optical properties of the deposited films were characterized. The ITO films were found to be polycrystalline with preferred at (222) crystal orientation (2θ=30.65°), and average crystallite size of about 23.22 nm when annealed at 200 °C for 60 minutes. The films exhibited an optical band gap around 3.4 eV due to the nanostructure formation and deposition method. The films showed uniform morphology with minimum surface roughness. They were also assessed for humidity sensing devices through capacitive-resistive method at the lower frequencies (100, 200, and 300 Hz) at room temperature. The results indicated that both resistance and capacitance were reduced with increasing frequency showing the possibility to employ the prepared films as efficient humidity sensor.