Study on the physical properties of indium tin oxide thin films deposited by microwave-assisted spray pyrolysis

Abstract

Transparent and conductive indium tin oxide (ITO) thin films were successfully deposited on quartz substrates by the microwave assisted spray pyrolysis method. Microwave heating favors the pyrolysis process to prepare high quality films due to the novel conditions of internal, fast and uniform heating. The effects of microwave pyrolysis temperatures (300–700 °C) on crystal structure, morphology, optical and electrical properties were investigated. X-ray diffraction results confirmed the formation of pure and tetragonal poly-crystalline phase for all the deposited films whose predominant orientation of growth along (222) or (400) direction at different temperatures. By optimizing microwave pyrolysis temperature at 500 °C, scanning electron microscopy and atomic force microscopy results displayed the formation of 318 nm thick film composed of nanograins with narrow sizes distribution and low roughness. The as-deposited ITO thin films showed higher optical and electrical properties, which the average optical transmittance was 86.4% (including 90.1% of the bare substrate) in the visible region, and the sheet resistance and resistivity were 11.11 Ω/□ and 3.54 × 10−4 Ω cm, respectively. The band gaps were determined in the range of 3.78–3.91 eV. Moreover, Haacke's figure of merit reached a maximum value of 33.73 × 10−3 Ω−1 for the ITO film deposited at 500 °C.