Effects of film thickness and sputtering power on properties of ITO thin films deposited by RF magnetron sputtering without oxygen
In this work, indium tin oxide (ITO) thin films were grown on a glass substrate without introducing oxygen into the growth environment using RF magnetron sputtering technique. The dependence of surface morphological, optical and electrical properties at different film thicknesses and sputtering RF power were investigated. Results showed that these properties were strongly influenced by the film thickness and sputtering RF power. It was found that the resistivity, sheet resistance and optical transmittance of ITO thin films deposited on glass substrate decreased as film thickness increased from 75 to 225 nm while the surface roughness and optical bandgap increased. The optimum properties were obtained for ITO films 225 nm thick grown at 250 W RF power. This has revealed an excellent figure of merit of (38.4 × 10−4 Ω−1) with average transmittance (83.3 %), resistivity (9.4 × 10−4 Ω cm), and carrier concentration (6.1 × 1020 cm−3). These ITO films are suitable for use in solar cells applications.
KeywordsFilm Thickness Carrier Concentration Sheet Resistance Optical Transmittance Spectrum High Optical Transmission
The authors would like to thank Gary Turner and Helen Devereux from the Nanofabrication Laboratory, University of Canterbury, New Zealand for providing technical assistance and Prof. Roger Reeves for transmittance measurements. Amalraj PA acknowledges the UC Doctorate Scholarship, University of Canterbury, New Zealand.