Characterization of nanocrystalline indium tin oxide thin films prepared by ion beam sputter deposition method

Abstract

Indium tin oxide (ITO) thin films were deposited on glass substrates by ion beam sputter deposition method in three different deposition conditions [(i) oxygen (O 2) flow rate varied from 0.05 to 0.20 sccm at a fixed argon (1.65 sccm) flow rate, (ii) Ar flow rate changed from 1.00 to 1.65 sccm at a fixed O 2 (0.05 sccm) flow rate, and (iii) the variable parameter was the deposition time at fixed Ar (1.65 sccm) and O 2 (0.05 sccm) flow rates]. (i) The X-ray diffraction (XRD) patterns show that the ITO films have a preferred orientation along (400) plane; the orientation of ITO film changes from (400) to (222) direction as the O 2 flow rate is increased from 0.05 to 0.20 sccm. The optical transmittance in the visible region increases with increasing O 2 flow rate. The sheet resistance (R s) of ITO films also increases with increasing O 2 flow rate; it is attributed to the decrease of oxygen vacancies in the ITO film. (ii) The XRD patterns show that the ITO film has a strong preferred orientation along (222) direction. The optical transmittance in the visible spectral region increases with an increase in Ar flow rate. The R s of ITO films increases with increasing Ar flow rate; it is attributed to the decrease of grain size in the films. (iii) A change in the preferred orientations of ITO films from (400) to (222) was observed with increasing film thickness from 314 to 661 nm. The optical transmittance in the visible spectral region increases after annealing at 200 °C. The R s of ITO film decreases with the increase of film thickness.