ITO films deposited on water-cooled flexible substrate by bias RF Magnetron Sputtering

Indium tin oxide (ITO) films were deposited on water-cooled polypropylene adipate (PPA) substrate using bias RF magnetron sputtering from a ceramic target composed of In2O3, (90%) + SnO2 (10%). Good polycrystalline-structured ITO films with a low electrical resistivity of 6.3 X 10(-4) Ohm cm have been obtained by applying a negative bias of about -40 V to the substrate at a water-cooled substrate temperature(18 +/- 2 degrees C). The visible transmittance of all obtained films was over 80% and in the wavelength range of 400-550 nm, the transmittances increase with increasing the negative bias. X-ray diffraction spectra revealed that all the films oriented preferably with [222] direction and [400] diffraction peak decreased with increasing the negative bias. Both the X-ray diffraction spectra and atomic force microscope (AFM) measurement suggested that the average crystalline size, as well as the conductivity have a maximum value at the bias of about -40 V. The influences of argon pressure and the proportion of SnO2, on the conductivity of the films were also studied. The optimum argon pressure is 0.5-1 Pa, and the proper content of SnO2, is 7.5-10 wt.%. (C) 2000 Elsevier Science B.V. All rights reserved.