Properties of Resistivity, Reflection and Absorption Related to Structure of ITO Films

Indium tin oxide (ITO) films were fabricated on polyethylene terephthalate (PET) substrate at room temperature using dc magnetron sputtering technique with different sputtering powers. The structural, electrical and optical properties were investigated by X-ray diffraction (XRD), Hall effect, reflection and transmission, respectively XRD patterns show gradual enhancement of crystalline quality with increasing sputtering power. Significant improvement of Hall mobility due to the reduction of defects was observed though the carrier density varied slightly. Simultaneously, the mean transmission in visible light range decreased severely with increasing sputtering power. Slight move toward shorter-wavelength side of absorption peak was due to the variation of plasma wavelength. The reflection increase of near-infrared light originated from the decrease of resistivity. Finally band gap was obtained using Tauc's relation and it was consistent with Burstein-Moss shift.