Effects of oxygen partial pressure on the microstructure, electrical and optical properties of the Sn-doped In2O3 thin films

Abstract

The effects of oxygen partial pressure on the microstructure, electrical and photo-sensitive properties of the Sn-doped In2O3 (ITO) films deposited by different Ar–O2 flow rates (10:0.4, 10:1, 10:1.8 and 10:3) were investigated systematically by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Hall effect, UV-Vis and optical measurements. The XRD and SEM measurements show that the ITO film deposited at oxygen flow rate of 0.4 sccm prefers to (400) orientation and has a rough sawtooth-shaped surface. However, the ITO films deposited at oxygen flow rates of 1 sccm, 1.8 sccm and 3 sccm prefer to (222) orientation and exhibit a flat smooth surface. The conductivity, mobility and photosensitive property of ITO films are also sensitive to oxygen flow rate. The ITO film deposited at oxygen flow rate of 0.4 sccm has a high carrier concentration (up to [Formula: see text] cm[Formula: see text]) and mobility (16.7 cm2/vs), low resistivity [Formula: see text], and a long response time but good sensitivity to ultraviolet light. It can be concluded that the surface morphology plays a dominant role in sensitivity to ultraviolet light. The good sensitivity of ultraviolet light is gained from the ITO film with sawtooth-shaped surface.