Electrical and optical properties of amorphous (In, Sn)-Ga-Zn-O thin film

Films of amorphous In _1-xSn _xGaZnO _δ (a-ISGZO) (x = 0.0∼1.0) were pulsed laser deposited at a temperature range of room temperature to 300 °C, and in order to systematically investigate the effect of replacing In with Sn on the properties of amorphous In-Ga-Zn-O (a-IGZO), the electrical and optical properties were measured. The amount of Sn in the deposited film, which was determined by X-ray photoelectron spectroscopy, was very close to the composition of the targets used. Hall mobility and carrier concentration decreased, and resistivity increased as the amount of Sn in the film increased. It was observed that the increase of Sn concentration in films was accompanied by the decrease of oxygen vacancy concentration, which led to the decrease of carrier concentration. The electrical mobility was decreased as the amount of Sn increased, which can be attributed to the increased number of subgap states, which was determined by the UV/VIS spectrophotometer. Optical transparencies of all samples were larger than 80% in the visible light range. Band gap values were also found to increase as the amount of Sn increased.