Improved electrical properties of tin-oxide films by using ultralow-pressure sputtering process

The improved structural and electrical properties of tin-oxide films produced by using ultralow-pressure sputtering (ULPS) method are reported. The Hall mobility of the film (~ 13 cm2/V s) deposited using ULPS was about 1.5 times higher than that of the film (~ 8 cm2/V s) sputtered using a pressure of 4.0 × 10− 1 Pa. As the sputtering pressure was decreased, the film was transformed from an amorphous structure to a nano-crystalline one and gained a stoichiometric SnO2 composition. These changes in the film structure sufficiently decreased the carrier concentration to facilitate application to thin film transistors.