thin-film transistors (TFTs) are fabricated using as gate dielectrics. The enhancement of the electric characteristics is observed after a postannealing processing including the reduction of the threshold voltage , the increase in mobility , and the on/off ratio. The effect of the postannealing temperature on both the interfacial bonding structure and the crystallinity is investigated. We suggest that the interfacial modification at the interface contributes to the significant reduction of due to the breaking of Si–O–Ti bonding. The improvement of the crystallinity and interfacial structure leads to the increase in and in the on/off ratio. The low-temperature annealing treatment at 200 is very effective to improve the interface structure.