Effect of Annealing Temperature on TiO2-Based Thin-Film-Transistor Performance

TiOx thin-film transistors (TFTs) are fabricated using SiO2 as gate dielectrics. The enhancement of the electric characteristics is observed after a postannealing processing including the reduction of the threshold voltage Vth, the increase in mobility mu, and the on/off ratio. The effect of the postannealing temperature on both the TiOx/SiO2 interfacial bonding structure and the TiOx crystallinity is investigated. We suggest that the interfacial modification at the TiOx/SiO2 interface contributes to the significant reduction of Vth due to the breaking of Si-O-Ti bonding. The improvement of the TiOx crystallinity and interfacial structure leads to the increase in mu and in the on/off ratio. The low-temperature annealing treatment at 200 degrees C is very effective to improve the TiOx/SiO2 interface structure.