Effect of annealing temperature on TiO ₂-based thin-film-transistor performance

TiO _x thin-film transistors (TFTs) are fabricated using SiO ₂ as gate dielectrics. The enhancement of the electric characteristics is observed after a postannealing processing including the reduction of the threshold voltage V _th, the increase in mobility μ, and the on/off ratio. The effect of the postannealing temperature on both the TiO _xSiO ₂ interfacial bonding structure and the TiO _x crystallinity is investigated. We suggest that the interfacial modification at the TiO _xSiO ₂ interface contributes to the significant reduction of V _th due to the breaking of Si-O-Ti bonding. The improvement of the TiO _x crystallinity and interfacial structure leads to the increase in μ and in the on/off ratio. The low-temperature annealing treatment at 200 °C is very effective to improve the TiO _xSiO ₂ interface structure.