Significant electrical control of amorphous oxide thin film transistors by an ultrathin Ti surface polarity modifier

Abstract

We demonstrate an enhanced electrical stability through a Ti oxide (TiOx) layer on the amorphous InGaZnO (a-IGZO) back-channel; this layer acts as a surface polarity modifier. Ultrathin Ti deposited on the a-IGZO existed as a TiOx thin film, resulting in oxygen cross-binding with a-IGZO surface. The electrical properties of a-IGZO thin film transistors (TFTs) with TiOx depend on the surface polarity change and electronic band structure evolution. This result indicates that TiOx on the back-channel serves as not only a passivation layer protecting the channel from ambient molecules or process variables but also a control layer of TFT device parameters.