The effect of charge transfer transition on the photostability of lanthanide-doped indium oxide thin-film transistors

Abstract

Amorphous oxide semiconductors are promising for their use in thin-film transistor (TFT) devices due to their high carrier mobility and large-area uniformity. However, their commercialization is limited by the negative gate bias stress experienced under continuous light illumination. Here, we report an approach to improve the negative bias illumination stress (NBIS) stability of amorphous oxide semiconductors TFTs by using lanthanide-doped indium oxide semiconductors as the channel layer. The effect of different lanthanide dopants on performances of solution-processed Ln:In2O3 TFTs are investigated. All lanthanides exhibit strong suppression of oxygen vacancy, which shift the Von from −13.5\u2009V of pure In2O3 TFT to −1~1\u2009V of Ln:In2O3 TFTs (except Ce). However, only Pr:In2O3 and Tb:In2O3 TFTs exhibit much better NBIS stability with same ΔVon of −3.0\u2009V, compared to much higher ΔVon of −7.9~−15.6\u2009V for other Ln:In2O3 TFTs. Our comprehensive study reveals that praseodymium and terbium act as a blue light down-conversion medium with low charge transfer transition energy for lowing photosensitivity of oxide semiconductors. Thin-film transistors based on amorphous oxide semiconductors have promising applications, but their stability is hampered by negative bias illumination stress. Here, a systematic study of lanthanide-doped indium oxide semiconductors reveals that Pr and Tb are most efficient in improving the photostability of devices.