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 V of pure In2O3 TFT to −1~1 V 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 V, compared to much higher ΔVon of −7.9~−15.6 V 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.
Highlights
Amorphous oxide semiconductors are promising for their use in thin-film transistor (TFT) devices due to their high carrier mobility and large-area uniformity
Comprehensive studies reveal that different lanthanides (Lns) have a different effect on the negative bias illumination stress (NBIS) stability of Amorphous oxide semiconductors (AOSs) TFTs, and Pr/Tb acts a Vo suppressant and a blue light downconversion medium with low charge transfer transition energy
Von of −13.3 V, the lanthanide-doped indium oxide (Ln):In2O3 TFTs have more positive Von that range from −1 to 1 V and steeper SS, revealing that Ln doping with a concentration of only 5 at.% can suppress
Summary
Amorphous oxide semiconductors are promising for their use in thin-film transistor (TFT) devices due to their high carrier mobility and large-area uniformity Their commercialization is limited by the negative gate bias stress experienced under continuous light illumination. Hosono et al.[22] developed a wide-bandgap AOS (ZnGaO) to improve the NBIS stability of the AOS TFTs by widening the optical bandgap to keep the photoexcitation energy between the subgap states and the conduction band minimum (CBM) larger than ∼3 eV This approach will decrease the mobility seriously, because the 4 s orbitals of adjacent metal ions (both Ga and Zn) do not overlap that would destroy the electron transport paths in the amorphous state. It is should be noted that promethium (Pm) is not included in this work because of its radioactivity
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