High-performance bilayer IGZO thin-film transistors by sputtering heterojunction with differences in indium elemental content

Abstract The high-quality semiconductor InGaZnO (IGZO) alloy thin films with different indium (In) elemental contents were deposit utilized magnetron sputtering. The novel bilayer heterojunction TFT devices based on our fabricated IGZO films were proposed, and their performance exhibited significant improvement compared to single layer IGZO TFTs. In the bilayer heterojunction TFT, the field-effect mobility was promoted to 23.5 cm 2 ⋅V −1 ⋅s −1 , the switching ratio reached 4.1 × 10 7 , and the subthreshold swing was reduced to 0.42 V/dec. Moreover, the variation of bilayer TFTs threshold voltage ( V th ) was significantly suppressed, Under positive gate bias stress (PBS) and negative gate bias stress (NBS), the threshold shift is reduced to be 1.5 V and −1.1 V, respectively. The heterojunction within the bilayer IGZO films constructs a potential barrier at the interface, which facilitated the accumulation of channel electrons. Additionally, the low In-element content passivation layer in IGZO films not only preserved the channel of TFT but also reduced electron scattering, thereby the performance properties of TFT were enhancing. The excellent transistor characteristics of devices demonstrate the feasibility of our proposed bilayer heterojunction TFT, which will promote the basic research of IGZO device and accelerate the practical application of transparency IGZO TFT.