Modification of intrinsic defects in IZO/IGZO thin films for reliable bilayer thin film transistors

Abstract

Dual active channel IZO/IGZO thin film transistors as such and with ZnO interlayer are fabricated and characterized to investigate the impact of ultra-thin ZnO insertion on their performance and bias stability. The ZnO interlayer suppresses the pre-existing divalent zinc vacancies and oxygen vacancies in the IZO front layer as systematically investigated by photoluminescence and XPS analysis. This interlayer leads to an enhancement of the electrical characteristics and stability of the bilayer TFT in comparison to the counterpart TFTs fabricated by a single IZO and a-IGZO-channel device. A high-field effect mobility (∼14 cm² V⁻¹ s⁻¹) IZO/IGZO transistor with excellent photo-bias stability (ΔV_th ∼ −2.45 V) was obtained from 2 nm ZnO insertion in between the IZO and IGZO layer-enabling backplane electronics for high-resolution and large-sized AMOLED and TFT-LCD displays.