High-performance InGaZnO thin-film transistors with high-k amorphous Ba0.5Sr0.5TiO3 gate insulator

Abstract

We report on high-performance n-channel thin-film transistors (TFTs) fabricated using amorphous indium gallium zinc oxide (a-IGZO) and amorphous Ba0.5Sr0.5TiO3 (a-BST) as the channel and gate dielectric layers, respectively. a-BST∕a-IGZO TFTs achieve low-voltage operation with a high saturation mobility value of 10±1cm2∕Vs, excellent subthreshold slopes of 0.06±0.01V/decade, a low threshold voltage of 0.5±0.1V, and a high on-off current ratio up to 8×107 (W∕L=1000μm∕5μm) at 3V. The high capacitance density of a-BST (145±2nF∕cm2) and the small contact resistance, smaller than the channel resistance, are responsible for the high performance of these TFTs.