Temperature Dependence of Transistor Characteristics and Electronic Structure for Amorphous In--Ga--Zn-Oxide Thin Film Transistor

We fabricated an inverted-staggered amorphous In--Ga--Zn-oxide (a-IGZO) thin film transistor (TFT) and measured the temperature dependence of its characteristics. A threshold voltage ($V_{\text{th}}$) shift between 120 and 180 \mbox{ \circ C} was as large as 4 V. In an analysis with two-dimensional (2D) numerical simulation, we reproduced the measured result by assuming two types of donor-like states as carrier generation sources. Furthermore, by ab initio molecular dynamics (MD) simulation, we determined the electronic structures of three types of a-IGZO structures, namely, "stoichiometric a-IGZO", "oxygen deficiency", and "hydrogen doping".