Temperature Properties of Amorphous In-Ga-Zn-O Thin-Film Transistors with a new Mobility Model

1. Introduction

Amorphous In-Ga-Zn-O (a-IGZO), which is a typical amorphous oxide conductor (AOS), is considered to be one of the most promising channel materials of thin-film transistors (TFTs) for new flat-panel displays because of the high mobility, the small sub-threshold swing and the low off current [1].

When devices with a-IGZO TFTs are developed, it is necessary to consider operation of the TFTs under various bias and temperature conditions. In many cases, it has been understood as the operation of the a-IGZO TFT is similar to that of a-Si TFT and dominated by the density of sub-gap states (DOS) with a fixed band mobility [2]. However, it is difficult to reproduce the operation because the DOS of the a-IGZO TFT near conduction band is much lower, about two orders, than that of the a-Si TFT.

In this paper, we introduce a new mobility model, “IGZO.TOKYO,” which can reproduce temperature properties of the a-IGZO TFT [3]. Additionally, methods to extract the model parameters and DOS from the transfer curve are also shown so as to use the model easily.