High-Mobility Thin-Film Transistors Based on InZnGeO Channel Layer

Abstract

In this work, the etch-stopper layer (ESL) structured InZnGeO thin-film transistors (TFTs) were prepared. Here, doping Ge has a high Hall mobility and helps to achieve high mobility, which compares to the mobility of InGaZnO TFT. We investigated the influence of SiO2 ESL deposition temperature on the performance of InZnGeO TFTs. As the ESL deposition temperature increased, the mobility of InZnGeO TFT went up from 23.6 to 41.3 cm2 V-1 s-1 and the current ratio ( ${I}_{\text {on}}$ / ${I}_{\text {off}}$ ) increased from $1.2\times 10^{{7}}$ to $4.3\times 10^{{8}}$ . X-ray photoelectron spectroscopy showed that low-temperature deposited ESL has a large amount of hydrogen bonding. The impact of ESL deposition temperature on the distribution of subgap states in InZnGeO thin films is qualitatively analyzed by the Silvaco Atlas 2-D simulator, which reveals that shallow-level subgap defect states can be suppressed by decreasing oxygen-related defects. The results confirmed that Ge doping may be a prospective method for improving the mobility of TFTs with ESL deposited at a high temperature.