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

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 SiO
$_{\text{2}}$
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 cm
$^{\text{2}}$
V
$^{\text{$
-
$1}}$
s
$^{\text{$
-
$1}}$
and the current ratio (
$\textit{I}_{\text{on}}$
/
$\textit{I}_{\text{off}}$
) increased from 1.2
$\times$
10
$^{\text{7}}$
to 4.3
$\times$
10
$^{\text{8}}$
. 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.