By developing a low-temperature (≤300°C) fabrication process for the gate-stack structure on Ge(111), we study electrical properties of thin film transistors (TFTs) consisting of (111)-oriented pseudo-single-crystalline-germanium (PSC-Ge) channels on glass. Although the Hall mobility (μ Hall) of p-type PSC-Ge layers reaches 210cm2/Vs and the gate-stack/Ge interface has low trap density, we observe field-effect-mobility (μFE) fluctuation in the p-channel TFTs from 8.2 to 71cm2/Vs, depending on the thickness of the PSC-Ge layer. Considering the μFE fluctuation and low I on / I off ratio in the p-TFTs, we infer the presence of defective Ge layers near the surface of the glass substrate. This study reveals that it is quite important for the high-performance p-Ge TFTs to improve the quality of the Ge layer near the surface of the glass substrate or to choose other materials with better Ge/substrate interface qualities.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)