Investigation on electrical characteristics of TFTs fabricated with germanium films crystallized by atmospheric pressure micro-thermal-plasma-jet irradiation

Crystalline-germanium (c-Ge) is an attractive material for a thin-film transistor (TFT) channel because of its high carrier mobility and applicability to a low-temperature process. We present the electrical characteristics of c-Ge crystallized by atmospheric pressure micro-thermal-plasma-jet (µ-TPJ). The µ-TPJ crystalized c-Ge showed the maximum Hall mobility of 1070 cm2·V−1·s−1 with its hole concentration of ~ 1016 cm−3, enabling us to fabricate the TFT with field-effect mobility (μ FE) of 196 cm2·V−1·s−1 and ON/OFF ratio (R ON/OFF) of 1.4 × 104. On the other hand, RON/OFFs and μFEs were dependent on the scanning speed of the TPJ, inferring different types of defects were induced in the channel regions. These findings show not only a possibility of the TPJ irradiation as a promising method to make a c-Ge TFT on insulating substrates.