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

Abstract 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 an atmospheric-pressure micro thermal plasma jet ( μ -TPJ). The μ -TPJ-crystallized c-Ge showed a maximum Hall mobility of 1070 cm 2 V −1 s −1 with a hole concentration of ∼10 16 cm −3 , enabling us to fabricate a TFT with a field-effect mobility ( μ FE ) of 196 cm 2 V −1 s −1 and an ON/OFF ratio ( R ON/OFF ) of 1.4 × 10 4 . R ON/OFF and μ FE were dependent on the scanning speed of the TPJ, implying different types of defects were induced in the channel regions. These findings show the possibility of TPJ irradiation as a promising method for making c-Ge TFTs on insulating substrates.