Junctionless low-voltage thin-film transistors based on indium-tin-oxide

Abstract

Bottom-gate junctionless thin-film transistors (TFTs) based on indium-tin-oxide (ITO) are fabricated at room temperature. Source/drain electrodes and channel layer are the same ITO thin films without source/drain junction formation, hence the fabrication process is greatly simplified and the fabrication cost is reduced. We employ electric-double-layer (EDL) SiO2 with large capacitance as the gate dielectric, and find that the drain current can be effectively modulated by the gate bias when the thickness of ITO film decreases to about 20 nm. These junctionless TFTs show excellent electrical performances with a small subthreshold swing of 0.13 V/dec, a high mobility of 21.56 cm2/V·s and a large on/off ratio of 1.3× 106. The performances of these junctionless TFTs do not show significant degradation even after 4 months in air ambient, the subthreshold swing is still 0.13 V/dec, the mobility slightly decreases to 18.99 cm2/V·s and the on/off ratio is still larger than 106. Such TFTs are very promising for the applications in low-cost low-power portable electronic products and novel sensors.