Fabrication of p-Type SnO Thin-Film Transistors by Sputtering with Practical Metal Electrodes

Abstract

P-type thin-film transistors using polycrystalline tin monoxide (SnO) active layers were achieved by an industry-compatible sputtering technique with a SnO ceramic target. The SnO films clearly exhibited p-type conduction with the p-type Hall mobilities of 1–4 cm2 V-1 s-1 and hole concentrations of 1017–1018 cm-3. The physical and chemical structures of SnO films were characterized by X-ray diffraction analysis and X-ray photoemission spectroscopy. It is concluded that amorphous and SnO-dominant films were obtained as deposited. Further annealing at ≤300 °C induces crystallization but no major chemical reaction. The transmission line method was adopted to characterize the contact resistance between SnO layers and various metal electrodes. Results show that Mo and Ni could be used as effective electrodes for p-type SnO, avoiding the use of noble metals. Finally, p-type SnO TFTs using practical metal electrodes were fabricated, where a field-effect mobility of up to 1.8 cm2 V-1 s-1 and an on/off current ratio of >103 were achieved.