Effects of P-Type SnO_x Thin-Film Transistors with N₂ and O₂ Ambient Furnace Annealing

Recently oxide-based thin-film transistors (TFTs) are investigated for emerging applications of the next generation display devices and other electronic circuits (Fortunato, E., et al., 2012. Oxide semiconductor thin-film transistors: A review of recent advances. Advanced Materials, 24, pp.2945-2986). Despite of the great success in n-type oxide semiconductors with high transparency and high field-effect mobility, high performance P-type oxide TFTs are so highly desired that complementary circuits can be realized with low power and high performance (Ou, W.C., et al., 2008. Anomalous P-channel amorphous oxide transistors based on tin oxide and their complementary circuits. Applied Physics Letters, 92, p.122113). There are some oxides such as SnO, CuO, Cu₂O and NiO are regarded as promising P-type semiconductor materials. In this investigation, tin oxide SnO_x is fabricated to be active layer for TFTs device, and furnace annealing with several combinations of nitrogen and oxygen ambient is compared to enhance the electrical characteristics of P-type SnO_x TFTs (Park, K.S., et al., 2009. High performance solution-processed and lithographically patterned zinc-tin oxide thin-film transistors with good operational stability. Electrochemical and Solid-State Lett., 12, pp.H256-H258). The results show that with N₂+O₂ ambient, 30 minutes furnace annealing, the P-type SnO TFTs device shows better performance with mobility (μ_FE) 0.883 cm²/V · S, threshold voltage (V) -4.63 V, subthreshold swing (SS) 1.15 V/decade, and I_on/I_off ratio 1.01×10₃.