Facile control of p-type SnO TFT performance with restraining redox reaction by ITO interlayers

By comparing Ni and ITO electrodes of SnO TFT, we find a facile method to control p-type SnO TFT performance. A Ni-electrode TFT has a high field-effect mobility of 3.3 cm2/Vs and a low on/off current ratio of 3.6 × 101. Compared to Ni, ITO-electrode TFT has low field-effect mobility of 1.4 cm2/Vs and a high on/off current ratio of 1.1 × 103. Using various analysis methods, we suggested why the electrical properties of SnO TFT differed depending on the electrode materials. First, a redox reaction occurs at the interface of SnO and Ni during the post-annealing process. Second, Ni has an ohmic-like contact formation with SnO, which lowers the Schottky barrier height of carriers. ITO ILs are adopted to Ni electrode to reduce the off-current by hindering the redox reaction. The off-current of TFTs is effectively reduced with ITO ILs as thickness increases. An ITO IL that is 10-nm thick yields the optimum electrical properties: field-effect mobility of 2.5 cm2/Vs, Ion/Ioff of 1.7 × 103 and Vth shift under NBS of −1.4 V.