Solution processed vertical p-channel thin film transistors using copper(i) thiocyanate

Abstract

Here, we present a strategy for the realization of p-channel inorganic thin film transistors (TFTs) based on vertically stacked contacts and a copper(I) thiocyanate (CuSCN) semiconductor. The CuSCN semiconductor was generated by a simple low-temperature (ca. 100 °C) solution-based process. Utilizing the vertical architecture, channel length was determined by the thickness of the CuSCN film. This readily endows transistors with ultrashort channel lengths (<700 nm) to afford delivering drain current greatly exceeding that of conventional planar TFTs. Thus, high normalized transconductance of 0.84 S m⁻¹ and current density of 248 mA cm⁻² can be achieved for CuSCN-based vertical TFTs. To further improve the device's performance, we doped SnCl₂ into the semiconductor film. By doping SnCl₂ into CuSCN, shallow acceptor states that could induce additional holes were generated above the valence band maximum. The SnCl₂-doped TFTs showed enlarged transconductance and current density values of 1.8 S m⁻¹ and 541 mA cm⁻², respectively, which are comparable with those of other high performance vertical transistors. The p-channel inorganic TFTs developed in this study can open up exciting opportunities in complementary circuits, display switching, and flexible electronics.