Compositional Engineering of Cu-Doped SnO Film for Complementary Metal Oxide Semiconductor Technology

Metal oxide semiconductor (MOS)-based complementary thin-film transistor (TFT) circuits have broad application prospects in large-scale flexible electronics. To simplify circuit design and increase integration density, basic complementary circuits require both p- and n-channel transistors based on an individual semiconductor. However, until now, no MOSs that can simultaneously show p- and n-type conduction behavior have been reported. Herein, we demonstrate for the first time that Cu-doped SnO (Cu:SnO) with HfO₂ capping can be employed for high-performance p- and n-channel TFTs. The interstitial Cu⁺ can induce an n-doping effect while restraining electron-electron scatterings by removing conduction band minimum degeneracy. As a result, the Cu_3 atom %:SnO TFTs exhibit a record high electron mobility of 43.8 cm² V^-1 s^-1. Meanwhile, the p-channel devices show an ultrahigh hole mobility of 2.4 cm² V^-1 s^-1. Flexible complementary logics are then established, including an inverter, NAND gates, and NOR gates. Impressively, the inverter exhibits an ultrahigh gain of 302.4 and excellent operational stability and bending reliability.