Ultrathin Al‐Assisted Al2O3 Passivation Layer for High‐Stability Tungsten Diselenide Transistors and Their Ambipolar Inverter

Abstract 2D transition metal dichalcogenides (TMDs) have recently received significant attention owing to their superior electrical, optical, and mechanical properties. However, most previous research on TMDs has not focused on their stability against bias and illumination stress. Here, high‐stability tungsten diselenide (WSe 2 ) field‐effect transistors (FETs) are introduced with an ultrathin Al‐assisted alumina (Al 2 O 3 ) passivation. Through the Al‐assisted Al 2 O 3 passivation, the transport behavior of the WSe 2 FETs is converted from p‐type to ambipolar owing to the n‐type doping effect of Al 2 O 3 passivation. Furthermore, the stability of the WSe 2 FETs is highly improved against gate bias and illumination stress owing to the effect of Al 2 O 3 film quality on WSe 2 by ultrathin Al predeposition ( ≈ 1 nm). To compare the stress effect on the electrical characteristics, three types of devices: 1) pristine WSe 2 FETs, 2) WSe 2 FET with Al 2 O 3 passivation layer, and 3) WSe 2 FETs with Al‐assisted Al 2 O 3 passivation layer, are systematically tested with positive gate bias stress (PBS) and positive gate bias illumination stress (PBIS). Finally, an ambipolar inverter composed of Al‐assisted Al 2 O 3 passivated WSe 2 FETs is demonstrated. This study proposes a promising approach that improves the stability of TMD‐based FETs for next‐generation logic applications.