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 (WSe2) field-effect transistors (FETs) are introduced with an ultrathin Al-assisted alumina (Al2O3) passivation. Through the Al-assisted Al2O3 passivation, the transport behavior of the WSe2 FETs is converted from p-type to ambipolar owing to the n-type doping effect of Al2O3 passivation. Furthermore, the stability of the WSe2 FETs is highly improved against gate bias and illumination stress owing to the effect of Al2O3 film quality on WSe2 by ultrathin Al predeposition (approximate to 1 nm). To compare the stress effect on the electrical characteristics, three types of devices: 1) pristine WSe2 FETs, 2) WSe2 FET with Al2O3 passivation layer, and 3) WSe2 FETs with Al-assisted Al2O3 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 Al2O3 passivated WSe2 FETs is demonstrated. This study proposes a promising approach that improves the stability of TMD-based FETs for next-generation logic applications.