Subthermionic Steep-Slope MoS₂/MoO₃/MoS₂ Tunneling Field-Effect Transistor with Extremely Low Off-state Current Level

The growing demand for miniaturized semiconductor devices in advanced information technology has driven the rapid downscaling of field-effect-transistor (FET) designs. Moreover, conventional metal-oxide-semiconductor FETs exhibit a subthreshold swing (SS) of at least 60 mV per decade, which corresponds to the thermionic emission limit. Tunneling FETs (TFETs) based on two-dimensional (2D) transition-metal dichalcogenide (TMDs) have been widely studied to achieve subthermionic SS and further reduce the channel length. Here, we report a TFET fabricated using a MoS₂/MoO₃/MoS₂ vertical heterojunction, in which the tunneling current flows through the oxide layer. This oxide layer between the semiconductors impedes electron mobility, thereby mitigating the leakage currents. This significantly reduces the OFF-state current. The proposed design achieved a minimum subthermionic SS of 18.7 mV/dec and extremely low OFF state currents in the range of 10^-9-10^-10 μA/μm in the transfer characteristics. Moreover, temperature-dependent electrical characterization confirmed that both trap-assisted tunneling (TAT) and band-to-band tunneling (BTBT) affected the drain current. These findings offer significant potential for enabling large-area production of next-generation low-power devices based on 2D TMDs.