Impact of Gate Dielectrics on the Threshold Voltage in MoS2 Transistors

The electrical characteristics of field-effect transistors based on 2D materials such as MoS2 strongly depend on defects in various regions of the device. Thus, an accurate description of charge transfer reactions with defects is essential as they have a strong impact on several important performance parameters. In particular, they disturb the electrostatic control of the gate over the channel, which is one of the central advantages of 2D devices in the ultimate scaling limit. As a consequence of charge trapping in these defects, large threshold voltage shifts are possible on short (hysteresis) and long (drift) timescales, which prohibit stable device operation. Here we introduce a drift-diffusion based simulation methodology coupled to a non-radiative multiphonon model to describe charge transfer reactions. Our results shed light on the interaction of defects with the 2D channel, which is important to enable further progress in the area of 2D based transistors.