Tunneling Junction as Cold Source: Toward Steep-Slope Field-Effect Transistors Based on Monolayer MoS 2

In ultrascaled field-effect transistors (FETs), the thermionic limit to subthreshold swing (SS) represents a serious issue impeding their low-power application. Here, we propose a novel tunneling cold source FET (TCS-FET) to realize steep-slope (with SS less than 60 mV/dec) low-power devices, in which a p-n junction serves as cold source as a result of self-filtering of the electronic thermionic tail. Our first-principles calculations on the electrical properties of the TCS-FET based on monolayer MoS2 predict that large ON/OFF current ratio ( ${I}_{ \mathrm{\scriptscriptstyle ON}} / {I}_{ \mathrm{\scriptscriptstyle OFF}}$ ) up to $1.6 \times 10^{9}$ and steep SS as small as 32 mV/dec can be obtained. Moreover, by considering atomic doping at the source, we demonstrate that defects engineering is effective in optimizing both ${I}_{ \mathrm{\scriptscriptstyle ON}} / {I}_{ \mathrm{\scriptscriptstyle OFF}}$ and SS of the devices. This study is important for guiding the design of nanoscale steep-slope FETs based on 2-D materials.