Tunneling Junction as Cold Source: Toward Steep-Slope Field-Effect Transistors Based on Monolayer MoS<sub>2</sub>
Qianwen Wang, Pengpeng Sang, Fei Wang, Wei Wei, Jiezhi Chen
Abstract
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 MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> predict that large ON/OFF current ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{ \mathrm{\scriptscriptstyle ON}} / {I}_{ \mathrm{\scriptscriptstyle OFF}}$ </tex-math></inline-formula> ) up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.6 \times 10^{9}$ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{ \mathrm{\scriptscriptstyle ON}} / {I}_{ \mathrm{\scriptscriptstyle OFF}}$ </tex-math></inline-formula> and SS of the devices. This study is important for guiding the design of nanoscale steep-slope FETs based on 2-D materials.