Two-Dimensional Heterojunction Interlayer Tunneling Field Effect Transistors (Thin-TFETs)

• Main Authors: Mingda Oscar Li, David Esseni, Joseph J. Nahas, Debdeep Jena, Huili Grace Xing
• Format: Article
• Language: English
• Published: IEEE 2015-01-01
• Series: IEEE Journal of the Electron Devices Society
• Subjects: Tunnel FET; 2-D crystals; transport model; steep slope; subthreshold swing (SS); layered materials
• Online Access: https://ieeexplore.ieee.org/document/7006653/

Layered 2-D crystals embrace unique features of atomically thin bodies, dangling bond free interfaces, and step-like 2-D density of states. To exploit these features for the design of a steep slope transistor, we propose a Two-dimensional heterojunction interlayer tunneling field effect transistor (Thin-TFET), where a steep subthreshold swing (SS) of ~14 mV/dec and a high on-current of ~300 μm are estimated theoretically. The SS is ultimately limited by the density of states broadening at the band edges and the on-current density is estimated based on the interlayer charge transfer time measured in recent experimental studies. To minimize supply voltage V_DD while simultaneously maximizing on currents, Thin-TFETs are best realized in heterostructures with near broken gap energy band alignment. Using the WSe₂/SnSe₂ stacked-monolayer heterostructure, a model material system with desired properties for Thin-TFETs, the performance of both n-type and p-type Thin-TFETs is theoretically evaluated. Nonideal effects such as a nonuniform van der Waals gap thickness between the two 2-D semiconductors and finite total access resistance are also studied. Finally, we present a benchmark study for digital applications, showing the Thin-TFETs may outperform CMOS and III-V TFETs in term of both switching speed and energy consumption at low-supply voltages.