High Performance, Sub-thermionic MoS2 Transistors using Tunable Schottky Contacts

Abstract

The inability to scale $\mathrm{V}_{\mathrm{dd}}$ owing to the Boltzmann limit (Sub-threshold Slope $(SS)=60\mathrm{mV}/\mathrm{dec}$ @ 300 K) has been the primary bottleneck in obtaining power efficient scaled transistors [1]. Two-dimensional semiconductors owing to their naturally ultra-thin body offer excellent opportunities for highly scaled nano-transistors [4]. However, explorations of sub-thermionic devices on these materials have been heavily stymied owing to inefficient doping, contacts and dielectric integration. In this work, we attempt to combine the excellent SS of the TFET with the high $\mathrm{I}_{\mathrm{on}}$ of the thermionic MOSFET employing effective device design and materials processing. We adopt a conscious design strategy to use Schottky contacts as switching elements, which, unlike BTBT junctions allow for both thermionic (high $\mathrm{I}_{\mathrm{on}}$) AND tunneling (very steep SS) dominated operational modes. A plausible conduction mechanism is elucidated which agrees well with experimental results.