Channel Length Scaling of MoS₂ MOSFETs

TLDR

The study investigates electrical transport in ultrathin MoS₂ MOSFETs with channel lengths from 2 µm to 50 nm, comparing devices of varying thicknesses to assess short‑channel behavior. The authors examine electrical transport in these ultrathin MoS₂ transistors across the 2 µm–50 nm channel length range. MoS₂ MOSFETs exhibit excellent immunity to short‑channel effects, showing no degradation at 100 nm channels with 5 nm MoS₂ and 300 nm SiO₂, achieving on/off ratios up to ~10⁹, while on‑current saturation arises from carrier velocity limits and overall performance is ultimately constrained by high Schottky‑barrier contact resistance, necessitating transparent contacts for high‑performance short channels.

Abstract

In this article, we investigate electrical transport properties in ultrathin body (UTB) MoS(2) two-dimensional (2D) crystals with channel lengths ranging from 2 μm down to 50 nm. We compare the short channel behavior of sets of MOSFETs with various channel thickness, and reveal the superior immunity to short channel effects of MoS(2) transistors. We observe no obvious short channel effects on the device with 100 nm channel length (L(ch)) fabricated on a 5 nm thick MoS(2) 2D crystal even when using 300 nm thick SiO(2) as gate dielectric, and has a current on/off ratio up to ~10(9). We also observe the on-current saturation at short channel devices with continuous scaling due to the carrier velocity saturation. Also, we reveal the performance limit of short channel MoS(2) transistors is dominated by the large contact resistance from the Schottky barrier between Ni and MoS(2) interface, where a fully transparent contact is needed to achieve a high-performance short channel device.