Channel Length Scaling of MoS2 MOSFETs

Abstract

In this article, we investigate electrical transport properties in ultrathin body (UTB) MoS₂ 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 MoS₂ transistors. We observe no obvious short channel effects on the device with 100 nm channel length (L_ch) fabricated on a 5 nm thick MoS₂ 2D crystal even when using 300 nm thick SiO₂ as gate dielectric, and has a current on/off ratio up to ∼10⁹. 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 MoS₂ transistors is dominated by the large contact resistance from the Schottky barrier between Ni and MoS₂ interface, where a fully transparent contact is needed to achieve a high-performance short channel device.