Tuning Positive and Negative Transconductance in Multilayer MoS2 with Indium Contacts

Abstract

We report unusual behavior in the transconductance of multilayer ${\mathrm{Mo}\mathrm{S}}_{2}$ at a low temperature. Multilayer ${\mathrm{Mo}\mathrm{S}}_{2}$ with indium top contacts exhibits negative transconductance at an intermediate back-gate bias and reentrant positive transconductance at a higher back-gate bias. We further determine that the transconductance can be modulated via controlling the channel length, which originates from competition between the intralayer in-plane transport and interlayer vertical transport. These features emerge owing to the van der Waals contact between indium and ${\mathrm{Mo}\mathrm{S}}_{2}$ and become more prominent as the sample thickness increases. Our results provide further insights for carrier transport in multilayer ${\mathrm{Mo}\mathrm{S}}_{2}$ and its practical applications.