Tuning Positive and Negative Transconductance in Multilayer MoS2 with Indium Contacts

We report unusual behavior in the transconductance of multilayer MoS2 at a low temperature. Multilayer MoS2 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 MoS2 and become more prominent as the sample thickness increases. Our results provide further insights for carrier transport in multilayer MoS2 and its practical applications.