Where Does the Current Flow in Two-Dimensional Layered Systems?

Saptarshi Das, Birck Nanotechnology Center, Purdue University
Joerg Appenzeller, Birck Nanotechnology Center, Purdue University

Date of this Version



In this Letter, we map for the first time the current distribution among the individual layers of multilayer two-dimensional systems. Our findings suggest that in a multilayer MoS2 field-effect transistor the "HOT-SPOT" of the current flow migrates dynamically between the layers as a function of the applied back gate bias and manifests itself in a rather unusual "contact resistance" that cannot be explained using the conventional models for metal-to-semiconductor contacts. To interpret this unique, contact resistance, extracted from a channel length scaling study, we employed a resistor network model based on Thomas-Fermi charge screening and interlayer coupling. By modeling our experimental data we have found that the charge screening length for MoS2 is rather large (lambda(MoS2) = 7 nm) and translates into a current distribution in multilayer MoS2 systems, which is distinctly different from the current distribution in multilayer graphene (lambda(graphene) = 0.6 nm). In particular, our experimental results allow us to retrieve for the first time fundamental information about the carrier transport in two-dimensional layered systems that will likely play an important role in the implementation of future electronics components but that have not been evaluated in the past.


Nanoscience and Nanotechnology