Thickness Scaling Effect on Interfacial Barrier and Electrical Contact to Two-Dimensional MoS2 Layers

TL;DR

This study investigates how the thickness of MoS2 layers influences interfacial barriers and electrical contact properties with gold electrodes, revealing a crossover behavior around 5 layers and the ability to tune energy barriers.

Contribution

It demonstrates the thickness-dependent crossover in contact resistivity and provides a detailed energy level alignment evolution, offering new insights for interface engineering in 2D materials.

Findings

Contact resistivity decreases for MoS2 thicker than 5 layers

Contact resistivity sharply increases below 5 layers due to quantum confinement

Interfacial potential barrier can be tuned from 0.3 to 0.6 eV by varying thickness

Abstract

Understanding the interfacial electrical properties between metallic electrodes and low dimensional semiconductors is essential for both fundamental science and practical applications. Here we report the observation of thickness reduction induced crossover of electrical contact at Au/MoS2 interfaces. For MoS2 thicker than 5 layers, the contact resistivity slightly decreases with reducing MoS2 thickness. By contrast, the contact resistivity sharply increases with reducing MoS2 thickness below 5 layers, mainly governed by the quantum confinement effect. It is found that the interfacial potential barrier can be finely tailored from 0.3 to 0.6 eV by merely varying MoS2 thickness. A full evolution diagram of energy level alignment is also drawn to elucidate the thickness scaling effect. The finding of tailoring interfacial properties with channel thickness represents a useful approach controlling the metal/semiconductor interfaces which may result in conceptually innovative functionalities.