Reduced Fermi Level Pinning at Physisorptive Sites of Moire-MoS2/Metal Schottky Barriers

Zhaofu Zhang; Yuzheng Guo; John Robertson

doi:10.1021/acsami.1c23918

Reduced Fermi Level Pinning at Physisorptive Sites of Moire-MoS₂/Metal Schottky Barriers

ACS Appl Mater Interfaces. 2022 Mar 9;14(9):11903-11909. doi: 10.1021/acsami.1c23918. Epub 2022 Feb 27.

Authors

Zhaofu Zhang¹, Yuzheng Guo², John Robertson¹

Affiliations

¹ Department of Engineering, University of Cambridge, Cambridge CB3 0FA, U.K.
² School of Electrical Engineering, Wuhan University, Wuhan 430072, China.

Abstract

Weaker Fermi level pinning (FLP) at the Schottky barriers of 2D semiconductors is electrically desirable as this would allow a minimizing of contact resistances, which presently limit device performances. Existing contacts on MoS₂ have a strong FLP with a small pinning factor of only ∼0.1. Here, we show that Moire interfaces can stabilize physisorptive sites at the Schottky barriers with a much weaker interaction without significantly lengthening the bonds. This increases the pinning factor up to ∼0.37 and greatly reduces the n-type Schottky barrier height to ∼0.2 eV for certain metals such as In and Ag, which can have physisorptive sites. This then accounts for the low contact resistance of these metals as seen experimentally. Such physisorptive interfaces can be extended to similar systems to better control SBHs in highly scaled 2D devices.

Keywords: Fermi level pinning; MoS2; Schottky barriers; metal contacts; physisorptive sites.