Single- and Few-Layer WTe2 and Their Suspended Nanostructures: Raman Signatures and Nanomechanical Resonances

TL;DR

This paper reports the isolation, characterization, and mechanical testing of single- and few-layer WTe2, revealing new Raman signatures and measuring their nanomechanical resonances, thus advancing understanding of this layered material's properties.

Contribution

It presents the first fabrication and analysis of suspended WTe2 nanostructures, including new Raman signatures and Young's modulus measurement.

Findings

New Raman signatures for few-layer WTe2 identified.

Young's modulus of suspended WTe2 flakes measured at ~80 GPa.

Successful fabrication of suspended WTe2 nanostructures.

Abstract

Single crystal tungsten ditelluride (WTe2) has recently been discovered to exhibit non-saturating extreme magnetoresistance in bulk; it has also emerged as a new layered material from which atomic layer crystals can be extracted. While atomically thin WTe2 is attractive for its unique properties, little study has been conducted on single- and few-layer WTe2. Here we report the isolation of single- and few-layer WTe2, as well as fabrication and characterization of the first WTe2 suspended nanostructures. We have observed new Raman signatures of few-layer WTe2 that have been theoretically predicted but not yet reported to date, in both on-substrate and suspended WTe2 flakes. We have further probed the nanomechanical properties of suspended WTe2 structures by measuring their flexural resonances, and obtain a Young's modulus of E_Y~80GPa for the suspended WTe2 flakes. This study paves the way for future investigations and utilization of the multiple new Raman fingerprints of single- and few-layer WTe2, and for exploring mechanical control of WTe2 atomic layers.