In Situ Measurements of Strain Evolution in Graphene/Boron Nitride and Transition Metal Dichalcogenide Heterostructures Using a Non-Destructive Raman Spectroscopy Approach

Strain engineering is a promising method to manipulate the electronic and optical properties of two-dimensional (2D) materials. In this study, non-destructive Raman spectroscopy was used to investigate the strain evolution of single-layer graphene (SLGr), few-layer boron nitride/graphene (FLBN/SLGr) heterostructures, and transition metal dichalcogenides (TMDs). The prepared 2D materials are synthesized via the chemical vapor deposition method and then transferred to a flexible polyethylene terephthalate substrate for strain measurement. For this study, a customized mechanical device-jig to be used as an insert for the 3D piezoelectric stage of the Raman system was designed and manufactured in-house. In situ investigation of the effects of applied strain in graphene detectable via Raman spectral data in characteristic bonds within SLGr and FLBN/SLGr heterostructures is carried out. SLG exhibited higher Raman shifts in the 2D band at the same strain range compared to the FLBN/SLGr heterostructure. Additionally, we used the same approach to investigate strain evolution in various TMDs and their heterostructures. This study presents an important pathway for designing 2D material heterostructures and flexible devices.