Domain-boundary independency of Raman spectra for strained graphene at strong interfaces

Abstract

Strains in graphene play a significant role in graphene-based flexible devices, but many aspects of the domain boundary effects in strained graphene remain unclear, such as the evolution of Raman spectra. Here we present a systematic investigation on the domain boundary effects on the Raman spectra of strained graphene, using a designed strong interface formed by formvar resins. We achieve in single-crystal graphene by far the largest strain up to 2%, significantly improved from the previous highest value of 1.3%, as well as the redshift and splitting for its G and 2D peaks. More importantly, the Raman spectra of strained bi-crystal graphene with a domain boundary show that the spectral evolution follows the same trend as the single crystal, and this trend was also confirmed by the result in polycrystalline graphene, demonstrating that the straining effect on the G and 2D peaks of graphene at strong interfaces is actually independent of its domain boundaries, different from the previous report of graphene deposited on weak interfaces. We attribute it to the efficient interfacial stress transfer at the formvar interfaces, and believe they can provide new insights into the understanding of graphene mechanical behaviors and valuable guidance for graphene-based flexible electronics.