Triaxial compressive strain in bilayer graphene enabled by nitride stressor layer

A technique that can be used to viably create triaxially strained bilayer graphene on any desirable location by simple patterning was developed. Unlike the conventional graphene strain engineering methods, the photolithographically defined spoke patterns and compressive strained Si₃N₄ layer deposited by plasma-enhanced chemical vapor deposition (PECVD) system enable the creation of locally confined triaxial strained bilayer graphene at the desire location by forming a unique tristar shaped wrinkle. The tristar shaped wrinkle was investigated with high resolution micro-Raman spectroscopy and atomic force microscopy (AFM) analyses, and confirmed that 0.38% of maximum triaxial compressive strain was created. Mechanical simulation was used to verify the strain distribution and confirm the strain value which was calculated from the Raman spectroscopy and AFM profile. The technique presented here not only provides a practical route to the creation of strained graphene at desired locations but also offers the potential of the creation of multiaxial strain in the graphene for various types of graphene-based electronic and optoelectronic devices.