Growth and Etching of the Grain Boundaries in Polygonal Graphene Islands.

The grain boundary is an intrinsic defect within mono- and multi-layer polygonal graphene islands during the chemical vapor deposition growth process. It greatly influences their mechanical and electronic properties. However, the precise characterization and formation mechanism of grain boundaries still remain unclear. In this work, H2 etching experiments show that a polygonal etched hole originates from the natural location of a grain boundary beyond the nucleation site in polygonal monolayer graphene. Furthermore, colorful Raman mapping provides a visualized method to explore the distribution of grain boundaries in polygonal bilayer graphene. Therefore, a deep understanding of the growth kinetics of mono- and bi-layer polygonal graphene was obtained through etching engineering combined with Raman spectroscopy.