마이크로 및 나노와이어 에피택시를 이용한 그래핀의 결정 구조 감정

Abstract

Monitoring crystallographic orientations of graphene is important for the reliable generation of graphene-based nanostructures such as van der Waals heterostructures and graphene nanoribbons, since their physical properties are dependent on crystal structures. However, facile and precise identification of graphene’s crystallographic orientations is still challenging because the majority of current tools rely on complex atomic-scale imaging. Here, we quantitatively verifies an identification method for the crystal orientation and grain boundaries of graphene using the directional alignment between AuCN nanowires or AgCN microwires and the underlying graphene. Since the AuCN nanowires are visible in scanning electron microscopy and the AgCN microwires are visible in conventinal optical microscopy, crystal orientations of graphene can be inspected with simple procedures. Kernel density estimation we used in analyzing the nanowire and microwire directions enables a precise measurement of graphene’s crystal orientations. We also confirm that the imaged AuCN nanowires and AgCN mcirowires can be simply removed without degrading graphene’s quality, thus showing that the present method can be practically used for measuring graphene’s crystal structures.