Two-dimensional sheet resistance model for polycrystalline graphene with overlapped grain boundaries

Abstract

Overlapped grain boundaries (OGBs) are an important feature of two-dimensional (2D) materials that are electrically, mechanically, and thermally different from conventional grain boundaries (CGBs). The properties of an individual OGB have been explored in some microscopic studies, but the effects of OGBs on the macroscopic properties of 2D materials such as sheet resistance and mobility have rarely been investigated. Therefore, it is necessary to identify and formulate the influence of the OGBs on the macroscopic properties of 2D materials. In this study, we propose a 2D sheet resistance and mobility model for polycrystalline graphene that considers the effects of OGBs and intra-grain defects. The proposed model is supported by a simulation of the growth and sheet resistance of graphene grown by chemical vapor deposition (CVD). The electrical properties were investigated with respect to the average grain size, and a threshold grain size for mobility saturation was introduced, which can provide directions for the growth of high-quality 2D materials for commercial use. Moreover, the 2D characteristics reflected in the model can explain the variation in the sheet resistance and mobility of graphene grown under the same conditions. Since this model is applicable to general 2D materials, it will provide guidelines for the growth of various 2D materials.