Abnormal Grain Growth for Single-Crystal Cu Substrate and Chemical Vapor Deposition of Graphene on It

Abstract

In this study, we optimized the condition for forming a single-crystal (111) Cu substrate by using polycrystalline Cu and an abnormal grain growth method. As a result, a single-crystal (111) Cu surface could be formed through annealing for 2 hours in an H₂ (100 sccm) and Ar (200 sccm) gas atmosphere (pressure 70 Torr) at 1050 °C. The crystallinity of the Cu-surface was confirmed by using X-ray diffraction analysis and electron backscatter diffraction (EBSD) pattern imaging and mapping. In addition, chemical vapor deposited graphene was synthesized before and after the crystallinity control of the substrate, and then transferred onto an SiO₂ (300 nm)/Si substrate to perform a Raman spectral analysis and to evaluate the electrical properties through graphene field effect transistor device fabrication. In particular, the mobility of graphene grown on polycrystalline Cu is μ_h = 1228 (μ_e = 1158) cm²·V⁻¹·s⁻¹ while the carrier mobility of graphene synthesized on a single-crystal Cu surface is μ_h = 3353 (μ_e = 3200) cm²·V⁻¹·s⁻¹, showing an improvement of about 273% (276%). Such a single-crystal substrate can be widely used for the synthesis of high-quality 2-dimensional materials and can be reused after the material has been transferred by using a metal etching-free transfer method.