Restoring Ultra-Flat Bridgman-Fabricated Single-Crystal Cu(111) Wafers via Recrystallization Arrest Strategy for High-Quality Graphene Epitaxy.

Abstract

Single-crystal Cu(111) and its ultra-flat surface are crucial for the heteroepitaxy of high-quality, single-crystal graphene films with minimal folds and additional layers. Bridgman method coupled with cutting and chemical-mechanical polishing presents a straightforward and cost-effective approach for preparing ultra-flat Cu(111) wafers but is simply discarded due to its incompatibility with standard high-temperature procedures for annealing and graphene growth. Herein, an in-depth investigation is conducted into the mechanisms of recrystallization and reverse single-crystallization induced by processing strain and dislocations. A recrystallization arrest strategy is proposed for Bridgman-cutting-polishing (BCP) derived Cu(111) wafers, guaranteeing the high single-crystallinity (96.6%) and flatness (0.81 nm) of epitaxy substrates. The thorough investigation has provided a comprehensive understanding of the effects of surface roughness on the orientation, proportion of adlayers, as well as transfer qualities of graphene films. By highlighting the paramount importance of the Bridgman cutting-polishing methodology, the efforts set the stage for achieving notable cost savings in the manufacture of ultra-flat, single-crystal graphene wafers.