Hexagon Flower Quantum Dot-like Cu Pattern Formation during Low-Pressure Chemical Vapor Deposited Graphene Growth on a Liquid Cu/W Substrate

The H₂-induced etching of low-dimensional materials is of significant interest for controlled architecture design of crystalline materials at the micro- and nanoscale. This principle is applied to the thinnest crystalline etchant, graphene. In this study, by using a high H₂ concentration, the etched hexagonal holes of copper quantum dots (Cu QDs) were formed and embedded into the large-scale graphene region by low-pressure chemical vapor deposition on a liquid Cu/W surface. With this procedure, the hexagon flower-etched Cu patterns were formed in a H₂ environment at a higher melting temperature of Cu foil (1090 °C). The etching into the large-scale graphene was confirmed by optical microscopy, atomic force microscopy, scanning electron microscopy, and Raman analysis. This first observation could be an intriguing case for the fundamental study of low-dimensional material etching during chemical vapor deposition growth; moreover, it may supply a simple approach for the controlled etching/growth. In addition, it could be significant in the fabrication of controllable etched structures based on Cu QD patterns for nanoelectronic devices as well as in-plane heterostructures on other low-dimensional materials in the near future.