Controllable Growth of Thick-Layer Graphene or Graphite on Copper by Tuning Silicon Additives

The synthesis of multilayer van der Waals (vdW) film materials has attracted considerable interest in both fundamental and applied research. Recently, methods for synthesizing multilayer graphene films or graphite on single-crystal nickel foils are developed. However, the chemical vapor deposition (CVD) synthesis of thick-layer graphene films or graphite (TLG) on copper substrates remains a significant challenge due to the self-limiting growth phenomenon. In this study, a novel method to grow TLG on copper substrates by controlling the silicon additive is presented. The as-grown TLG exhibits high quality, with controllable thickness from a few layers to tens of nanometers. The growth of TLG films is achieved by the synchronous growth of multilayer graphene islands on a silicide copper surface, which is likely to be in a liquid state according to the Cu-Si phase diagram. On the Cu-Si surface, all graphene layers grow synchronously, circumventing the self-limiting mechanism and the antiwedding cake growth or wedding cake mode of van der Waals material growth. Based on this synchronous growth mode, the thickness of TLG can be precisely controlled, ranging from a few to tens of nanometers. The study provides a facile and scalable way to synthesize high-quality thick vdW films for various applications.