Growth of two-dimensional single crystal materials controlled by atomic steps

Since the successful mechanical exfoliation of graphene in 2004, two-dimensional materials have aroused extensive research and fast developed in various fields such as electronics, optoelectronics and energy, owing to their unique structural and physicochemical properties. In terms of synthesis methods, researchers have made further advancements in the atomic step method, building upon traditional techniques such as mechanical exfoliation, liquid-phase exfoliation, vapor-phase deposition, wet chemical synthesis, and nanomaterial self-assembly. These efforts aim to achieve high-quality large-scale two-dimensional single crystal materials. In this article, the representative research on the growth of two-dimensional single crystal materials controlled by atomic steps in recent years is reviewed in detail. To begin with, the research background is briefly introduced, then the main synthesis methods of two-dimensional single crystal materials are discussed and the challenges and reasons for the difficulty in epitaxially preparing non-centrosymmetric materials are analyzed. Subsequently, the growth mechanisms and recent advances in the preparation of two-dimensional single crystal materials assisted by atomic steps are presented. The theoretical basis and universality of atomic step-controlled nucleation in two-dimensional single crystal material are analyzed. Furthermore, the challenges and future directions for achieving large-scale, directionally controllable two-dimensional single crystal materials are predicted. Finally, potential applications of the step method in the future scalable chip device fabrication are systematically discussed.