Advances and Challenges in Atomic-Level Growth of Two-Dimensional Single Crystals

The exceptional electronic, optical, and quantum properties of two-dimensional (2D) single crystals have driven extensive research efforts aimed at developing scalable epitaxial methods for next-generation technologies. Of the various approaches available, atomic-level epitaxial growth has emerged as the most effective technique, enabling the epitaxy of wafer-scale single-crystal films with precise control over crystallographic orientation and thickness. However, it also presents significant challenges related to structural stability, lattice matching, and surface-interfacial engineering. In this review, we aim to summarize the latest representative advancements in the atomic-level epitaxy of large-area 2D single crystals, including conductors (e.g., graphene and borophene), semiconductors (e.g., phosphorene and transition metal dichalcogenides), and insulators (e.g., hexagonal boron nitride and metal oxides) and also discuss techniques for controlling defects and manipulating stacking order, highlighting strategies for achieving single nucleation, aligned multilayer islands, and heterostructure integration. Finally, we outline current challenges, such as thermodynamic instability, defect formation during nucleation, and scalability limitations, as well as offer a forward-looking perspective on how to accelerate the incorporation of 2D single crystals into next-generation electronic, optoelectronic, and quantum devices.