Growth of Two-Dimensional Materials at the Wafer Scale

Wafer-scale growth has become a critical bottleneck for scaling up applications of van der Waal (vdW) layered two-dimensional (2D) materials in high-end electronics and optoelectronics. Most vdW 2D materials were initially obtained through top-down synthesis methods, such as exfoliation, which can only prepare small flakes on a micrometer scale. Bottom-up growth can enable 2D flake growth over a large area. However, seamless merging of these flakes to form large-area continuous films with well-controlled layer thickness and lattice orientation is still a significant challenge. In this review, we briefly introduce several vdW layered 2D materials covering their lattice structures, representative physical properties, and potential roles in large-scale applications. Then, several methods used to grow vdW layered 2D materials at the wafer-scale are reviewed in depth. In particular, we summarize three strategies that enable 2D film growth with a single-crystalline structure over the whole wafer: growth of an isolated domain, growth of unidirectional domains, and conversion of oriented precursors. After that, we review the progress in using wafer-scale 2D materials in integrated devices and advanced epitaxy. Finally, future directions in the growth and scaling of vdW layered 2D materials are discussed.