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. This article is protected by copyright. All rights reserved.