Epitaxial Single‐Crystal Growth of Transition Metal Dichalcogenide Monolayers via the Atomic Sawtooth Au Surface

Abstract

Growth of 2D van der Waals layered single‐crystal (SC) films is highly desired not only to manifest the intrinsic physical and chemical properties of materials, but also to enable the development of unprecedented devices for industrial applications. While wafer‐scale SC hexagonal boron nitride film has been successfully grown, an ideal growth platform for diatomic transition metal dichalcogenide (TMdC) films has not been established to date. Here, the SC growth of TMdC monolayers on a centimeter scale via the atomic sawtooth gold surface as a universal growth template is reported. The atomic tooth‐gullet surface is constructed by the one‐step solidification of liquid gold, evidenced by transmission electron microscopy. The anisotropic adsorption energy of the TMdC cluster, confirmed by density‐functional calculations, prevails at the periodic atomic‐step edge to yield unidirectional epitaxial growth of triangular TMdC grains, eventually forming the SC film, regardless of the Miller indices. Growth using the atomic sawtooth gold surface as a universal growth template is demonstrated for several TMdC monolayer films, including WS2, WSe2, MoS2, the MoSe2/WSe2 heterostructure, and W1−xMoxS2 alloys. This strategy provides a general avenue for the SC growth of diatomic van der Waals heterostructures on a wafer scale, to further facilitate the applications of TMdCs in post‐silicon technology.

Recent Progress on Two-Dimensional Materials

“…Inspired by the success of h-BN on vicinal Cu(111) surface 99 , centimeter-scale single-crystalline MoS2 monolayer has been recently successfully realized on vicinal Au(111) surfaces 924 . Soon after, the growth of centimeter-scale single-crystalline TMD monolayers, including WS2, WSe2, MoS2, MoSe2/WSe2 heterostructure, and even W1−xMoxS2 alloy, on various high-index Au surfaces was reported 1668 . These experimental successes confirm the effectiveness of using low- symmetry substrate to template 2D materials epitaxy.…”

Self-aligned stitching growth of centimeter-scale quasi-single-crystalline hexagonal boron nitride monolayers on liquid copper

“…Note that visual inspection of unidirectionally aligned triangular grains and voids has become a reliable criterion to evidence the large-area epitaxial single-crystal growth of TMDs on atomic sawtooth gold surface. 35 Thus, based on the centimeter-scale universal aligned grains and coherent voids shown in Fig. 2, we can reasonably deduce that self-aligned seamless stitching growth of quasi-single-crystalline hBN on liquid Cu is a facile and scalable route.…”

Single-crystal two-dimensional material epitaxy on tailored non-single-crystal substrates

“…1b, c ) are also applicable for graphene and hBN grown on other twin FCC metal substrates if the epitaxial relationship of a zigzag direction of a 2D material aligning along a high symmetric <110> direction of a substrate stands 32 , 33 . For example, Au substrates are promising for the epitaxial growth of transition metal dichalcogenides (TMDCs) 34 , 35 , sharing the same epitaxial relationship as that of hBN on Cu surface. Due to the same 3-fold symmetry of TMDCs and hBN crystal lattices, the alignment TMDCs on a twinned Au substrate is the same as that of hBN on a twinned Cu substrate of same type and, thus, the synthesis of single-crystal TMDCs on twinned Au surfaces is possible.…”