Non-epitaxial growth of highly oriented transition metal dichalcogenides with density-controlled twin boundaries

Twin boundaries (TBs) in transition metal dichalcogenides (TMDs) constitute distinctive one-dimensional electronic systems, exhibiting intriguing physical and chemical properties that have garnered significant attention in the fields of quantum physics and electrocatalysis. However, the controlled manipulation of TBs in terms of density and specific atomic configurations remains a formidable challenge. In this study, we present a non-epitaxial growth approach that enables the controlled and large-scale fabrication of homogeneous catalytically active TBs in monolayer TMDs on arbitrary substrates. Notably, the density achieved using this strategy is six times higher than that observed in convention chemical vapor deposition (CVD)-grown samples. Through rigorous experimental analysis and multigrain Wulff construction simulations, we elucidate the role of regulating the metal source diffusion process, which serves as the key factor for inducing the self-oriented growth of TMD grains and the formation of unified TBs. Furthermore, we demonstrate that this novel growth mode can be readily incorporated into the conventional CVD growth method by making a simple modification of the growth temperature profile, thereby offering a universal approach for engineering of grain boundaries in two-dimensional materials.Ministry of Education (MOE)Published versionThis work was supported by the National Key R&D Program of China (2018YFA0305800), Natural Science Foundation of China (51872285), the Beijing Outstanding Young Scientist Program (BJJWZYJH01201914430039), CAS Project for Young Scientists in Basic Research (YSBR-003), and the Fundamental Research Funds for the Central Universities. The work at NUAA was supported by the National Key R&D Program of China (2019YFA0705400) and Natural Science Foundation of China (1221101035, 12225205, 22073048), and the computations were in part performed at the High-performance Computational Center at NUAA. This work was also supported in part by the Singapore Ministry of Education AcRF Tier 2 (MOE2019-T2-2-105 and MOE-MOET2EP10121-0006) and AcRF Tier 1 (RG7/21)