Epitaxial growth of wafer-scale two-dimensional material have been intensively studied for reasons of application needs. Recent achievements include wafer-scale boron nitride (Nature 2020, 579, 219-223; Nature 2019, 570, 91-95), graphene (Nat. Mater. 2016, 15, 43-47) and transition-metal dichalcogenides (TMDs, Nat. Nanotechnol. 2021, 16, 1201-1207; Nat. Nanotechnol. 2022, 17, 33-38). In this report, I shall briefly introduce our recent work on the molecular beam epitaxy (MBE) growth of single-crystal MoSe₂ and WSe₂ monolayers on gold substrates at the wafer-scale. MBE growth was performed at relatively lower temperatures compared to chemical vapor deposition (CVD) and the epifilms have a defect density of low 10¹² cm^-2. The epifilms can be transferred to other substrates such as SiO₂/Si and optical measurements indicate good uniformity. The interaction between the epifilms and gold substrates is suggested to be of van der Waals interaction while the high crystallinity is led by enhanced edge interaction.

Dr. Yipu Xia received his Ph.D. at the University of Hong Kong. He is now a postdoctoral fellow at the University of Hong Kong under the guidance of Prof. Maohai Xie. Yipu Xia’s research interests focus on experimental condensed matter physics, especially thin film growth by molecular beam epitaxy and low-dimensional studies by scanning tunneling microscopy. Recently his research areas include the growth of two-dimensional transitional metal dichalcogenides (MoSe₂, WSe₂, WTe₂, etc.) and one-dimensional Luttinger liquid studies.