Van der Waals epitaxial growth of two-dimensional single-crystalline GaSe domains on graphene
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Escuela Politecnica Nacional, Quito (Ecuador)
Two-dimensional (2D) van der Waals (vdW) heterostructures are a family of artificially-structured materials that promise tunable optoelectronic properties for devices with enhanced functionalities. Compared to stamping, direct epitaxy of vdW heterostructures is ideal for clean interlayer interfaces and scalable device fabrication. Here, we explore the synthesis and preferred orientations of 2D GaSe atomic layers on graphene (Gr) by vdW epitaxy. Guided by the wrinkles on graphene, GaSe nuclei form that share a predominant lattice orientation. Due to vdW epitaxial growth many nuclei grow as perfectly aligned crystals and coalesce to form large (tens of microns), single-crystal flakes. Through theoretical investigations of interlayer energetics, and measurements of preferred orientations by atomic-resolution STEM and electron diffraction, a 10.9 interlayer rotation of the GaSe lattice with respect to the underlying graphene is found to be the most energetically preferred vdW heterostructure with the largest binding energy and the longest-range ordering. These GaSe/Gr vdW heterostructures exhibit an enhanced Raman E21g band of monolayer GaSe along with highly-quenched photoluminescence due to strong charge transfer. Despite the very large lattice mismatch of GaSe/Gr through vdW epitaxy, the predominant orientation control and convergent formation of large single-crystal flakes demonstrated here is promising for the scalable synthesis of large-area vdW heterostructures for the development of new optical and optoelectronic devices.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1214495
- Journal Information:
- ACS Nano, Vol. 9, Issue 8; ISSN 1936-0851
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Revealing the preferred interlayer orientations and stackings of two-dimensional bilayer gallium selenide crystals
Two-dimensional GaSe/MoSe2 misfit bilayer heterojunctions by van der Waals epitaxy