In-plane template induced selective growth of H-phase CrSe2

Abstract Phase engineering in two-dimensional transition metal dichalcogenides (2D-TMDs) offers opportunities for exploring their unique properties of different phases and achieving new desired functionalities. Here, we report a selective synthetic strategy for the molecular beam epitaxy growth of the H-phase CrSe2 induced by an in-plane heteroepitaxial template. The lattice-matched MoSe2 nanoribbons are utilized as the in-plane heteroepitaxial template to seed the growth of H-phase CrSe2 thin layers with the consequential formation of MoSe2-CrSe2 lateral heterostructures. Scanning tunneling microscopy and non-contact atomic force microscopy studies reveal the atomically sharp interfaces in the lateral heterostructures and the characteristic defects of mirror twin boundaries emerging in the H-phase CrSe2 monolayers. Distinct from the metallic T-phase CrSe2, the semiconducting character of the H-phase CrSe2 is detected using the scanning tunneling spectroscopy. The type-I straddling band alignments of MoSe2-CrSe2 lateral heterostructures are directly visualized in atomic precision with band bending at the interfaces. The mirror twin boundaries in the H-phase CrSe2 exhibit the Tomonaga-Luttinger liquid behavior in the confined one-dimensional electronic system. This in-plane heteroepitaxial template induced phase-selective growth provides a promising approach for phase engineering of 2D TMDs, thereby further expanding the library of crystal phases and promoting the versatile device applications of specific phases.