Synthesis of Single Crystal Transition Metal Dichalcogenides on Au (111) Surface

Po-Sen Mao^1,2*, Guan-Hao Chen^1,2, Juhn-Jong Lin¹, Chun-Liang Lin¹, Wen-Hao Chang^1,2,3

¹1Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
²3Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
³4Center for Emergent Functional Matter Science (CEFMS), National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan

* Presenter:Po-Sen Mao, email:flannery0123.sc11@nycu.edu.tw

Recent studies have shown that reducing the crystal symmetry of substrate surfaces by surface atomic steps can lead to oriented seeding for the growth of single-crystal (SC) two-dimensional (2D) materials [1]. Au (111) surface is an ideal substrate for growing transition metal dichalcogenides (TMDs) but suffering from dewetting at high temperatures. In this report, we utilized ultra-high vacuum (UHV) e-gun evaporation followed by UHV sputtering to fabricate large-area SC Au (111) on an annealed sapphire surface. The Au (111) surface exhibited well-defined surface atomic steps after thermal treatments. Low-magnification electron backscatter diffraction (EBSD) and atomic force microscopy (AFM) confirm its SC structure with surface atomic steps. Unidirectional TMD grains can be grown on the Au (111) surface using chemical vapor deposition (CVD). Second-harmonic generation (SHG) mappings also confirm that the TMDs film has no grain boundaries. Scanning tunneling microscopy (STM) of TMDs directly grown on the Au (111) surface reveals a periodic moiré superstructure resulting from the lattice mismatch between TMDs and Au (111), indicating epitaxial growth [2].

[1] Yang, P., et al. Epitaxial growth of inch-scale single-crystal transition metal dichalcogenides through the patching of unidirectionally orientated ribbons. Nat Commun 2022, 13 (1), 3238.
[2] Yasuda, S., et al. Out-of-Plane Strain Induced in a Moire Superstructure of Monolayer MoS(2) and MoSe(2) on Au(111). Small 2017, 13 (31).

Keywords: two-dimensional materials, single crystal, atomic and nanoscale characterization, nanostructures, low-dimensional semiconductors