Supercell structures of monolayer PtSe2 on Au Substrates

Guan-Hao Chen^1*, Han Yeh¹, Juhn-Jong Lin², Chun-Liang Lin¹, Wen-Hao Chang^1,3

¹Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
²Institute of physics, National Chiao Tung University, Hsinchu, Taiwan
³Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:Guan-Hao Chen, email:a0913635603.ep06g@nctu.edu.tw

Platinum diselenide (PtSe2) belongs to the family of transition metal dichalcogenides (TMDs). Although bulk PtSe2 crystal is a semimetal, monolayer PtSe2 has been experimentally verified as a semiconductor with a bandgap of ~1.2 eV. Monolayer PtSe2 has also been theoretically predicted to exhibit the highest carrier mobility among various TMDs. Moreover, the local Rashba effect in monolayer PtSe2 can induce the helical spin texture with spin-layer locking. These unique properties make monolayer PtSe2 become a promising material for high-speed electronic and spintronic devices. Therefore, epitaxial growth of high-quality monolayer PtSe2 films on a suitable substrate is a critical step toward this goal. In this work, we present scanning tunneling microscopy/spectroscopy (STM/S) studies of PtSe2 grown on Au substrates by chemical vapor deposition. Our STM studies reveals two kinds of periodic lattices. One is the atomic lattice of PtSe2 with rhombus unit cell. The other shows rectangular supercells originating from the commensurate stacking of PtSe2 on Au substrate. The two side lengths of the supercell are 1.15 and 1.27 nm along the zigzag and the armchair direction, respectively. Although STS result shows that PtSe2 is metallic behavior on Au substrate, the unique commensurate stacking between monolayer PtSe2 and Au substrate provides an opportunity to grow wafer-scale and single-domain monolayer PtSe2.

Keywords: Platinum diselenide, scanning tunneling microscopy, Commensurate stacking