Two-dimensional (2D) transition-metal dichalcogenides (2D TMDs) in the form of MX 2 (M: transition metal, X: chalcogen) exhibit intrinsically anisotropic layered crystallinity wherein their material properties are determined by constituting M and X elements. 2D platinum diselenide (2D PtSe 2 ) is a relatively unexplored class of 2D TMDs with noble-metal Pt as M, offering distinct advantages over conventional 2D TMDs such as higher carrier mobility and lower growth temperatures. Despite the projected promise, much of its fundamental structural and electrical properties and their interrelation have not been clarified, and so its full technological potential remains mostly unexplored. In this work, we investigate the structural evolution of large-area chemical vapor deposition (CVD)-grown 2D PtSe 2 layers of tailored morphology and clarify its influence on resulting electrical properties. Specifically, we unveil the coupled transition of structural-electrical properties in 2D PtSe 2 layers grown at a low temperature (i.e., 400 °C). The layer orientation of 2D PtSe 2 grown by the CVD selenization of seed Pt films exhibits horizontal-to-vertical transition with increasing Pt thickness. While vertically aligned 2D PtSe 2 layers present metallic transports, field-effect-transistor gate responses were observed with thin horizontally aligned 2D PtSe 2 layers prepared with Pt of small thickness. Density functional theory calculation identifies the electronic structures of 2D PtSe 2 layers undergoing the transition of horizontal-to-vertical layer orientation, further confirming the presence of this uniquely coupled structural-electrical transition. The advantage of low-temperature growth was further demonstrated by directly growing 2D PtSe 2 layers of controlled orientation on polyimide polymeric substrates and fabricating their Kirigami structures, further strengthening the application potential of this material. Discussions on the growth mechanism behind the horizontal-to-vertical 2D layer transition are also presented.
Bibliographical noteFunding Information:
Y.J. acknowledges financial support from the University of Central Flordida (grant no. 20080742). This research was supported by Creative Materials Discovery Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (NRF-2017M3D1A1039553) and by the National Research Foundation of Korea (grant no. NRF-2018R1D1A1B07043973). The work at Yonsei is supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017R1A2B2006568, 2017R1A5A1014862, SRC program: vdWMRC center), and the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (no. 20173010013340). S.S.H. and K.H.O. were supported by a grant [KCG-01-2017-02] through the Disaster and Safety Management Institute funded by Korea Coast Guard of Korean government.
Copyright © 2019 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Materials Science(all)