Strong interlayer coupling and layer-dependent bandgap in 2D layered PdSe<sub>2</sub> synthesized by chemical vapor deposition

ORAL

Abstract

Two-dimensional (2D) noble metal dichalcogenides, such as PtS2 or PdSe2, have attracted much attention due to their remarkable layer-dependent electronic structures and superior electrical properties for device applications. However, most of the demonstrated experiments thus far are based on mechanical exfoliations from bulk crystals. Here, we demonstrate that highly crystalline and air stable PdSe2, from bilayer up to few layers, can be synthesized by chemical vapor deposition. The atomic ratio and the lattice structure of PdSe2 have been confirmed by x-ray photoemission and polarization-resolved Raman spectra. Low-frequency Raman measurements of breathing vibration modes reveal the strong interlayer coupling, which can also be used for identifying the layer numbers [1]. Based on absorption measurements, we observed a strongly layer-dependent bandgap, which shows a gap shrinkage up to 0.5 eV with the increasing layer number from bilayer to 7 layers. The dramatically layer-dependent bandgap shrinkage is also consistent with the calculated energy gap based on density functional theory.[2]

[1] Puretzky A.A., et al., 2D Materials, 5(3), p. 035016, 2018.
[2] Oyedele A.D., et al., J Am Chem Soc, 139(40), p. 14090-14097, 2017.

–

Presenters

  • Li-Syuan Lu

    • Department of Electrophysics, National Chiao Tung University,

Authors

  • Li-Syuan Lu

    • Department of Electrophysics, National Chiao Tung University,

  • Hui-Yu Cheng

    • Department of Electrophysics, National Chiao Tung University,
    • Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan

  • Guan-Hao Chen

    • Department of Electrophysics, National Chiao Tung University,

  • Chia-Hao Chen

    • National Synchrotron Radiation Research Center (NSRRC)

  • Tzu-Hung Chuang

    • National Synchrotron Radiation Research Center (NSRRC)

  • Der-Hsin Wei

    • National Synchrotron Radiation Research Center (NSRRC)

  • Ming-Yang Li

    • Physical Sciences and Engineering, King Abdullah University of Science and Technology
    • Corporate Research and Chief Technology Office, Taiwan Semiconductor Manufacturing Company (TSMC)

  • Chih-Piao Chuu

    • Corporate Research and Chief Technology Office, Taiwan Semiconductor Manufacturing Company (TSMC)

  • Lain-Jong Li

    • Corporate Research and Chief Technology Office, Taiwan Semiconductor Manufacturing Company (TSMC)

  • Wen-Hao Chang

    • Electrophysics, National Chiao Tung University
    • Department of Electrophysics, National Chiao Tung University
    • Department of Electrophysics, National Chiao Tung University,
    • Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan
    • Department of Electrophysics, National Chiao Tung University, Taiwan