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Anisotropic Phonon Response of Few‐Layer PdSe 2 under Uniaxial Strain
Author(s) -
Luo Weijun,
Oyedele Akinola D.,
Gu Yiyi,
Li Tianshu,
Wang Xingzhi,
Haglund Amanda V.,
Mandrus David,
Puretzky Alexander A.,
Xiao Kai,
Liang Liangbo,
Ling Xi
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202003215
Subject(s) - materials science , phonon , raman spectroscopy , anisotropy , condensed matter physics , strain (injury) , strain engineering , crystal (programming language) , layer (electronics) , poisson's ratio , perpendicular , optics , nanotechnology , optoelectronics , poisson distribution , geometry , physics , medicine , mathematics , computer science , programming language , statistics , silicon
Abstract PdSe 2 , an emerging 2D material with a novel anisotropic puckered pentagonal structure, has attracted growing interest due to its layer‐dependent electronic bandgap, high carrier mobility, and good air stability. Herein, a detailed Raman spectroscopic study of few‐layer PdSe 2 (two to five layers) under the in‐plane uniaxial tensile strain up to 3.33% is performed. Two of the prominent PdSe 2 Raman peaks are influenced differently depending on the direction of strain application. TheA g 1mode redshifts more than theA g 3mode when the strain is applied along the a ‐axis of the crystal, while theA g 3mode redshifts more than theA g 1mode when the strain is applied along the b ‐axis. Such an anisotropic phonon response to strain indicates directionally dependent mechanical and thermal properties of PdSe 2 and also allows the identification of the crystal axes. The results are further supported using first‐principles density‐functional theory. Interestingly, the near‐zero Poisson’s ratios for few‐layer PdSe 2 are found, suggesting that the uniaxial tensile strain can easily be applied to few‐layer PdSe 2 without significantly altering their dimensions at the perpendicular directions, which is a major contributing factor to the observed distinct phonon behavior. The findings pave the way for further development of 2D PdSe 2 ‐based flexible electronics.