Surface asymmetry induced turn-overed lifetime of acoustic phonons in monolayer MoSSe
Xuefei Yan,
Xiangyue Cui,
Bowen Wang,
Hejin Yan,
Yongqing Cai,
Qingqing Ke
Affiliations
Xuefei Yan
School of Microelectronics Science and Technology, Sun Yat-Sen University, Zhuhai 519082, People’s Republic of China; Guangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems, Sun Yat-Sen University, Zhuhai 519082, People’s Republic of China; Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, People’s Republic of China
Xiangyue Cui
Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, People’s Republic of China
Bowen Wang
Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, People’s Republic of China
Hejin Yan
Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, People’s Republic of China
Yongqing Cai
Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, People’s Republic of China; Corresponding author
Qingqing Ke
School of Microelectronics Science and Technology, Sun Yat-Sen University, Zhuhai 519082, People’s Republic of China; Guangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems, Sun Yat-Sen University, Zhuhai 519082, People’s Republic of China; Corresponding author
Summary: Recent successful growth of asymmetric transition metal dichalcogenides via accurate manipulation of different chalcogen atoms in top and bottom surfaces demonstrates exotic electronic and chemical properties in such Janus systems. Within the framework of density functional perturbation theory, anharmonic phonon properties of monolayer Janus MoSSe sheet are explored. By considering three-phonons scattering, out-of-plane flexural acoustic (ZA) mode tends to undergo a stronger phonon scattering than transverse acoustic (TA) mode and the longitudinal acoustic (LA) mode with phonon lifetime of ZA (1.0 ps) < LA (23.8 ps) < TA (25.8 ps). This is sharply different from the symmetric MoS2 where flexural ZA mode has the weakest anharmonicity and is least scattered. Moreover, utilizing non-equilibrium Green function method, ballistic thermal conductance at room temperature is found to be around 0.11 nWK−1nm−2, lower than that of MoS2. Our work highlights intriguing phononic properties of such MoSSe Janus layers associated with asymmetric surfaces.
