In-Plane Anisotropies of Polarized Raman Response and Electrical Conductivity in Layered Tin Selenide.
The group IV-VI compound tin selenide (SnSe) has recently attracted particular interest due to its unexpectedly low thermal conductivity and high power factor and shows great promise for thermoelectric applications. With an orthorhombic lattice structure, SnSe displays intriguing anisotropic properties due to the low symmetry of the puckered in-plane lattice structure. When thermoelectric materials, such as SnSe, have decreased dimensionality, their thermoelectric conversion efficiency may be improved due to increased power factor and decreased thermal conductivity. Therefore, it is necessary to elucidate the complete optical and electrical anisotropies of SnSe nanostructures in realizing the material's advantages in high-performance devices. Here, we synthesize single-crystal SnSe nanoplates (NPs) using the chemical vapor deposition method. The SnSe NPs' polarized Raman spectra exhibit an angular dependence that reveals the crystal's anomalous anisotropic light-matter interaction. The Raman's anisotropic response has a dependence upon the incident light polarization, photon, and phonon energy, arising from the anisotropic electron-photon and electron-phonon interactions in the SnSe NPs. Finally, angle-resolved charge-transport measurements indicate strong anisotropic conductivity of the SnSe NPs, fully elucidating the anisotropic properties necessary for ultrathin SnSe in electronic, thermoelectric, and optoelectronic devices.
State Key Lab for Mesoscopic Physics and School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100871, China.
Xiaolong
X
Xu
State Key Lab for Mesoscopic Physics and School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100871, China.
Qingjun
Q
Song
National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China.|Department of Physics, College of Science, Shihezi University , Xinjiang 832003, China.
Haifeng
H
Wang
State Key Lab for Mesoscopic Physics and School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100871, China.
Pan
P
Li
State Key Lab for Mesoscopic Physics and School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100871, China.
Kun
K
Zhang
State Key Lab for Mesoscopic Physics and School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100871, China.
Yilun
Y
Wang
State Key Lab for Mesoscopic Physics and School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100871, China.
Kai
K
Yuan
State Key Lab for Mesoscopic Physics and School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100871, China.
Zichen
Z
Yang
State Key Lab for Mesoscopic Physics and School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100871, China.
Yu
http://orcid.org/0000-0001-6046-063X
Y
Ye
State Key Lab for Mesoscopic Physics and School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter , Beijing 100871, China.
Lun
http://orcid.org/0000-0002-6317-6340
L
Dai
SnSe nanoplate; anisotropic charge transport; electron−phonon coupling; layered materials; polarized Raman spectra