In-plane anisotropy of the optical and electrical properties of ReS2 and ReSe2 layered crystals
In-plane anisotropy of the optical and electrical properties of ReS2 and ReSe2 layered crystals
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DOI：
10.1016/s0925-8388(00)01332-3
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发表时间：
2001-04-12
影响因子：
6.2
通讯作者：
Tiong, KK
中科院分区：
文献类型：
--
作者：
Ho, CH;Huang, YS;Tiong, KK
ReS_2和ReSe_2属于三斜对称的扭曲八面体晶层结构的过渡金属二盐化合物家族。具有三斜对称的晶体在光学上是双轴的。对于垂直于基面入射的线偏振光，ReS2和ReSe2的带间跃迁有望表现出各向异性。通过偏振相关的压阻反射(PZR)和光学吸收测量，研究了E平行TOB和E垂直TOB偏振的光学各向异性效应。PzR谱的偏振相关性提供了确凿的证据，表明与带间激子跃迁相关的特征来自不同的来源。吸收测量结果表明，ReS_2和ReSe_2是间接半导体，E平行于b轴偏振呈现出较小的带隙，单声子对间接跃迁有重要的辅助作用。两种晶体沿b轴方向的电导率均比垂直于b轴方向的电导率高出数倍。(C)2001 Elsevier Science B.V.：保留所有权利。
ReS2 and ReSe2 belong to the family of transition-metal dichalcogenides crystallized in the distorted octahedral layer structure of triclinic symmetry. Crystals with triclinic symmetry are optically biaxial. The interband transitions of ReS2 and ReSe2 are expected to chow anisotropic character for linearly polarized light, incident normal to the basal plane. The optical anisotropic effects for E parallel tob and E perpendicular tob polarizations were studied through polarization-dependent piezoreflectance (PzR) and optical :absorption measurements. The polarization dependence of the PzR spectra provides conclusive evidence that the features associated with the interband excitonic transitions are originated from different origins. The results of absorption measurements indicate that ReS2 and ReSe2 are indirect semiconductors, in which E parallel to b-axis polarization exhibits a smaller band gap and a single phonon makes an important contribution in assisting the indirect transitions. The electrical conductivity along the b-axis was shown to be several times higher than that perpendicular to b-axis for both crystals. (C) 2001 Elsevier Science B.V: All rights reserved.