OPTICAL PROPERTIES OF MOTE2 AND WSE2
OPTICAL PROPERTIES OF MOTE2 AND WSE2
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DOI：
10.1002/pssa.2210130217
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发表时间：
1972-01-01
影响因子：
2
通讯作者：
EVANS, BL
中科院分区：
文献类型：
--
作者：
DAVEY, B;EVANS, BL
MoTe 2和WSe 2属于层状化合物MX2的类别，其晶体结构是由按XMX、XMX顺序的六方堆积原子片层堆叠而成。在每个XMX层内，每个M原子以三棱柱配位键合到六个最近的相邻X原子。由于一个层可以堆叠在另一个层上的各种方式，会出现许多堆叠多型体[1到3]。本文所研究的MoTe_2、WSe_2晶体具有2 H MoS_2晶体结构，其原子堆积顺序为（11.0）阿坝/BAB/阿坝。从气相直接生长的MoSe 2晶体[4]也具有2 H MoS 2结构，其通常被称为a-多型体。由于相邻X原子层之间的弱键合，许多MX 2六方层晶体允许沿沿着（00.1）容易分裂。通过反复劈裂，可以得到非常薄的晶体，然后可以通过测量光的透射率来确定其光学常数。这样的测量必须用垂直入射到解理晶体表面的光进行，即用光电矢量Ec，六方晶体（光学）轴。在0.5至3.5 eV范围内，介电常数的虚部e2的光谱变化先前已被确定为同构化合物钙钛矿[5，6]和a-MoSe 2 [4];对MoTe 2，WSe 2进行本发明的测量是为了确定在MoS 2，MoSe 2，MoTe 2以及在MoSe 2中用W取代Mo的后果。
MoTe2 and WSe2 belong to the class of layer-like compounds MX2 whose crystal structure results from the stacking of sheets of hexagonally packed atoms in the sequence XMX, XMX. Within each XMX layer each M atom is bonded to six nearest neighbour X atoms in trigonal prism co-ordination. A number of stacking polytypes occur as a result of the various ways in which one layer can be stacked upon another [1 to 3]. The MoTe2, WSe2 crystals considered here have the 2H MoS2 crystal structure which has the (11.0) atomic stacking sequence ABA/BAB/ABA. Crystals of MoSe2 grown directly from the vapour phase [4] also have the 2H MoS2 structure which is often referred to as the a-polytype.Many of the MX2 hexagonal layer crystals allow easy cleavage along (00.1) as a result of the weak bonding between adjacent sheets of X atoms. By repeated cleaving very thin crystals can be obtained whose optical constants can then be determined from measurements of the light transmissivity. Such measurements are necessarily made with light at normal incidence to the cleaved crystal surface, ie with the light electric vector E c, the hexagonal crystal (optic) axis. The spectral variation of e2, the imaginary part of the dielectric constant, over the range 0.5 to 3.5 eV has previously been determined for the isostructural compounds molybdenite [5, 6] and a-MoSe2 [4]; the present measurements on MoTe2, WSe2 were made in order to determine any systematic change that may occur in the sequence MoS2, MoSe2, MoTe2 and also the consequences of replacing Mo by W in MoSe2.