Anisotropic optical constants and inter-band optical transitions in layered semiconductor TlGaSe2
Anisotropic optical constants and inter-band optical transitions in layered semiconductor TlGaSe2
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层状半导体 TlGaSe2 中的各向异性光学常数和带间光学跃迁
DOI：
10.1016/j.apsusc.2016.11.005
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发表时间：
2016
影响因子：
6.7
通讯作者：
N. Mamedov
中科院分区：
文献类型：
--
作者：
Y. Shim;Y. Itoh;K. Wakita;N. Mamedov
在80 - 400 K温度范围内，研究了具有准二维层状结构的TlGaSe_2晶体在1.5 - 5.0 eV光子范围内的介电函数谱。通过光谱椭圆偏振法访问（100）和（001）表面，并在对椭圆偏振数据进行常规处理后检索介电函数。通过使用标准临界点分析确定与所获得的介电函数相关联的带间光学跃迁。在计算的电子能带结构的框架内完成的过渡分配。在104.5，123.3和247.0K，获得了由温度引起的铊轨道参与形成的电子态之间带间光跃迁临界点能量的突变。最后的温度与TlGaSe 2中随后的结构相变的温度点一致。
The dielectric function spectra of TlGaSe2crystal with quasi-two-dimensional layered structure were studied over the photon range 1.5–5.0 eV in the temperature range 80–400 K. The (100) and (001) surfaces were accessed by spectroscopic ellipsometry and the dielectric function was retrieved after conventional treatment of the ellipsometric data. Inter-band optical transitions associated with the obtained dielectric function were determined by using standard critical point analysis. Assignment of the transitions was done within the framework of the calculated electronic band structure. An abrupt temperature-induced change in energy of the retrieved critical points for inter-band optical transitions between the electronic states formed with participation of thallium orbitals was obtained at 104.5, 123.3 and 247.0 K. The last temperatures agree well with the temperature points of the subsequent structural phase transitions in TlGaSe2.