Effects of pressure and temperature on the dielectric constant of GaS, GaSe, and InSe:: Role of the electronic contribution
Effects of pressure and temperature on the dielectric constant of GaS, GaSe, and InSe:: Role of the electronic contribution
复制标题
DOI：
10.1103/physrevb.60.15866
复制
发表时间：
1999-12-15
影响因子：
3.7
通讯作者：
Chevy, A
中科院分区：
文献类型：
--
作者：
Errandonea, D;Segura, A;Chevy, A
在这项工作中，我们报告了沿 GaS、GaSe 和 InSe 的 c 轴（ε（平行于））的低频介电常数的温度和压力依赖性的直接测量。还给出了寻常折射率和非常折射率的温度依赖性。已观察到在压力下 epsilon（平行）大幅增加。在刚性离子模型的框架中，由于阴离子-阳离子键与层平面之间的角度发生变化，在压力下，晶格对ε（平行）的贡献略有增加。因此，ε（平行于）的压力行为被认为是由于电子对ε（平行于）的贡献大幅增加而产生的。这一事实可以通过平行于 c 轴的偏振的佩恩带隙的减小来解释，其能量和压力系数与这些化合物中的间接带隙的能量和压力系数成比例。在 GaS 中，在 1.6 GPa 时观察到 epsilon（平行于）的补充且可逆的阶跃增加，这与其他作者已经观察到的相变相关。 [S0163-1829(99)11547-9]。
In this work we report on direct measurements of the temperature and pressure dependences of the low-frequency dielectric constant along c axis (epsilon(parallel to)) of GaS, GaSe, and InSe. The temperature dependence of both the ordinary and extraordinary refractive indexes is also presented. A large increase of epsilon(parallel to) under pressure has been observed. In the framework of a rigid ion model, the lattice contribution to epsilon(parallel to) is shown to increase slightly under pressure, due to the change of the angle between the anion-cation bond and the layer plane. Consequently, the pressure behavior of epsilon(parallel to) is proposed to arise from a large increase of the electronic contribution to epsilon(parallel to). This fact is explained through a decrease of the Penn gap for polarization parallel to the c axis, whose energy and pressure coefficient are shown to scale with those of the indirect band gap in these compounds. A supplementary and reversible step increase of epsilon(parallel to) is observed at 1.6 GPa in GaS, which is associated with a phase transition that has been already observed by other authors. [S0163-1829(99)11547-9].