Electronic structure and optical properties of CdTe rock‐salt high pressure phase
Electronic structure and optical properties of CdTe rock‐salt high pressure phase
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DOI：
10.1002/pssb.200301612
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发表时间：
2003-02
期刊：
影响因子：
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通讯作者：
H. S. Güder;S. Gilliland;J. Sans;A. Segura;J. González;I. Mora;V. Muñoz;A. Muñoz
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文献类型：
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作者：
H. S. Güder;S. Gilliland;J. Sans;A. Segura;J. González;I. Mora;V. Muñoz;A. Muñoz
本文报道了高达15gpa的CdTe薄样品的光学吸收和反射率测量。所有被研究的样品在锌-闪锌矿和岩盐相之间的压力转变（3.9 GPa）时几乎变得不透明。当压力增加到10 GPa时，在1.2 eV和2.4 eV之间形成一个相对透明区域，其高能边缘向更高的光子能量转移。在10 GPa以上，透明区逐渐缩小，在11 GPa左右消失。吸收光谱的低能侧归因于自由载流子吸收，因为电子结构计算表明岩盐CdTe是半金属或低间隙半导体。带填充效应降低了带对带的吸收系数，并产生了一个“透明”范围，根据其压力系数，其上能量侧分配给Γ点的直接跃迁。透明区域的缩小和消失，以及中红外反射率的大幅增加，可以解释为发生了向Cmcm金属相的相变。
This paper reports on optical absorption and reflectance measurements in thin CdTe samples up to 15 GPa. All studied samples become virtually opaque at the pressure transition between the zinc‐blende and rock‐salt phases (3.9 GPa). As pressure increases up to 10 GPa, a relative transparency region is observed between 1.2 eV and 2.4 eV, whose high energy edge shifts to higher photon energies. Above 10 GPa the transparency region gradually shrinks and disappears at about 11 GPa. The low energy side of the absorption spectrum is attributed to free carrier absorption, as electronic structure calculations show that rock‐salt CdTe is a semimetal or a low gap semiconductor. Band filling effects lower the band‐to‐band absorption coefficient and give rise to a “transparency” range, whose upper energy side is assigned to the direct transition at the Γ point, on the basis of its pressure coefficient. The shrinking and disappearance of the transparency region, along with a large increase of the reflectance in the mid infrared, is interpreted as the occurrence of a phase transition to the Cmcm metallic phase.