Optical spectra and electronic structure of crystalline and glassy Ge(S,Se)2
Optical spectra and electronic structure of crystalline and glassy Ge(S,Se)2
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DOI：
10.1103/physrevb.23.816
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发表时间：
1981-01
影响因子：
3.7
通讯作者：
D. Aspnes;J. C. Phillips;K. Tai;P. Bridenbaugh
中科院分区：
文献类型：
--
作者：
D. Aspnes;J. C. Phillips;K. Tai;P. Bridenbaugh
报道了蒸发（g-）锗硒2膜、（c-）锗硒2单晶和蒸发掺银光活化锗硒2膜的介电函数谱在1.5 ~ 5.8 eV之间。c-Ge - Se- 2是二向色的，产生两个光谱，我们将其与材料中的介电张量平行和垂直于gese链的分量联系起来。g-Ge Se 2的介电函数有两个宽峰，与c-Ge Se 2的谱线非常相似。除了精细结构外，g-Ge - Se - 2光谱可以在有效介质近似下由c-Ge - Se - 2光谱合成。所有结构都用一个简单的模型来描述，该模型由两个狭窄的（~ 1 eV）价带和一个较低的传导带组成。掺银薄膜的光谱在ε 2中只有一个宽峰。这些结果表明g-Ge Se 2中存在中等范围的有序，这与最近的一个理论相一致，该理论认为玻璃的有序程度比基于“随机”网络模型的普遍预期要高得多。
Dielectric-function spectra from 1.5 to 5.8 eV are reported for evaporated (g-) Ge Se 2 films,(c-) Ge Se 2 single crystals, and evaporated Ag-doped photoactivated Ge Se 2 films. c-Ge Se 2 is dichroic, yielding two spectra that we relate to the components of the dielectric tensor parallel and perpendicular to the-GeSe-chains in this material. The dielectric function of g-Ge Se 2 shows two broad peaks, which closely resemble the c-Ge Se 2 spectra. Except for fine structure, the g-Ge Se 2 spectrum can be synthesized from the c-Ge Se 2 spectra in the effective-medium approximation. All structures are described by a simple model consisting of two narrow (∼ 1 eV) valence bands and a lower conduction band. Spectra for Ag-doped films have only a single broad peak in ε 2. These results point to the existence of medium-range order in g-Ge Se 2, in agreement with a recent theory which ascribes much greater order to the glass than is commonly expected on the basis of" random" network models.