Abstract

In the UV-visible-near infrared regions from 245 to 1000 nm, variable-angle spectroscopic ellipsometer (VASE) was used to investigate optical functions of As₂S₃ and As₂Se₃ thin films. In the entire measured spectral range, data were analyzed by assembly from several dispersion models. These assemblies comprise individual Tauc–Lorentz supplemented by several Lorentz (TL-group) or single Cody–Lorentz with several Lorentz (CL-group) models. For As₂S₃ and As₂Se₃ thin films, the optical parameters were quantified. The model parameters, such as the Lorentz amplitude, resonance frequency, oscillator width, extinction coefficients, refractive indices, and Urbach and optical band energy of both films were obtained. The band gap energy E_g was experimentally determined using the obtained data of CL-group from (αhν)^1/2 vs. hν plots. It is found that the band gap energies of As₂Se₃ and As₂S₃ were 1.796 and 2.349 eV, respectively. The E_g values for the films were theoretically investigated by the bond statistics of the random covalent network model (CRNM) with the aid of Manca’s relation. Plausible agreement between the experimental and calculated E_g values for both samples was obtained.

中文翻译：

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可变角度光谱椭圆仪测量紫外到近红外的As 2 S 3和As 2 Se 3薄膜的光学参数

摘要

在245-1000 nm的紫外-可见-近红外区域，使用可变角度光谱椭圆仪（VASE）研究As ₂ S ₃和As ₂ Se ₃薄膜的光学功能。在整个测得的光谱范围内，通过组装来自多个色散模型的数据进行了分析。这些组件包括单独的Tauc-Lorentz（补充有多个Lorentz（TL组））或单个Cody-Lorentz（具有多个Lorentz（CL组）模型）。对于As ₂ S ₃和As ₂ Se ₃薄膜，光学参数被量化。获得了两个膜的模型参数，例如洛伦兹振幅，共振频率，振荡器宽度，消光系数，折射率和Urbach以及光带能量。带隙能量Ë_克使用从（α所获得的CL-组的数据被实验确定ħ ν）^1/2与ħ ν图。发现As ₂ Se ₃和As ₂ S ₃的带隙能分别为1.796和2.349 eV。该ë _{g ^}通过Manca的关系，通过随机共价网络模型（CRNM）的键统计，从理论上研究了膜的值。获得了两个样品的实验Eg值和计算得出的E _g值之间的合理一致性。