Characterization of thin Bi2Te3-based films and effects of heat treatment on their optical properties
Characterization of thin Bi2Te3-based films and effects of heat treatment on their optical properties
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Bi2Te3 基薄膜的表征以及热处理对其光学性能的影响
DOI：
10.1016/j.jallcom.2018.06.159
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发表时间：
2018
影响因子：
6.2
通讯作者：
A. Adam
中科院分区：
文献类型：
--
作者：
A. Adam
Bi2Te3 和基于 Bi2Te3 的薄膜在高真空下热蒸发到高度清洁的玻璃基板上。源材料是通过标准熔化方法制备的块状合金。沉积薄膜的 X 射线衍射分析表明其具有六方型结构的多晶性质。分别通过AFM和SEM研究表面粗糙度和形貌。 TEM 研究证实了相关材料的纳米结晶性。定义了合成薄膜在 300°C 空气气氛中退火 3 小时之前和之后的光学特性。使用双光束分光光度计在 350-2700 nm 波长范围内测量制备和退火薄膜的透射率和反射率光谱。根据测量的光谱和薄膜的厚度得出吸收系数、折射率和能带隙值。研究发现Bi2Te3基材料是高折射率材料。折射率用于使用 Wemple-DiDomenico 方法根据单振荡器常数计算和确定光色散能量。所允许的光学跃迁被观察为直接光学跃迁，能隙在 0.56-0.82eV 范围内。在退火处理之前和之后估计光学介电函数的实部和虚部，显示出非常高的值。退火后检测到进一步增加。研究了热退火对含 Bi2Te3 和 Se 薄膜光学性能的影响，并与本工作中制备的相应样品进行了比较。
Thin Bi2Te3and based films were thermally evaporated onto highly cleaned glass substrate at high vacuum. Source materials are bulk alloys prepared by the standard melting method. X-ray diffraction analysis of the as-deposited films asserted a polycrystalline nature with a hexagonal type structure. Surface roughness and morphology were investigated by means of AFM and SEM respectively. Nano-crystallinity of the concerned materials was asserted by TEM investigations. Optical characteristics were defined for the synthesized films before and after annealing in air atmosphere for 3 h at 300 °C. Transmittance and reflectance spectra of the as prepared and annealed films were measured in the wavelength range 350–2700 nm using a double beam spectrophotometer. Absorption coefficient, refractive index and energy band gap values were derived based on the measured spectra and the film's thickness. It was found that Bi2Te3-based materials are highly refractive indexed material. Index of refraction was used for calculation and determination of optical dispersion energies, in terms of the single oscillator constants using the Wemple–DiDomenico method. The allowed optical transitions were observed as direct optical transitions with energy gap in the range of 0.56–0.82 eV. Real and imaginary parts of the optical dielectric function were estimated before and after annealing treatment, exhibiting very high values. Further increase was detected after annealing. The influence of thermal annealing on the optical properties of the Bi2Te3and Se containing films is investigated and compared to the as-prepared corresponding samples in the present work.
影响因子：
38.3
作者：
Hernandez, Yenny;Nicolosi, Valeria;Coleman, Jonathan N.
通讯作者：
Coleman, Jonathan N.