摘要:
采用磁控溅射法制备了Ge20Sb15Se65薄膜,研究热处理温度(150-400?C)对薄膜光学特性的影响.通过分光光度计、X射线衍射仪、显微拉曼光谱仪对热处理前后薄膜样品的光学特性和微观结构进行了表征,并根据Swanepoel方法以及Tauc公式分别计算了薄膜折射率色散曲线和光学带隙等参数.结果表明当退火温度(Ta)小于薄膜的玻璃转化温度(Tg)时,薄膜的光学带隙(Eoptg )随着退火温度的增加由1.845 eV上升至1.932 eV,而折射率由2.61降至2.54;当退火温度大于薄膜的玻璃转化温度时,薄膜的光学带隙随退火温度的增加由1.932 eV降至1.822 eV,折射率则由2.54增至2.71.最后利用Mott和Davis提出的非晶材料由非晶到晶态的结构转变模型对结果进行了解释,并通过薄膜XRD和Raman光谱进一步验证了结构变化是薄膜热致变化的重要原因.
Abstract:
The amorphous Ge20Sb15Se65 thin film was prepared by magnetron sputtering deposition technique. Effect of heat treatment temperature in the range of 150—400?C on the optical properties of Ge20Sb15Se65 thin films has been investigated. The microstructure and optical properties of the films were characterized by UV-Vis, Raman spectroscopy and XRD, the optical constant was calculated using the Swanepoel method and Tauc’s law from the optical transmission spectra. Results indicate that when the annealing temperature (Ta) is lower than the glass transition temperature (Tg), the optical band gap (Eoptg ) increases from 1.845 to 1.932 eV, and the refractive index decreases from 2.61 to 2.54, while the optical band gap decreases from 1.932 to 1.822 eV and the refractive index increases from 2.54 to 2.71 with a further increase of Ta. The results were explained in terms of the Mott and Davis model for amorphous materials and amorphous to crystalline structural transformations. It is well consistent with the results of structure analysis by XRD and Raman spectroscopy.
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