基于反应磁控溅射Al2O3薄膜的紫外—可见—近红外透射实验光谱,采用Swanepoel方法结合Wemple-DiDomenico色散模型,方便地导出了Al2O3薄膜在200—1100nm波长范围内的光学常数,包括折射率、色散常数、膜层厚度、吸收系数及能量带隙.研究发现反应磁控溅射Al2O3薄膜具有高折射率(1.556—1.76,测试波长为550nm)、低吸收和直接能量带隙(3.91—4.20eV)等光学特性,而且其光学常数对薄膜制备过程中的重要工艺参数——膜层后处理温度表现出强烈的依赖性.此外,在膜层的弱吸收和中等吸收光谱区域内,计算得到的折射率色散曲线与分光光度法的测试结果基本符合,说明本实验中所建立的计算方法在确定反应磁控溅射Al2O3薄膜光学常数方面的可靠性.
By combining Swanepoel′s theory and the Wemple-DiDomenico dispersion model,a simple method was established to determine the optical contants of the magnetron sputtered aluminum oxide films directly from the corresponding transmission spectra. The results showed that the magnetron sputtered aluminum oxide films exhibit the optical characteristics of high refractive index of 1. 566—1. 76 ( at 550 nm),negligible absorption in spectral region of 400— 1100 nm,as well as the direct band gap of about 3. 91—4. 2 eV. And the specific values of the optical constants strongly depend on the annealing temperature ,which is one of the important technological parameters for the magnetron sputtered aluminum oxide films. Moreover,in the weak and medium absorption spectral regions,the calculated values of refractive indices are in satisfactory agreement with the results derived from the high-resolution Tek3000 film-characterization system,indicating the reliability and feasibility of the method in determining the optical constants of Al2O3films.