基片温度对PLD制备ZnO薄膜光学常数的影响

光谱椭偏仪被用来研究用脉冲激光沉积方法在Si(100)基片上,温度分别为400,500,600,700 ℃制备的ZnO薄膜的特性。利用三层Cauchy散射模型拟合椭偏参数,计算了每个温度下制备的ZnO薄膜在400~800 nm波长范围内的折射率(n)和消光系数(k)。发现基片温度对光学常数有很大的影响。通过分析XRD表征的晶体结构和 AFM表征的薄膜表面形貌,发现折射率的变化归因于薄膜堆积密度的变化。为了获得具有较好的光学和薄膜质量的ZnO薄膜,相比与其他沉积温度600 ℃或许是最佳的沉积温度。

Influence of Substrate Temperature on the Optical Constants of ZnO Thin Film Grown by PLD

Spectroscopic ellipsometry(SE) was employed to characterize ZnO thin films prepared by pulsed laser deposition (PLD) on Si (100) substrates at various temperature of 400, 500, 600 and 700 ℃. The refractive indices (n) and extinction coefficients (k) of the ZnO films were calculated in the spectral range of 400～800 nm for each deposition temperature by fitting the ellipsometic parameters based on a three-layers dispersion with Cauchy model. It was found that the optical constants were significantly affected by the substrate temperature. Through analyzing the crystalline structures and surface morphologies of ZnO thin films grown at different substrate temperature by XRD and atomic force microscopy (AFM), respectively, the variation of the refractive index can be attributed to the changes of the packing density of the thin film. After comparing the results obtained at different grown temperature, it was suggested 600 ℃ might be the optimum deposition temperature for growing dense ZnO films with high optical and crystalline quality.