中文摘要：

射频磁控溅射法制备 a-Si：H 薄膜，利用椭圆偏振光谱对不同气压下 a-Si：H 薄膜的厚度、折射率和消光系数进行了测试和研究。薄膜采用双层光学模型，通过 Forouhi-Bloomer 模型对椭圆偏振光谱参数进行拟合，获得450-850 nm 光谱区域的 a-Si：H 薄膜光学参数值。结果表明，随着工作气压增加，薄膜厚度增厚，沉积速率升高；相同工作气压下，随偏振光波长增大，折射率呈下降趋势；相同波长偏振光下，折射率随工作气压上升而下降，折射率变化范围在3.5-4.1；消光系数随着工作气压增大呈略微增大的趋势。根据吸收系数与消光系数的关系，获得了薄膜的吸收谱，测算出不同工作气压下 a-Si：H 薄膜的光学带隙为1.63 eV-1.77 eV。

英文摘要：

High quality a-Si：H thin films were prepared by RF magnetron sputtering.Thickness,refractive index and extinction coefficient of the a-Si：H thin films with different working gas pressure were tested and studied by spectroscopic ellipsometry , respectively.Double optical model of a-Si：H thin film was used in the analysis.Optical parameters between 450~850 nm were obtained by fitting through Forouhi-Bloomer model.Results show that the thickness of the a-Si：H thin film increases with working gas pressure increasing.Under certain working gas pressure,refractive index decreases with the increase of incident wavelength.Under fixed incident wavelength,refractive index in the range of 3.5~4.1 decreases and extinction coefficient increases slowly with working gas pressure increasing.Absorption spectrum was obtained based on the relation of absorptivity and extinction coefficient.The optical band gap of 1.63-1.77 eV for the a-Si：H thin film was calculated with the absorption spectrum.