氧化铟锡薄膜的椭偏光谱研究

用溅射法在Si片上制备了厚度为140nm的氧化铟锡(ITO)薄膜。X射线衍射研究表明所制备的薄膜为多晶结构。在1.5~4.5eV范围内对ITO薄膜进行了椭偏测量。分别用德鲁德-洛伦茨谐振子(Drude Lorenz oscillators)模型、层进模型结合有效介质近似模型对椭偏参量ψ、Δ进行了拟合,得到ITO薄膜的折射指数n的变化范围在1.8~2.6之间,可见光范围内消光系数k接近于零,在350nm波长附近开始明显变化,且随着波长的减小k迅速增加。计算得到直接和间接光学带隙分别是3.8eV和4.2eV。并在1.5~4.5eV段给出一套较为可靠的、具有实用价值的ITO介电常量和光学常量。

Study on Ellipsometric Spectra of ITO Film

Indium tin oxide(ITO)film with thickness of 140 nm was grown on Si substrate by sputtering method.X-ray diffraction(XRD)analysis shows that the film has the polycrystal structrue.The film was studied with reflecting spectroscopic ellipsometry in the energy range 1.5-4.5 eV.Parameterized analyses,based on Lorenz oscillators combined with Drude model,Graded model associated with Bruggeman effective-medium approximation model,were used to determine the optical constants and the thickness of the thin film.The results show that the indices of refraction of ITO film are in the range of 1.8-2.6 and the extinction coefficients are close to zero in the visible range and increase sharply near the wavelength of 350 nm.The optical band gap of the ITO film was estimated.A set of applicable and valuable data of dielectric coefficients and optical constants of the film were listed.