酞菁氧钛薄膜光学常数的测量研究

Study on optical properties of oxotitanium phthalocyanine

使用M-2000UI型宽光谱可变入射角椭偏仪,对在单晶硅片上真空蒸镀的酞菁氧钛(TiOPc)薄膜的光学性质进行了研究。在248～1650nm(0.75～5ev)的范围内分别使用柯西模型、逐点拟合模型、洛伦兹模型和高斯模型对测得的椭偏光谱进行拟合分析,获得了TiOPc薄膜的折射率、消光系数和复介电常数。通过比较,我们发现高斯模型拟合的均方差较小,拟合数据和测试数据重合度好,而且拟合得到的光学常数的图线光滑连续,因此认为高斯模型最适用于描述TiOPc薄膜的光学性质。由高斯模型拟合所得的消光系数推出了TiOPc薄膜的吸收谱,结果发现TiOPc薄膜在紫外可见近红外区有一系列的吸收峰,分析了其电子结构及吸收谱成因,并由吸收谱推算了其光学禁带宽度。

The optical properties of oxotitanium phthalocyanine（TiOPc） thin film are studied by spectroscopic ellipsometry u sing a variable angle spectrometric ellipsometer. TiOPc thin film is prepared by vacuum deposition on a silicon substrate. Spectroscopic ellipsometry measurements are performed at different angles of incidence （55°,60°,65° and 70°） in the wave length range of 248 nm-1650 nm （0.75 ev-5 ev）. The analysis shows that compared with the Cauchy model, point-by point fitting,and the Lorentz model the Gaussian model is more suitable for description of the optical functions of TiOPc. The absorption coefficient of TiOPc film can be obtained from extinction coefficient. It is revealed that there are several large ab sorption peaks in the measurement range. The spectrum is explained with its energy levels structure. The optical band gap （Eg） is also derived from the edge of the absorption.