两种Ge-Sb-Se薄膜的光学性质及微观结构

提出一种综合利用区域逼近法和柯西拟合法精确获取Ge28Sb12Se60薄膜和Ge28Sb12Se60薄膜透射光谱范围内任意波长处折射率与色散的多点柯西法,并从理论上证明了该方法的准确性.实验上,采用磁控溅射法制备了这两种Ge-Sb-Se薄膜,利用傅里叶红外光谱仪测得了透射光谱曲线,运用分段滤波的方法去除噪声,然后使用多点柯西法得到了这两种薄膜在500-2500 nm波段的折射率、色散、吸收系数和光学带隙.结果表明Ge28Sb12Se60薄膜的折射率和吸收系数大于Ge28Sb15Se65薄膜, Ge28Sb15Se65薄膜的光学带隙小于Ge28Sb12Se60薄膜.最后,利用拉曼光谱对两种薄膜的微观结构进行了表征,从原子之间的键合性质解释了这两种硫系薄膜不同光学性质的原因.

Optical properties and microstructure of two Ge-Sb-Se thin films

Multipoint Cauchy method(MCM)is presented to investigate the refractive index and dispersion for each of Ge20Sb15Se65 and Ge28Sb12Se60 chalcogenide thin films at any wavelength in the transmission spectrum based on the regional approach method and Cauchy fitting.We theoretically calculate and compare the refractive index and dispersion curves obtained by using six different models.The results show that the most accurate results are obtained by the MCM.Two Ge—Sb—Se films are prepared by magnetron sputtering experimentally,and transmission spectrum curves are measured by Fourier infrared spectrometer,the noise is removed by segmental filtering and then the refractive index,dispersion,absorption coefficient,and optical band gap of the two films ina range of 500–2500 nm are obtained by the MCM.The results show that the refractive index of Ge28Sb12Se60 film is larger than that of Ge20Sb15Se65 film,which is caused by the higher polarizability and density of the former.The refractive indexes of both films decrease with wavelength increasing,so the long waves travel faster than short waves in the two films.The optical band gap of Ge28Sb12Se60 film(1.675 eV)is smaller than that of Ge20Sb15Se65 film(1.729 eV),and the corresponding wavelengths of the two are 740.3 nm and 717.2 nm.Finally,the microstructures of the two films are characterized by Raman spectra,and the reasons why the two chalcogenide films have different optical properties are explained from the bonding properties between the atoms.