Optical Properties of Cd0.9Zn0.1 Te Studied by Variable Angle Spectroscopic Ellipsometry Between 0.75 and 6.24 eV

摘要

Optical properties of Cd(sub 0.1) Te (CZT) were studied by variable angle spectroscopic ellipsometry (VASE). Measurements made by VASE were performed on CZT and CdTe samples in air at room temperature at multiple angles of incidence. A parametric function model was employed in the VASE analysis to determine the dielectric functions (var-epsilon)=(var-epsilon) (sub 1)+I(var epsilon) (sub 2) in the range of 0.75 to 6.24 eV. A two-oscillator analytical model was used to describe the dielectric response of native oxides on CZT. Surface oxide optical properties and thickness on CZT were also determined in conjunction with the VASE measurement and analysis of a CdTe sample. Two samples of CZT of different oxide thicknesses were measured and their optical constants were coupled together in a multiple-sample, multiple-model VASE analysis to resolve correlations between fitting parameters. Effective medium approximation (EMA) was used to describe the optical properties of the CZT oxide with roughness. A Kramers-Kronig self-consistency check of the real and imaginary parts of the Cd (sub 0.9) Zn (sub 0.1) dielectric functions was performed over the energy range 0.75 to 6.24 eV. Intensity transmission measurements were made on the Cd (sub 0.9) Zn (sub 0.1) Te and CdTe, showing the absorption energy band edges of (approximately) 1.58 and 1.46 eV. Intensity transmission measurements were made on the Cd (sub 0.9) Zn (sub 0.1) Te and CdTe, showing the absorption energy band edges of (approximately) 1.58 and 1.46 eV, respectively.