Optical constants of Bi2Te3 and Sb2Te3 measured using spectroscopic ellipsometry

In this work, we present the optical constants of bismuth telluride (Bi₂Te₃), and antimony telluride (Sb₂Te₃) determined using spectroscopic ellipsometry (SE). The spectral range of the optical constants is from 404 nm to 740 nm. Bi₂Te₃ and Sb₂Te₃ films with different thicknesses were grown by metalorganic chemical vapor deposition (MOCVD). Multiple sample analysis (MSA) technique was employed in order to eliminate the parameter correlation in the SE data analysis caused by the presence of the overalyer on top of Bi₂Te₃ and Sb₂Te₃ films. Optical constants and thicknesses for both Bi₂Te₃ and Sb₂Te₃ overlayers were also determined. Independent Bi₂Te₃ and Sb₂Te₃ samples were used to check the results obtained. In addition, SE analysis was performed on two Sb₂Te₃ samples after being etched in diluted NH₄OH solution in order to characterize the overlayer and confirm the reliability of the results.