Composition Dependent Optical Properties of Vacuum Deposited Sb2xBi2(1-x)Te3 Thin Films For Thermoelectric Applications

Author(s): G.D. Deshmukh

Abstract:

The ternary thin films Sb2xBi2(1-x)Te3, a class of group V-VI materials were deposited via sublimation by thermal evaporation in vacuum. These materials are known for their thermoelectric and topological insulating properties. The systematic exploration of Sb2Te3- Bi2Te3 alloys, achieved by tuning antimony concentrations, reveals significant manipulation of their electronic band structure and their optical response. The films are polycrystalline exhibiting rhombohedral or hexagonal structure. The grain size observed about 20-60 nm. Optical transmittance spectra show optical transparency in the spectral region between 1100 nm to 2500 nm, between 0% to 32% corresponding to the composition. The optical reflectance varies from 12% to 70 % and increases with increase in the composition. The optical band gap has been found to be direct and allowed, it vary between 0.92 eV to 1.06 eV with composition. Refractive index diverges from 1.58 to 8.42 and extinction coefficient varies from 0.42 to 3.02 for all the compositions.

keywords:

Pages: 95-100     |    2 View     |    0 Download