Effect of Sb additive on structural and optical properties of Se–Te–Sb thin films

• Published in: Applied physics. A, Materials science & processing Vol. 118; no. 3; pp. 981 - 988
• Main Authors: Abdel-Rahim, M. A., Hafiz, M. M., Mahmoud, A. Z.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2015
• Subjects: Antimony; Characterization and Evaluation of Materials; Condensed Matter Physics; Constants; Dispersions; Machines; Manufacturing; Materials science; Nanotechnology; Optical and Electronic Materials; Physics; Physics and Astronomy; Processes; Refractive index; Refractivity; Surfaces and Interfaces; Thin Films; X-ray diffraction; Chalcogenide Glass; Effective Coordination Number; Cohesive Energy; Quartz Glass Ampoule; Lattice Dielectric Constant
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-014-8853-x

Amorphous Se 85− x Te 15 Sb x ( x  = 2.5, 5 and 7.5 at.%) thin films were deposited on glass substrates by thermal evaporation. The absorption coefficient was determined from the transmittance, and reflectance spectra in the wavelength range 400–2500 nm. Various optical constants have been calculated for the studied compositions. The mechanism of the optical absorption follows the rule of non-direct transition. It was found that the optical energy gap, E g , decreases from 1.42 to 1.36 eV with increasing Sb content from 2.5 to 7.5 at.%. These results can be interpreted on the basis of the chemical bond approach proposed by Bicermo and Ovshinsky. On the other hand, the optical constants such as refractive index, n , and extinction coefficient, K ex , of the films were studied. The dispersion of the refractive index was discussed in terms of single-oscillator Wemple–DiDomenico model. The influence of Sb content on the structure for the annealed films was investigated using X-ray diffraction (XRD) and scanning electron microscopy. The average particle size of the crystalline size for Te 0.04 Se 0.96 phase deduced from XRD pattern. This average decreases with increasing Sb content.