Free Current Carrier Concentration and Point Defects in Bi2−xSbxSe3 Crystals

• Published in: Journal of solid state chemistry 2002-04, Vol.165 (1), p.35-41
• Main Authors: PLECHACEK, T, NAVRATIL, J, HORAK, J
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; crystals of tetradymite structure; electrical conductivity; Exact sciences and technology; Hall coefficient; Infrared and raman spectra and scattering; lattice defects; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other nonmetallic inorganics; Physics; reflectivity in the plasma resonance frequency region
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.2001.9486

From IR reflectivity spectra measurement on natural (0001) cleavage planes of Bi2−xSbxSe3 single crystals (space group D53d–R3m), values of plasma resonance frequency ωp were determined. Using the model respecting the existence of light and heavy electrons the dependence of free current carriers concentration on Sb-atom content in Bi2−xSbxSe3 single crystals (for x=0.0 – 0.4) was obtained. There is a maximum in this dependence at lower Sb concentration (x ≅ 0.024). This effect is explained by a model of point defects, where both the concentration of negatively charged native defects in a Bi2Se3 lattice (anti-site defect Bi′Se, “seven-layer lamellae” Bi3Se−4) and the concentration of vacancies in a selenium sublattice (V••Se) decreases with Sb content. On this basis the observed rise of the Hall mobility RHσ in the range from 500 to 1200 cm2/Vs is explained.