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

✍ Scribed by T. Plecháček; J. Navrátil; J. Horák

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 199 KB
• Volume: 165
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9486

✦ Synopsis

From IR reflectivity spectra measurement on natural (0001) cleavage planes of Bi 2Àx Sb x Se 3 single crystals (space group D 5 3d -R3 3m), values of plasma resonance frequency x p 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 Bi 2Àx Sb x Se 3 single crystals (for x = 0.0 -0.4) was obtained. There is a maximum in this dependence at lower Sb concentration (x D 0.024). This effect is explained by a model of point defects, where both the concentration of negatively charged native defects in a Bi 2 Se 3 lattice (anti-site defect Bi 0 Se , ''seven-layer lamellae'' Bi 3 Se 4 À ) 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 R H r in the range from 500 to 1200 cm 2 /Vs is explained.