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Optical and Electrical Investigations of n‐Type Bi 2 Se 3 Single Crystals
Author(s) -
Stordeur M.,
Ketavong K. K.,
Priemuth A.,
Sobotta H.,
Riede V.
Publication year - 1992
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221690222
Subject(s) - condensed matter physics , anisotropy , seebeck coefficient , electrical resistivity and conductivity , hall effect , relaxation (psychology) , materials science , dielectric , isotropy , optics , physics , quantum mechanics , psychology , social psychology , optoelectronics
Bi 2 Se 3 single crystals were prepared in the electron concentration range from 1.8 × 10 19 to 5.6 × 10 19 cm –3 . At room temperature experimental values are given for the specific electrical resistivity, for the Hall and Seebeck coefficients, and the ir‐plasma reflectivity spectra were measured in the wave number range from 300 to 4000 cm –1 . For the first time it was found that not only the resistivity and the plasma reflectivity but also the thermopower show a distinct anisotropy perpendicular and parallel to the trigonal c ‐axis, whereas the Hall effect is isotropic. In terms of a one‐carrier, one‐valley conduction band model with elliptical isoenergy surfaces and a nonparabolic dispersion the anisotropy of the thermopower can be explained in the extrinsic range by an anisotropic mixed scattering mechanism on acoustic phonons and ionized impurities in the relaxation time approximation. In this frame a quantitative, consistent interpretation is reached for all experimental data. The calculated values for the high‐frequency dielectric constant, the carrier density, the Fermi level, the parameter of nonparabolicity, the mean optical relaxation times, the effective masses and the drift mobilities are given.