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Optical Properties of Titanium‐Doped Sb 2 Te 3 Single Crystals
Author(s) -
Drašar Č.,
Lošťák P.,
Navrátil J.,
Černohorský T.,
Mach V.
Publication year - 1995
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.2221910226
Subject(s) - materials science , dielectric , transmittance , spectral line , analytical chemistry (journal) , photon energy , absorption edge , doping , scattering , crystal (programming language) , attenuation coefficient , absorption (acoustics) , relaxation (psychology) , impurity , band gap , optics , photon , chemistry , optoelectronics , physics , psychology , social psychology , chromatography , astronomy , computer science , composite material , programming language , organic chemistry
Abstract The reflectance and the transmittance spectra in the IR region are measured on Ti‐doped Sb 2 Te 3 single crystal samples grown by a modified Bridgman technique. The plasma resonance frequency, the optical relaxation time, and the high‐frequency dielectric constant are determined by fitting the Drude‐Zener formulas to the reflectance spectra. It is found that Ti impurities in Sb 2 Te 3 behave as donors. The transmittance spectra are used for the determination of the dependence of the absorption coefficient K on the energy of incident photons. The optical width of the energy gap is found to decrease with increasing Ti content. The values of the exponent α from the relation of K ∼ λ α for the long‐wavelength absorption edge range within the interval of 1.8 to 2.2, i.e. the dominant scattering mechanism of free current carriers in Sb 2 Te 3 crystals doped with Ti atoms is the scattering by acoustic phonons.