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Optical Constants of Tin Sulphide Single Crystals Measured by the Interference Method
Author(s) -
Elkorashy A. M.
Publication year - 1990
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.2221590238
Subject(s) - refractive index , birefringence , dielectric , attenuation coefficient , photon energy , materials science , polarization (electrochemistry) , optics , oscillator strength , scattering , molecular physics , chemistry , condensed matter physics , photon , physics , optoelectronics , astronomy , spectral line
The refractive index, n , of SnS single crystals is measured from reflectance after being normalized to account for the pronounced rise below the energy gap n is also measured by the interference method in the transparency region. An effective thickness smaller than the true one is introduced to account for the photon scattering by the layer structure of the material in this region. The effective thickness hypothesis gives a satisfactory explanation of the pronounced rise in reflectance for E < E g . The extinetion coefficient, k , is calculated from the measured absorption coefficient. Measurements are performed at room temperature using plane polarized light with the plane of polarization parallel to the a ‐ and b ‐crystallographic axes which lie in the plane of cleavage. The real and imaginary parts of the complex dielectric constant (ε r , ε i ) are calculated from the values of n and k . It is shown that SnS single crystals exhibit birefringence. Assuming that the SnS binding is partly ionic and partly covalent, the results of the optical constants are satisfactorly fitted to the model of a single effective oscillator.