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Optical Constants of Germanium Selenide Single Crystals in the Transparency Region
Author(s) -
Elkorashy A. M.
Publication year - 1988
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.2221490239
Subject(s) - refractive index , molar absorptivity , birefringence , dielectric , materials science , uniaxial crystal , attenuation coefficient , single crystal , optics , germanium , molecular physics , condensed matter physics , chemistry , crystallography , optical axis , silicon , physics , optoelectronics , lens (geology)
The refractive index, n , of GeSe single crystal is 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 satisfactory explanation of the pronounced rise in reflectance for E < E g . The extinction 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 c crystallographic axes which lie in the plane of cleavage. The real and imaginary parts of the complex dielectric constant (ϵ r , ϵ i ) as well as the reflectance and its phase change ( R , φ) are calculated from the values of n and k . It is shown that GeSe single crystal exhibits birefringence. Assuming that GeSe binding is partly ionic and partly covalent, the results of the optical constants are satisfactorily fitted to the model of a single effective oscillator.