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Photoconductivity in germanium selenide single crystals
Author(s) -
Elkorashy A. M.
Publication year - 1989
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.2221520128
Subject(s) - photoconductivity , materials science , germanium , band gap , atmospheric temperature range , photon energy , analytical chemistry (journal) , condensed matter physics , optics , molecular physics , optoelectronics , chemistry , silicon , photon , physics , chromatography , meteorology
Abstract The photoconductivity spectral response is measured for GeSe single crystals at different temperatures from room temperature to near liquid nitrogen temperature. Measurements are carried out with plane polarized light with the plane of polarization parallel to the a ‐ and c ‐crystallographic axes which lie in the plane of cleavage. The photon energy range of measurements extends from 0.5 to 3.0 eV. The photoconductivity energy gap is determined from the spectral response by the Moss rule. The room temperature photoconductivity energy gap is found to be (1.144 ± 0.011) and (1.167 ± 0.025) eV for the a ‐ and c ‐axes, respectively. The temperature dependence of the photoconductivity energy gap is also deduced. It is found that it is linear between 93 and 250 K with a negative temperature coefficient equal to −(0.35 ± 0.01) meV/K for the a ‐axis. The results for the c ‐axis show a large discrepancy which is attributed to crystal lattice bending introduced during the cleavage process. The minority carrier lifetime is determined from the photoconductivity frequency response using square modulated illumination. The photoconductivity frequency response is found to be characterized by two different lifetimes.