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Pressure Dependence of the Low‐Frequency Dielectric Constant in III–VI Semiconductors
Author(s) -
Errandonea D.,
Segura A.,
Muñoz V.,
Chevy A.
Publication year - 1999
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/(sici)1521-3951(199901)211:1<201::aid-pssb201>3.0.co;2-v
Subject(s) - polarizability , dielectric , chemistry , semiconductor , condensed matter physics , capacitance , ion , lattice (music) , lattice constant , band gap , low frequency , materials science , optics , molecule , physics , electrode , optoelectronics , organic chemistry , astronomy , acoustics , diffraction
In this work we report on the pressure dependence of the low‐frequency dielectric constant parallel to the c ‐axis (ε ∥ ) in GaS, GaSe, and InSe as obtained from direct capacitance measurements. A large increase of ε ∥ with pressure has been observed. The pressure change of the lattice polarizability along the c ‐axis is calculated in the framework of a rigid‐ion model from the change of the angle of the anion–cation bond with respect to the layer plane, which results in a slight increase of the lattice contribution. Consequently, the pressure behaviour of ε ∥ is proposed to arise from the large increase of the electronic polarizability along the c ‐axis. This is explained through a decrease of the Penn gap, whose energy and pressure coefficients are shown to scale with those of the indirect gap in these compounds. A supplementary and reversible step‐increase of ε ∥ has been observed at 1.6 GPa in GaS. This increase has been associated to a phase transition that was reported by other authors.