Molecular-beam-epitaxy grown thin films and bulk crystals of Cd1-xZnxTe have been studied by using various experimental methods. The samples exhibit bistable conductivity, peculiar optical properties and hysteresis in the dielectric constant. The experimental results indicate that the presence of isolated Zn atoms plays a crucial role in the ferroelectric behavior of Cd1-xZnxTe. Based on the experimental results, we propose a microscopic model that takes into consideration formation of point defects in the crystal lattice, namely Zn interstitials, Zn and cation vacancies, VCd. The presence of these defects and the formation of vacancy-interstitial pairs that constitute local electric dipoles provide a plausible explanation for the bistable conductivity, the changes in the luminescence spectra and of the hysteretic behavior of the electrical polarization.
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