Light-induced ionic polarization in CdZnTe:V semiconductor crystals as a source of giant enhancement of nonlinear effects

We report on experimental observation of a remarkable light-induced increase in the low-frequency dielectric constant in doped CdZnTe:V (CZT:V) semiconductor crystals and show that this increase is due to electric dipoles forming under illumination. Our findings provide strong evidence that CZT:V undergoes a photoinduced phase transition at room temperature from a nonpolar to polar phase. A related symmetry-breaking effect is responsible for giant light-induced enhancement of the nonlinear effects (the electro-optic effect and electrostriction) previously observed in these crystals.