Photodielectric effect in TlInS2 activated by the La impurity

The influence of light on the low-frequency dielectric properties of the TlInS 2 layered crystal is investigated for the first time. It is established that the illumination of the crystal during measurements leads to a substantial change in the behavior of the temperature dependence of the permittivity ɛ of the TlInS 2 compound doped with the lanthanum impurity in the range of the existence of the incommensurate phase. The temperature dependences of the permittivity ε of the TlInS 2 compound doped with the lanthanum impurity after preliminary cooling of the crystal in constant electric fields with different strengths are studied for the first time. The inference is made that the experimentally observed photodielectric effect is associated with the localization of charge carriers at defect levels in the band gap of the crystal with the formation of local polarized states.