Influence of La impurities to the dielectric properties and thermal memory effect of incommensurate phase of TiInS2 ferroelectric semiconductor

Full text : For the first time it has been studied the influence of La impurity to low-frequency dielectric properties of TiInS2 layered crystal under influence of optical radiation with various intensity in the wide temperature interval. It has been established that only in the range of existence of incommensurate phase of TiInS2 crystal with La impurity the illumination of crystal during measurement essentially modifies the the form of temperature dependence of dielectric constant. In this work it has been firstly investigated under the previous cooling of crystal in the presence of various value of electric field intensity and also after a long isothermal annealing at different temperature in the range of existence of incommensurate phase of TiInS2 crystal with La impurity. It has been accounted the results of influence of optical radiation to the peak of pyroelectric current registered in the vicinity. It has revealed that experiment observed effects caused by processes of thermo-localization of charge carriers on defective levels in band-gap level of crystal with forming of local polarized states