Charge trapping/detrapping induced lattice polarization/relaxation processes

The consequence of the coupling of a charged particle with a polarization field is the formation of a quasi particle called polaron. The degree of localization of the charge depends on the nature of this coupling. In this way, trapping at an atomic scale is described as resulting from the evolution of a coupling involving successively the electronic polarization field, the infra-red polarization field and the quasi static ionic polarisation field. The internal energy stored in the surrounding medium polarized by the charge is as high as the charge is well localized. The maximum of this energy is obtained for the quasi static polarization field. Its magnitude is of the order of 5 to 10 eV per trapped charge. The trapping of charges modifies the thermal properties of the material. The variation of the specific heat observed is interpreted as the consequence of an evolution of the coupling of the charge with the ionic polarization field in contact with the phonon bath.