Superiority of ion irradiation over annealing for enhancing the thermopower of PbTe thin films

Present study reveals that swift heavy ion (SHI) irradiation enhances thermoelectric properties and the annealing deteriorates thermoelectric performance of PbTe thin film. X-ray diffraction (XRD), Atomic force microscopy (AFM) and Rutherford backscattering spectrometry (RBS) measurements are performed for phase formation, surface morphology and elemental composition of all the samples, respectively. Electrical conductivity (sigma) and thermo power (S) measurement of all the samples have also been measured using four probe method. The increase in thermo power (S) is about 40% upto high temperature (about 520 K) after irradiation whereas it decreases on annealing treatment. These findings are discussed on the basis of density of states enhancement or carrier scattering due to the point d efects after SHI irradiation.