Formation of nanodots and enhancement of thermoelectric power induced by ion irradiation in PbTe:Ag composite thin films

Present study demonstrates an enhancement in thermoelectric power of 10% Ag doped PbTe (PbTe:Ag) thin films when irradiated with 200 keV Ar ion. X-ray diffraction showed an increase in crystallinity for both PbTe and PbTe:10Ag nano-composite films after Ar ion irradiation due to annealing of defects in the grain boundaries. The preferential sputtering of Pb and Te ions in comparison to Ag ions resulted in the formation of nano-dots. This was further confirmed by X-ray photoelectron spectroscopy (XPS). Such an enhancement in thermoelectric power of irradiated PbTe:10Ag films in comparison to pristine PbTe:10Ag film is attributed to the decrease in charge carrier concentration that takes part in the transport process via restricting the tunneling of carriers through the wider potential barrier formed at the interface of nano-dots.