Modifying the Thermoelectric Transport of Sb₂Te₃ Thin Films via the Carrier Filtering Effect by Incorporating Size-Selected Gold Nanoparticles

Hot energy carrier filtering as a means to improve the thermoelectric (TE) property in Sb2Te3 thin film samples having size-selected Au nanoparticles (NPs) is investigated in the present study. Nonagglomerated Au NPs with a very narrow size distribution grown by an integrated gas-phase synthesis setup are incorporated into the Sb2Te3 thin film synthesized by RF magnetron sputtering. TE properties have been investigated as a function of size-selected Au NP concentrations and compared with that of a nanocomposite sample having non-size-selected Au NPs. An increase in the Seebeck coefficient and power factor, along with a slight decrease in electrical conductivity, is observed for samples with a NP size of minimum variance. Further, the Kelvin probe force microscopy and conducting atomic force microscopy techniques were employed to understand the nature of the interface and charge transport across the Sb2Te3 matrix and Au NPs. The study provides an opportunity to modulate the TE properties in Sb2Te3 thin films by constructing a metal–semiconductor heterostructure through controlling the concentration and randomness to achieve a high TE performance.