Augmented near-room-temperature power factor of homogenously grown thermoelectric ZnO films

Abstract

Future applications in power generation for wearable and portable electronics or active cooling for chips will benefit from near-room-temperature thermoelectric performance enhancement. Ga-doped ZnO (GZO) thin films are potential thermoelectric materials as they have the advantages of high cost-effectiveness, low toxicity, excellent stability, and high optical transparency. Inserting a ZnO buffer layer between the sapphire substrate and GZO thin films could contribute to optimizing carrier mobility and further improving electrical transport properties. However, thermoelectric performance at near-room-temperature ranges still needs to be promoted for practical applications. In this present study, ZnO single-crystal slices were directly selected as substrates for homogenously growing GZO thin films to further modify the substrate–film interface. The high Hall mobility of 47 cm2 V−1 s−1 and weighted mobility of 75 cm2 V−1 s−1 could be realized, resulting in better electrical transport performance. Consequently, the homogenously grown GZO thin films possessed competitively prominent power factor values of 333 μW m−1 K−2 at 300 K and 391 μW m−1 K−2 at 373 K. This work offers an effective avenue for optimizing the thermoelectric properties of oxide-based thin films via homogenous growth.