Remarkable increase of thermoelectric power factor using plasma treatment in layered InGaO3(ZnO)m thin films

Abstract

Thermoelectric (TE) InGaZnO thin films grown on sapphire substrates by sputtering were optimized using a radio-frequency (RF) argon plasma treatment. The oxide thin films exhibited layered InGaO3(ZnO)2 superlattices with excellent crystallinity by using ZnO buffer layers and a post-annealing process at 900 °C. The plasma treatment under various RF powers induced excellent improvements in the electrical conductivity without structural changes. The carrier concentration was gradually increased as the RF power increased, and as a result, the TE power factor (PF) was significantly enhanced despite the reduced Seebeck coefficient. A maximum PF value was observed to be ∼0.2 × 10-5 at 500 K in the sample that was plasma treated at 150 W, where the carrier concentration was 4.9 × 10 19 cm-3. Copyright © 2012 John Wiley &Sons, Ltd.