Thermoelectric transport properties of Bi-Te based thin films on strained polyimide substrates

Effect of stress on lattice defect concentration and thermoelectric properties of Bi-Te based thin films is investigated. Both Bi-Sb-Te and Bi-Se-Te films were individually sputtered on a stretched polyimide (PI) substrate and annealed at elevated temperature. With the PI strain varying from 0% to 10%, the carrier concentration increases triple times for the Bi-Sb-Te films and decreases by 35% for the Bi-Se-Te films. The Seebeck coefficient and electrical resistivity are also found to vary monotonically with PI strain. A stress-mediated Te vacancy formation mechanism is proposed to explain the changes of thermoelectric properties of Bi-Te films on strained PI substrates. (C) 2014 AIP Publishing LLC.