Stress-induced change of Cu-doped Bi2Te3 thin films for flexible thermoelectric applications

Abstract Cu-doped Bi2Te3 thin films were deposited on Si wafer, glass, and polyimide substrates at 200 °C using magnetron sputtering. During the deposition process, it is confirmed that thermal stress occurred at the films due to the mismatch of the coefficient of thermal expansion between the films and the substrates. As substrates with different coefficients of thermal expansion were used, the changes of crystal growth, morphologies, and thermoelectric properties of the Cu-doped Bi2Te3 thin films were investigated.