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

[Display omitted] •Cu-doped Bi2Te3 thin films were deposited by magnetron sputtering.•The substrates were used with the Si wafer, glass, and polyimide.•The characteristics of films were different with each other.•The influence of thermal stress in Cu-doped Bi2Te3 thin films was investigated. 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.