LAUSR

Measurements were performed using the picosecond ultrasonic technique to evaluate thermal and elastic properties of a nanoscale copper (Cu) thin-film in the present study. A 50-nm thick Cu film was deposited using an e-beam evaporator, and the reflectance changes induced by thermal diffusion and acoustic wave propagation in the film upon illumination of femtosecond laser pulses were recorded. A numerical analysis was conducted using the finite difference method in order to extract the thermal conductivity and Young’s modulus of the material. Results showed that the film’s thermal conductivity decreased compared to the bulk property while its elastic modulus increased due to the scale effect originating from changes in microstructural contributions to the resultant characteristics. Results were compared to literature values and validated. The present study demonstrates an advanced measurement technique that can effectively and simultaneously analyze thermomechanical characteristics of nanoscale materials in a nondestructive way.