Complete elastic characterization of lithium phosphorous oxynitride films using picosecond ultrasonics

• We report elastic characterization in LiPON thin film using pump and probe method.
• Frequency of the Brillouin oscillation is related to the longitudinal sound velocity.
• Surface acoustic mapping gives a direct access to Rayleigh wave properties.
• Coupling bulk and surface wave studies, Young modulus and Poisson ration is measured.

We report on a complete elastic characterization by picosecond ultrasonics technique of lithium phosphorous oxynitride (LiPON) thin films, which are nowadays, considered as promising solid-state electrolytes for microbatteries technology. Longitudinal sound velocity is deduced from Brillouin oscillation detection at variable incidence angles. The density is estimated through an interfacial energy analysis related to the echo amplitude decay. Transverse wave velocity is obtained across the dispersion curve of Rayleigh surface waves. Combining these different approaches, Young's modulus and Poisson's ratio of LiPON are finally found to be 79 GPa and 0.27, respectively.