Arnaud Devos

A different way of performing picosecond ultrasonic measurements in thin transparent films based on laser-wavelength effects

We present a way of using picosecond ultrasonics to simultaneously get the thickness and elastic properties of thin dielectric layers. This is based on the use of a blue probe which is shown to improve the detection of acousto-optic oscillations in the dielectric from which the sound velocity can be measured from the refractive index. At the same wavelength a strong response of the silicon is used to detect the arrival of the acoustic pulse. We apply this scheme to various materials deposited on silicon substrates.

Acoustic attenuation measurements in transparent materials in the hypersonic range by picosecond ultrasonics

The authors report on acoustic attenuation measurements in transparent thin films by picosecond ultrasonics. This ultrafast technique has already been proposed for such measurements but usually attenuation is overestimated and a specific sample configuration is needed. Here they present another way of using this technique which overcomes both difficulties. Experimental results obtained for silica show a very good agreement with literature. This validates the protocol which is then applied to various other materials used in microelectronics.

Comment on “Visualizing coherent phonon propagation in the 100 GHz range: A broadband picosecond acoustic approach” [Appl. Phys. Lett.98, 011901 (2011)]

range: A broadband picosecond acoustic approach” †Appl. Phys. Lett. 98, 011901 „2011...‡ E. Courtens, B. Rufflé, M. Foret, R. Vacher, and A. Devos Laboratoire Charles Coulomb, UMR 5221, Université Montpellier 2, F-34095 Montpellier, France Laboratoire Charles Coulomb, UMR 5221, CNRS, F-34095 Montpellier, France UMR CNRS 8250, Institut d’Electronique, de Microélectronique et de Nanotechnologie, BP 69, Avenue Poincaré, F-59652 Villeneuve d’Ascq Cedex, France