Characterization of thin-film adhesion and phonon lifetimes in Al/Si membranes by picosecond ultrasonics. (17th May 2017)

• Record Type: Journal Article
• Authors: Grossmann, Martin; Schubert, Martin; He, Chuan; Brick, Delia; Scheer, Elke; Hettich, Mike; Gusev, Vitalyi; Dekorsy, Thomas
• Is Part Of: New journal of physics. Volume 19:Number 5(2017:May)
• Publication Date: 2017-05-17
• Subjects: interface adhesion -- time domain spectroscopy -- phonons -- non-destructive testing -- intrinsic damping; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/aa6d05
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: We quantitatively study interfacial adhesion in a two-layer membrane system consisting of Al and Si with femtosecond time-resolved laser spectroscopy. High-frequency acoustic pulses in the sub-THz regime are utilized to characterize the membrane system. In order to explain the distinct features of the measured data, a spring model for the Al/Si interface is employed. We show that acoustic dissipation in this system needs to be included for accurate modeling of the interface adhesion over a broad frequency range. This modeling approach yields a spring constant of η Al − Si = 17 kg nm − 2 s − 2, an acoustic phonon lifetime of τ Al = 68 ps at 240 GHz in polycrystalline Al and a frequency dependence of the lifetime in Si ∝ ω − 1 in the frequency range from 50–800 GHz.