Regensburg 2022 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 35: Nanomaterials: Structure & Properties
MM 35.7: Vortrag
Donnerstag, 8. September 2022, 17:30–17:45, H46
Laser-Ultrasonics Reveals the Complex Mechanics of Nanoporous Silicon — •Marc Thelen1, Nicolas Bochud2, Manuel Brinker1, Claire Prada3, and Patrick Huber1,4,5 — 1MXP, TUHH, Hamburg, Germany — 2MSME, CNRS UMR 8208, UPEC, Univ Gustave Eiffel, Creteil, France — 3Institut Langevin, ESPCI Paris, Université PSL, CNRS, Paris, France — 4CXNS, DESY, Hamburg, Germany — 5CHyN, UHH, Hamburg, Germany
Nanoporosity in silicon leads to completely new functionalities of this mainstream semiconductor with numerous discoveries in fields ranging from nanofluidics and biosensorics to drug delivery, energy storage and photonics. Nevertheless, the mechanical properties, critical for a variety of applications, remain difficult to characterise comprehensively. The study presented here aims to address this problem by utilising laser-excited elastic guided waves, detected in dry and liquid-infused porous silicon. Among other things, the experiments reveal that the self-organised formation of 100 billions of parallel nanopores per square centimetre cross section results in an effective stiffness reduction of about 80 %, a nearly isotropic elasticity perpendicular to the pore axes and a higher stiffness along the pore axis, altogether leading to significant deviations from bulk silicon. This thorough assessment of the wafer-scale mechanics of nanoporous silicon and recent breakthroughs in laser ultrasonics therefore open up entirely new frontiers for in-situ, non-contact and non-destructive mechanical characterisation of complex porous material systems [1].
[1] Thelen, M., Bochud, N. et al., Nat Commun., 12, 3597 (2021)