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arXiv · 2010.14947

Laser-Excited Elastic Guided Waves Reveal the Complex Mechanics of Nanoporous Silicon

Marc Thelen·Nicolas Bochud·Manuel Brinker·Claire Prada·Patrick Huber
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Abstract

Nanoporosity in silicon leads to completely new functionalities of this mainstream semiconductor. A difficult to assess mechanics has however significantly limited its application in fields ranging from nanofluidics and biosensorics to drug delivery, energy storage and photonics. Here, we present a study on laser-excited elastic guided waves detected contactless and non-destructively in dry and liquid-infused single-crystalline porous silicon. These experiments reveal that the self-organised formation of 100 billions of parallel nanopores per square centimetre cross section results in a nearly isotropic elasticity perpendicular to the pore axes and an 80% effective stiffness reduction, altogether leading to significant deviations from the cubic anisotropy observed in bulk silicon. Our thorough assessment of the wafer-scale mechanics of nanoporous silicon provides the base for predictive applications in robust on-chip devices and evidences that recent breakthroughs in laser ultrasonics open up entirely new frontiers for in-situ, non-destructive mechanical characterisation of dry and liquid-functionalised porous materials.

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Marc Thelen, Nicolas Bochud, Manuel Brinker, Claire Prada, Patrick Huber. 2020-10-28. Laser-Excited Elastic Guided Waves Reveal the Complex Mechanics of Nanoporous Silicon. https://doi.org/10.1038/s41467-021-23398-0

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