Scalable Thermal Engineering via Femtosecond Laser-Direct-Written Phononic Nanostructures

Abstract

Modern electronics demands innovative thermal management strategy beyond conventional approaches. Here, a transformative platform bridging laboratory-scale phononic nanostructures and industrial-scale thermal engineering is demonstrated via femtosecond laser-induced periodic surface structures (fs-LIPSS). Laser-direct-written phononic metamaterials are achieved with throughputs exceeding 10−⁵ m2 s−1—three orders of magnitude faster than electron beam lithography—while maintaining nanoscale resolution. Applied to silicon membranes, the fs-LIPSS reduce thermal conductivity from 101 to 76 W m−1 K−1, surpassing thin-film limit predicted by Fuchs–Sondheimer model. Monte Carlo simulations corroborate these findings, showing that long mean free paths are limited by the fs-LIPSS, while ablation-induced roughness mediates isotropic modulation of thermal conductivity via enhanced diffuse scattering. Thus, this maskless and resist-free process enables the fabrication of phononic nanostructures that are CMOS-compatible and scalable to wafer-level dimensions. This work establishes the fs-LIPSS as a versatile approach that makes phonon engineering practical for real-world devices, unlocking applications in quantum technologies, on-chip energy conversion, and high-performance computing.

Applied Functional Materials XX, e25269 (2025)