Ultrafast laser interaction with transparent multi-layer SiO2/Si3N4 films

TL;DR

This study explores how ultrafast laser pulses induce localized crystallization and elemental redistribution in multi-layer SiO2/Si3N4 films, revealing new pathways for material modification at the nanoscale.

Contribution

It demonstrates laser-induced elemental intermixing and silicon nanocrystal formation in amorphous dielectric multilayers, a novel approach for nanoscale material engineering.

Findings

Laser exposure causes elemental intermixing in multilayers.

Silicon nanocrystals form and localize within the layers.

Energy is channeled transversely beyond the laser spot.

Abstract

We investigate the use of ultrafast lasers exposure to induce localized crystallization and elemental redistribution in amorphous dielectric multi-layers, composed of alternating Si3N4and SiO2layers of sub-micron thickness. Specifically,we report on the occurrence of a laser-induced elemental intermixing process and on the presence of silicon nanocrystals clusters localized within the multi-layers structure. The spatial distribution of these clusters goes significantly beyond the zone under direct laser exposure providing evidences of energy being channeled transversely to the laser propagation axis at the interface of the nanoscale layers. Thanks to the extreme conditions reigning during laser exposure, this process transposed to various materials may offer a pathway for local and selective crystallization of a variety of compounds and phases, difficult to obtain otherwise.