Laser ablative fabrication of nanocrowns and nanojets on the Cu supported film surface using femtosecond laser pulses

TL;DR

This study investigates how femtosecond laser pulses create nanostructures like nanocrowns and nanojets on copper films, revealing formation mechanisms and potential applications in enhancing photoluminescence signals.

Contribution

It demonstrates the formation dynamics of nanocrowns and nanojets on copper films of varying thicknesses using femtosecond laser pulses, highlighting the role of subsurface boiling.

Findings

Single femtosecond pulse creates a nanojet on 120-nm Cu film.

Nanospike number depends linearly on pulse energy.

Subsurface boiling influences nanostructure formation.

Abstract

Formation dynamics of the nanojets and nanocrowns induced on the surface of the Cu supported films of different thickness under the impact of tightly focused femtosecond pulses was studied in detail. We show that the single-shot fs-pulse irradiation of the 120-nm-thick Cu film results in formation of a single nanojet, which splits at increased pulse energy into two and then into a plurality of periodically arranged nanospikes eventually acquiring the form of the so-called nanocrown. The number of nanospike in the nanocrown was found to be linearly dependent on the pulse energy and nanocrown radius. The key role of subsurface boiling occurring on the metal film-substrate interface in the formation process of crown-like nanostructures was revealed by comparing the obtained results with the formation dynamics studied for thinner 60-nm and 20-nm-thick Cu films. In addition, the applicability of the fabricated nanostructures as low-cost substrate for photoluminescence signal enhancement of the organic dyes is also discussed in this paper.