Ablation in Externally Applied Electric and Magnetic Fields

Abstract

To harness light-matter interactions at the nano-/micro-scale, better tools for control must be developed. Here, it is shown that by applying an external electric and/or magnetic field, ablation of Si and glass under ultra-short (sub-1 ps) laser pulse irradiation can be controlled via the Lorentz force F = e E + e [ v × B ] , where v is velocity of charge e, E is the applied electrical bias and B is the magnetic flux density. The external electric E-field was applied during laser ablation using suspended micro-electrodes above a glass substrate with an air gap for the incident laser beam. The counter-facing Al-electrodes on Si surface were used to study debris formation patterns on Si. Debris was deposited preferentially towards the negative electrode in the case of glass and Si ablation. Also, an external magnetic field was applied during laser ablation of Si in different geometries and is shown to affect ripple formation. Chemical analysis of ablated areas with and without a magnetic field showed strong chemical differences, revealed by synchrotron near-edge X-ray absorption fine structure (NEXAFS) measurements. Harnessing the vectorial nature of the Lorentz force widens application potential of surface modifications and debris formation in external E-/B-fields, with potential applications in mass and charge spectroscopes.

Magnetic-field assisted laser ablation of silicon

“…This paper aims to investigate the influence of the external magnetic field on the ablation process following ultrashort pulses. The positive effect of the external magnetic field has already been demonstrated using nanosecond [10,11], picosecond [15], and femtosecond laser pulses [12][13][14]. In our case, femtosecond laser pulses in the infrared range have been applied to investigate the effects and driving mechanisms in the micromachining of silicon surfaces with the externally applied magnetic field.…”

“…Changing the ambient atmosphere, including conditions, namely, the application of various processing gases [3] or liquid flows top layers [4][5][6], gives additional flexibility to the ablation process. Various studies have been carried out by some research groups to investigate the effect of the magnetic field on the ablation process as well [7][8][9][10][11][12][13][14][15]. However, the applied field in these studies was mainly perpendicular to the laser beam close to the surface.…”

Liquid vortexes and flows induced by femtosecond laser ablation in liquid governing formation of circular and crisscross LIPSS

“…Additionally, UPLA/P is capable of surface structuring of a large variety of materials including metals, ceramics, semiconductors, dielectrics, polymers, and two-dimensional materials 17−27 , which involve hard-to-treat materials 26 . Recent UPLA/P innovations have unveiled that new factors such as electric and magnetic fields 28,29 , high-pressure shockwave 30 , and persistent bubbles 18,31 generated during UPLA/P or exerted externally may become new keys to manipulate structure morphologies. Despite the success in generating new types of structures at different scales, it is still challenging to further enrich the structural diversity and unveil the underlying key factors that cause the differences.…”

Influence of an external electric field on the energy dissipation at the initial stage of laser ablation

“…Several methods were proposed to optimize the ablation process, for instance, liquid confinement layers [6][7][8] or laser treatment of materials in the presence of different gases [9]. An alternative and promising way to control laser micromachining is via application of external magnetic or electric fields [10][11][12][13][14][15][16][17][18][19]. An influence of the external magnetic field on the ablation process is still under intense investigations and debates, however, less attention was given so far to the role of an externally applied electric field to the energy deposition and dissipation.…”

“…An influence of the external magnetic field on the ablation process is still under intense investigations and debates, however, less attention was given so far to the role of an externally applied electric field to the energy deposition and dissipation. Moreover, the external E-field in the recent investigation [17] was perpendicular to the laser beam. In contrast, in our experiments, we apply an external electric field along the direction of the laser pulse.…”