Fabrication of High-aspect-ratio Nanohole Arrays on GaN Surface by Using Wet-chemical-assisted Femtosecond Laser Ablation

The drilling of high-aspect-ratio microholes has very important applications in automotive, aerospace, electronics and other areas. However, this is difficult to realize with conventional mechanical machining or electrical discharge machining approaches. Femtosecond laser ablation can potentially provide a good solution to this, but it also involves many technical difficulties. One of these is that the laser-induced plasma, as it expands out of the microhole, may transfer its energy to the side wall of the hole, which may affect the hole size and geometry. In this paper, the plasma – side wall interaction has been studied using a physics-based model, and the discovered characteristics of the interaction are discussed.

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Fabrication of high-aspect-ratio grooves with high surface quality by using femtosecond laser

Industrial Lubrication and Tribology ◽

10.1108/ilt-11-2020-0432 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Ru Zhang ◽

Chuanzhen Huang ◽

Jun Wang ◽

Hongtao Zhu ◽

Hanlian Liu

Keyword(s):

Laser Ablation ◽

Aspect Ratio ◽

Femtosecond Laser ◽

Process Parameters ◽

Laser Fluence ◽

High Aspect Ratio ◽

High Surface ◽

Content Type ◽

High Surface Quality ◽

Fs Laser

Purpose The purpose of this study is to fabricate high-aspect-ratio grooves with high surface quality by femtosecond laser (FS) to improve the machinability of silicon carbide (SiC) and optimize the process parameters in micromechanical applications. Design/methodology/approach Four contrast experiments are reported to characterize the FS laser grooving process for SiC with polarization direction, crystal orientation, multi-pass scanning and z layer feed, respectively. The effects of different experimental conditions on the groove characteristics, material removal rate (MRR), aspect ratio, heat affected zone (HAZ) and surface roughness Ra are analyzed. Findings The influence of increasing laser fluence and multi-scanning pass on the groove depth is greater than on the groove width. The MRR, aspect ratio, HAZ and Ra increased with the increase of laser fluence and multi-scanning pass. The direction of laser polarization affects the direction of hot electron injection but has little effect on the material characteristics. FS laser ablation is an isotropic process and there is no obvious change in different crystal orientations. The z-layer feed can significantly increase the groove width and depth and reduce HAZ and Ra. The maximum aspect ratio of 82.67% was fabricated. Originality/value The results contribute to the understanding of the removal mechanism and reduce the friction of the microfluidic device and improve the flowability in the FS laser ablation of SiC. This paper provides suggestions for the selection of suitable process parameters and provides a wider possibility for the application of micro-texture on SiC.

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The Interactions of Microhole Sidewall With Plasma induced by Femtosecond Laser Ablation in High-Aspect-Ratio Microholes

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4005431 ◽

2012 ◽

Vol 134 (1) ◽

Cited By ~ 2

Author(s):

Benxin Wu ◽

Sha Tao ◽

Shuting Lei

Keyword(s):

Laser Ablation ◽

Aspect Ratio ◽

High Aspect Ratio ◽

Material Removal ◽

Laser Energy ◽

Spatial Scales ◽

Femtosecond Laser Ablation ◽

Plasma Energy ◽

Direct Laser ◽

Fs Laser

High-aspect-ratio microholes have many important applications, but their drilling is very challenging. Femtosecond (fs) laser ablation provides a potential solution, but involves many complicated physical processes that have not been well understood, which have hindered its practical application. One of these is that the plasma induced by laser ablation at the hole bottom will transfer some of its energy to the hole sidewall as it expands in the microhole. The plasma–sidewall interaction has been rarely studied in literature, and it is still not clear if or not the energy transferred from the plasma is sufficient to cause significant material removal from the sidewall. Direct time-resolved observations are extremely difficult due to the small temporal/spatial scales and the spatial constraint inside the hole, while the sidewall characterization after laser ablation is difficult to distinguish between the possible material removal due to plasma energy transfer and that due to direct laser energy absorption by the sidewall. In this paper, a physics-based model is applied as the investigation tool to study the plasma–sidewall interaction in fs laser drilling of high-aspect-ratio microholes. It has been found that for the studied conditions the energy transferred from the plasma is not sufficient to cause significant material removal from the sidewall through any thermally induced phase change process.

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