Atomic understanding of structural deformations upon ablation of graphene

• Published in: Nano select Vol. 2; no. 11; pp. 2215 - 2224
• Main Authors: Alaghemandi, Mohammad, Salehi, Leili, Samolis, Panagis, Trachtenberg, Benyamin T., Turnali, Ahmet, Sander, Michelle Y., Sharifzadeh, Sahar
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01-11-2021; Wiley; Wiley-VCH
• Subjects: Ablation; Aerospace materials; Carbon; Deformation; Design parameters; Energy; Femtosecond pulses; Graphene; graphene deformation; Heat; Illumination; image processing; Laser ablation; Lasers; Machine learning; Molecular dynamics; NANOSCIENCE AND NANOTECHNOLOGY; reactive molecular dynamics; Silicon wafers; Simulation; Temperature; Ultrafast lasers
• ISSN: 2688-4011; 2688-4011
• DOI: 10.1002/nano.202000248

We investigate the atomic rearrangement in graphene under femtosecond pulse illumination with reactive molecular dynamics simulations and compare with ultra‐fast laser ablation experiments. To model the impact of the laser pulse irradiation, heat is locally applied to a selected area of the graphene layer and the resulting structural deformation is simulated as a function of time, providing a detailed understanding of the bond breaking process under laser illumination and subsequent re‐equilibration after the pulse is turned off. Analysis of the atomic dynamics indicates that the types of defects formed depend on the pulse energy and exposure duration. By varying the exposed area, we determine that the shape of the ablated area is not only a function of the pulse energy, but also of the beam spot size and pulse repetition. Furthermore, we apply a machine learning approach to extrapolate our simulated data to experimental length scales and reproduce the trends in ablated area as a function of temperature. Our study provides a first step towards understanding the design parameters for graphene nano‐patterning.
Gaining fundamental insights into light‐matter interaction on the atomic scale is extremely valuable for any micromachining process. With a reactive molecular dynamics model, validated by comparison to experiment, theory‐driven optimization of the ablation parameters will help advance precision graphene patterning, and developing design principles for fabricating 3D structures out of 2D layers.