Femtosecond Laser-Induced Periodic Surface Structures in Titanium-Doped Diamond-like Nanocomposite Films - Effects of the Beam Polarization Rotation

At a Glance

Metadata	Details
Publication Date	2023-01-13
Journal	Materials
Authors	S.M. Pimenov, E.V. Zavedeev, B. Jaeggi, Beat Neuenschwander
Institutions	Bern University of Applied Sciences, Prokhorov General Physics Institute
Citations	7
Analysis	Full AI Review Included

Technical Documentation & Analysis: Femtosecond Laser-Induced Periodic Surface Structures in Ti-DLN Films

Reference: Pimenov et al., Femtosecond Laser-Induced Periodic Surface Structures in Titanium-Doped Diamond-like Nanocomposite Films: Effects of the Beam Polarization Rotation, Materials 2023, 16, 795.

Executive Summary

This research demonstrates precise control over nanoscale surface morphology and friction properties in carbon-based films using femtosecond laser processing, validating advanced surface functionalization techniques highly relevant to 6CCVD materials.

Material Focus: Study utilizes Titanium-Doped Diamond-Like Nanocomposite (Ti-DLN) films (17-18 at.% Ti) as a platform for laser-induced periodic surface structures (LIPSS).
Precision Nanostructuring: Femtosecond (320 fs, 515 nm) laser ablation successfully fabricated Low Spatial Frequency LIPSS (LSFL) with periods ranging from 360 nm to 420 nm.
Polarization Control: The orientation of the nanoripples is shown to rotate synchronously with the linear beam polarization, allowing for deterministic control over the surface grating vector.
Process Optimization: High pulse frequencies (>500 kHz) lead to negative thermal accumulation effects (enhanced graphitization and crack formation), highlighting the need for high-quality, thermally stable substrates like SCD/PCD for high-throughput processing.
Functional Outcome: Lateral Force Microscopy (LFM) confirms that the controlled LIPSS orientation effectively modulates nanoscale friction, demonstrating a pathway for advanced tribological applications.
6CCVD Relevance: The findings underscore the potential for using 6CCVD’s ultra-hard, thermally stable Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) substrates to extend this research into high-power, high-throughput laser functionalization regimes.

Technical Specifications

Extracted parameters and performance metrics from the femtosecond laser processing of Ti-DLN films.

Parameter	Value	Unit	Context
Material Base	Ti-DLN (a-C:H:Si:O)	N/A	Diamond-like Nanocomposite Film
Titanium Content	17-18	at.%	Metal doping concentration
Film Thickness	3-5	µm	Grown on Si(100) substrates
Laser Wavelength (λ)	515	nm	Visible Femtosecond Laser
Pulse Duration (τ)	320	fs	Ultra-short pulse regime
Peak Fluence (F)	0.32	J/cm²	Slightly above ablation threshold (F_th ~0.3 J/cm²)
Pulse Frequency (f)	100 kHz - 2 MHz	N/A	Tested range; optimal performance < 1 MHz
Scanning Pitch (V_s/f)	0.5	µm	Constant distance between pulses
LSFL Period (A) Range	360 ± 5 to 420 ± 10	nm	Dependent on polarization angle (0° to 90°)
LSFL Grating Depth	130 - 210	nm	Measured via AFM
Nanofriction Ratio (A)	Decreases from ~8 to ~2	N/A	Ratio of friction force on LIPSS vs. original film (F_LIPSS/F_film)
AFM Tip Load (F_load)	200	nN	Used for Lateral Force Microscopy (LFM)

Key Methodologies

The experimental procedure involved specialized material synthesis, precise femtosecond laser structuring, and advanced nanoscale characterization.

Material Growth (PACVD): Ti-DLN films (3-5 µm thick) were deposited onto Si(100) substrates using Plasma-Assisted Chemical Vapor Deposition (PACVD). The process involved simultaneous deposition from polymethylphenylsiloxane (PMPS) vapor plasma and magnetron sputtering of a titanium target in an argon atmosphere.
Laser Processing System: A SATSUMA HP2 femtosecond laser (λ = 515 nm, τ = 320 fs) was used. The beam was focused using a 100-mm telecentric objective to achieve a peak fluence of 0.32 J/cm².
High-Speed Scanning: A high-precision galvanometer scanner (intelliSCAN^se) controlled the scanning velocity (V_s) to maintain a constant scanning pitch (V_s/f = 0.5 µm) across pulse frequencies ranging from 100 kHz to 2 MHz.
Polarization Rotation: The linear polarization direction (E) was systematically rotated relative to the beam scanning direction (V_s) in 30° increments (0°, 30°, 60°, 90°) to study the effect on LIPSS orientation.
Structural Analysis: Surface morphology and LIPSS periods were determined using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) in tapping mode, and two-dimensional Fast Fourier Transform (FFT) analysis.
Tribological Analysis (LFM): Nanoscale friction was measured using contact-mode AFM (Lateral Force Microscopy) employing wear-resistant, diamond-coated Si probes (R_tip ~100 nm) at a constant load of 200 nN.

6CCVD Solutions & Capabilities

This research highlights the critical role of material properties—specifically thermal stability and hardness—in achieving high-quality, high-throughput laser functionalization. 6CCVD provides the ideal diamond material platforms to replicate and significantly extend these findings into industrial and extreme environment applications.

Research Requirement/Challenge	6CCVD Solution & Capability	Value Proposition for Replication/Extension
Material Limitation: Ti-DLN suffers from enhanced graphitization and cracking at high pulse frequencies (2 MHz) due to thermal accumulation.	Optical Grade SCD & High-Purity PCD: 6CCVD supplies MPCVD diamond with exceptional thermal conductivity (up to 2200 W/mK for SCD) and hardness (up to 100 GPa).	Enables High-Throughput: Our materials resist thermal degradation and graphitization, allowing researchers to utilize MHz and multi-MHz pulse frequencies for high-speed, high-quality LIPSS fabrication, overcoming the primary limitation identified in the paper.
Metal/Dopant Integration: The study relies on TiC nanocrystals for optical absorption and SPP excitation.	Custom Metalization & Doping: We offer internal metalization services (Au, Pt, Pd, Ti, W, Cu) and Boron Doping (BDD).	Researchers can transition from complex DLN nanocomposites to highly controlled, metal-functionalized SCD or PCD surfaces, providing cleaner interfaces for studying Surface Plasmon Polariton (SPP) dynamics and laser interaction mechanisms.
Surface Quality Requirement: Accurate LFM/tribology requires minimal surface defects.	Precision Polishing: SCD surfaces polished to Ra < 1 nm; Inch-size PCD polished to Ra < 5 nm.	Provides the ultra-smooth, defect-free starting surface essential for reproducible nanoscale structuring and accurate tribological measurements, ensuring data integrity in sensitive LFM experiments.
Substrate Size: Experiments used small 20 mm x 20 mm samples.	Custom Dimensions & Scale-Up: We supply PCD wafers up to 125 mm in diameter and SCD plates in custom sizes. Substrate thickness up to 10 mm.	Supports the transition from laboratory-scale research to pilot production and industrial applications requiring large-area functionalized diamond optics or tribological components.
Application: Nanotribology and friction control.	Material Supply: SCD and PCD are the ultimate materials for extreme tribological environments (high temperature, high load, corrosive media).	Enables the development of next-generation, friction-controlled diamond components for aerospace, high-speed bearings, and micro-electromechanical systems (MEMS).

Engineering Support

6CCVD’s in-house team of PhD material scientists specializes in the growth, processing, and functionalization of MPCVD diamond. We offer comprehensive engineering support to assist researchers in selecting the optimal diamond material (SCD, PCD, or BDD) and surface preparation (polishing, metalization) required to replicate or advance complex laser-material interaction projects, such as those involving LIPSS formation and nanoscale tribology.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

We study the properties of laser-induced periodic surface structures (LIPSS) formed on titanium-doped diamond-like nanocomposite (DLN) a-C:H:Si:O films during ablation processing with linearly-polarized beams of a visible femtosecond laser (wavelength 515 nm, pulse duration 320 fs, pulse repetition rates 100 kHz-2 MHz, scanning beam velocity 0.05-1 m/s). The studies are focused on (i) laser ablation characteristics of Ti-DLN films at different pulse frequencies and constant fluence close to the ablation threshold, (ii) effects of the polarization angle rotation on the properties of low spatial frequency LIPSS (LSFL), and (iii) nanofriction properties of the ‘rotating’ LIPSS using atomic force microscopy (AFM) in a lateral force mode. It is found that (i) all LSFL are oriented perpendicular to the beam polarization direction, so being rotated with the beam polarization, and (ii) LSFL periods are gradually changed from 360 ± 5 nm for ripples parallel to the beam scanning direction to 420 ± 10 nm for ripples formed perpendicular to the beam scanning. The obtained results are discussed in the frame of the surface plasmon polaritons model of the LIPSS formation. Also, the findings of the nanoscale friction behavior, dependent on the LIPSS orientation relative to the AFM tip scanning direction, are presented and discussed.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ma16020795

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