Filtern
Erscheinungsjahr
Dokumenttyp
Sprache
- Englisch (99)
Schlagworte
- Laser-induced periodic surface structures (LIPSS) (25)
- Femtosecond laser ablation (22)
- Femtosecond laser (15)
- Laser ablation (12)
- Laser processing (12)
- Surface functionalization (9)
- Radiation protection (8)
- Nanostructures (7)
- Silicon (7)
- Laser-induced X-ray emission (6)
- Laser beam effects (5)
- Laser-induced periodic surface structures (5)
- Chalcopyrite (4)
- Double-pulse experiments (4)
- Femtosecond laser processing (4)
- Friction (4)
- High-speed optical techniques (4)
- Laser-induced periodic surface structures, LIPSS (4)
- Microstructures (4)
- Steel (4)
- Tribology (4)
- Ultrafast optical techniques (4)
- Applications (3)
- Biofilms (3)
- Mach-Zehnder interferometer (3)
- Oxidation (3)
- Polymer (3)
- Silicon compounds (3)
- Surface morphology (3)
- Surface structure (3)
- Titanium (3)
- Titanium nitride (3)
- Ultrashort laser material interaction (3)
- Ultrashort laser pulses (3)
- Ultrashort pulsed laser (3)
- Wear (3)
- Auger electron spectroscopy (2)
- Cell adhesion (2)
- Dielectrics (2)
- Doping (2)
- Elemental semiconductors (2)
- Femtosecond laser patterning (2)
- Fluid transport (2)
- Indium phosphide (2)
- Laser damage (2)
- Laser-induced forward transfer (2)
- Laser-induced forward transfer (LIFT) (2)
- Laser-induced x-ray emission (2)
- Light concentration (2)
- Micro solar cell (2)
- Micro solar cells (2)
- Micro-concentrator solar cell (2)
- Niobium (2)
- Optical properties (2)
- Pacemaker (2)
- Photovoltaics (2)
- Polaritons (2)
- Scanning electron microscopy (2)
- Secondary hazard (2)
- Selective emitter (2)
- Semiconductors (2)
- Surface plasmon polaritons (2)
- Surface plasmons (2)
- Surface texture (2)
- Surface wetting (2)
- Titanium alloy (2)
- Ultra-short pulse laser processing (2)
- Ultrashort pulse laser processing (2)
- (LIPSS) (1)
- Ab initio calculations (1)
- Ablation (1)
- Absorber optimization (1)
- Aluminium (1)
- Amorphization (1)
- Anodic oxidation (1)
- Anodization (1)
- Antibacterial surfaces (1)
- Application (1)
- Atomic force microscopy (1)
- Bacterial adhesion (1)
- Bariumalumoborosilicate glass (1)
- Biofilm (1)
- Bioinspiration (1)
- Biomimetic surfaces (1)
- Biomometics (1)
- Bionic materials (1)
- Bug (1)
- CIGSe (1)
- CIGSe micro solar cells (1)
- Carrier excitation (1)
- Conduction bands (1)
- Copper indium gallium diselenide (CIGSe) (1)
- Copper-indium-gallium-diselenide (1)
- Crystallization (1)
- Cu(In,Ga)Se2 (1)
- CuInSe2 (1)
- Dentistry (1)
- Diffusion (1)
- Double-pulse (1)
- Editorial (1)
- Electromagnetic scattering (1)
- FS-laser ablation (1)
- Femtosecond (1)
- Femtosecond pulse laser (1)
- Fourier transforms (1)
- Fs-laser patterning (1)
- Fused silica (1)
- Hard X-ray photoelectron spectroscopy (HAXPES) (1)
- Heat affected zone (1)
- Indium (1)
- Indium islands (1)
- Industrial applications (1)
- Interferometer (1)
- LIFT (1)
- Laser Machining (1)
- Laser Processing (1)
- Laser materials processing (1)
- Laser safety (1)
- Laser-induced nanostructures (1)
- Laser-induced oxide layer (1)
- Laser-induced periodic surface strctures (LIPSS) (1)
- Laser-induced periodic surface strcutures (LIPSS) (1)
- Laser-modified surface (1)
- Lizard (1)
- Metals (1)
- Michelson interferometer (1)
- Microbial adhesion tests (1)
- Microbial adhesions (1)
- Microconcentrator solar cell (1)
- Micromachining (1)
- Molybdenum substrate (1)
- Multicrystalline silicon (1)
- Nanostrcutures (1)
- Ophthalmology (1)
- Optical breakdown (1)
- Optical coatings (1)
- Optical microscopy (1)
- Optics at surfaces (1)
- Photoelektron spectroscopy (1)
- Physical vapor deposition (1)
- Polarisation (1)
- Polycarbonate (1)
- Polyethylene (1)
- Polymethylmethacrylate (1)
- Protection housing (1)
- Pulse Laser (1)
- Pulse duration (1)
- Refractive index (1)
- Ripples (1)
- Scanning Auger electron microscopy (1)
- Second harmonic generation (SHG) (1)
- Semiconductor (1)
- Silica (1)
- Silicon nitride (1)
- Silicon oxide (1)
- Silicon solar cell (1)
- Simulation (1)
- Solar cell (1)
- Solid-state plasma (1)
- Spectroscopic imaging ellipsometry (1)
- Superconductivity (1)
- Surface plasmon polariton (1)
- Surface processing (1)
- Surface superconductivity (1)
- Thin films (1)
- Threshold of silicon (1)
- Ti6Al4V alloys (1)
- Time-of-flight secondary ion mass spectrometry (ToF-SIMS) (1)
- Time-resolved measurements (1)
- Time-resolved reflectivity measurements (1)
- Titanium nitride films (1)
- Ultrafast phenomena (1)
- Ultrashort lasers (1)
- Wetting (1)
- X-ray (1)
- X-ray emission (1)
- X-ray emission hazards (1)
- X-ray energies (1)
- X-ray photoelectron spectroscopy (1)
- X-ray spectrum (1)
- lossy materials (1)
- plasmon lifetime (1)
- surface plasmon polaritons (1)
Organisationseinheit der BAM
- 6 Materialchemie (35)
- 6.2 Material- und Oberflächentechnologien (35)
- 9 Komponentensicherheit (4)
- 9.5 Tribologie und Verschleißschutz (4)
- 6.7 Materialsynthese und Design (3)
- 4 Material und Umwelt (2)
- 4.1 Biologische Materialschädigung und Referenzorganismen (2)
- 5 Werkstofftechnik (1)
- 5.1 Mikrostruktur Design und Degradation (1)
- 6.1 Oberflächen- und Dünnschichtanalyse (1)
Paper des Monats
- ja (1)
Single Femtosecond Laser-Pulse-Induced Superficial Amorphization and Re-Crystallization of Silicon
(2021)
Superficial amorphization and re-crystallization of silicon in <111> and <100> orientation after irradiation by femtosecond laser pulses (790 nm, 30 fs) are studied using optical imaging and transmission electron microscopy. Spectroscopic imaging ellipsometry (SIE) allows fast data acquisition at multiple wavelengths and provides experimental data for calculating nanometric amorphous layer thickness profiles with micrometric lateral resolution based on a thin-film layer model. For a radially Gaussian laser beam and at moderate peak fluences above the melting and below the ablation thresholds, laterally parabolic amorphous layer profiles with maximum thicknesses of several tens of nanometers were quantitatively attained. The accuracy of the calculations is verified experimentally by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (STEM-EDX). Along with topographic information obtained by atomic force microscopy (AFM), a comprehensive picture of the superficial re-solidification of silicon after local melting by femtosecond laser pulses is drawn.
Ultrashort pulse laser processing can result in the secondary generation of unwanted X-rays if a critical laser irradiance of about 10^13 W/cm^2 is exceeded. Spectral X-ray emissions were investigated during the processing of tungsten and steel using three complementary spectrometers (based on CdTe and silicon drift detectors) simultaneously for the identification of a worst-case spectral scenario. Therefore, maximum X-ray photon energies were determined, and corresponding dose equivalent rates were calculated. An ultrashort pulse laser workstation with a pulse duration of 274 fs, a center wavelength of 1030 nm, pulse repetition rates between 50 kHz and 200 kHz, and a Gaussian laser beam focused to a spot diameter of 33 µm was employed in a single pulse and burst laser operation mode. Different combinations of laser pulse energy and repetition rate were utilized, keeping the average laser power constant close to the maximum power of 20 W. Peak irradiances ranging from 7.3 × 10^13 W/cm^2 up to 3.0 × 10^14 W/cm^2 were used. The X-ray dose equivalent rate increases for lower repetition rates and higher pulse energy if a constant average power is used. Laser processing with burst mode significantly increases the dose rates and the X-ray photon energies. A maximum X-ray photon energy of about 40 keV was observed for burst mode processing of tungsten with a repetition rate of 50 kHz and a peak irradiance of 3 × 10^14 W/cm^2.
Modern life and global communication would not be possible without technologically tailored thin films; they are omnipresent in daily life applications. In most cases, the films are deposited entirely at the carrying substrates in a specific processing step of the device or sample. In some cases, however, removal or modification must be performed locally, i.e., site-controlled and material selective through an additional laser processing step. For that ultrashort laser pulses with durations in the femtosecond and picosecond range can provide unique advantages and capabilities in industrially scalable schemes. This article reviews the current state of the research and corresponding industrial transfer related to the structuring of thin films by ultrashort pulsed lasers. It focuses on the pertinent historic developments, reveals the relevant physical and chemical effects, explores the ultimate limits, and discusses selected industrial and scientific applications.
Bacterial biofilms pose serious problems in medical and industrial settings. One of the major societal challenges lies in the increasing resistance of bacteria against biocides used in antimicrobial treatments, e.g., via overabundant use in medicine, industry, and agriculture or cleaning and disinfection in private households. Hence, new efficient bacteria-repellent strategies avoiding the use of biocides are strongly desired. One promising route to achieve bacteria-repellent surfaces lies in the contactless and aseptic large-area laser-processing of technical surfaces. Tailored surface textures, enabled by different laser-processing strategies that result in topographic scales ranging from nanometers to micrometers may provide a solution to this challenge. This article presents a current state-of-the-art review of laser-surface subtractive texturing approaches for controlling the biofilm formation for different bacterial strains and in different environments. Based on specific properties of bacteria and laser-processed surfaces, the challenges of anti-microbial surface designs are discussed, and future directions will be outlined.
X‑ray emission during the ablative processing of biological materials by ultrashort laser pulses
(2023)
The ablative laser processing with ultrashort pulsed laser beams may cause secondary emission of hazardous X-rays. While the effect has recently been proven to be considered in working safety regulations when processing technical materials, such as metals, the X-ray emission rates during the ablative processing of biological tissue materials are widely unexplored yet.
Therefore, biological materials like water, isotonic saline solution, pig eyes, and human teeth were ablated with ultrashort laser pulses of 1030 nm wavelength, 600 fs pulse duration and 5 kHz pulse repetition rate, aiming to mimic typical surgery situations. Simultaneously, in-situ X-ray dose rate measurements were performed at a short distance from the plasma to display potential X-ray emission. For all four studied biological materials, our measurements prove the secondary emission of laser-induced X-rays.
Unwanted X-ray emission in ultrashort pulse laser processing: From metallic to biological materials
(2023)
X-rays can be generated as an unwanted side effect during ultrashort pulse laser material processing of technical work pieces and even biological samples with laser intensities above 10^13 W/cm^2. First studies demonstrate the need to address this effect in industrial as well as in medical applications. This secondary hazard should be considered in work safety and risk assessment.
Surface nanostructures provide the possibility to create and tailor surface functionalities mainly via controlling their topography along with other chemical and physical material properties. One of the most appealing technologies for surface functionalization via micro- and nanostructuring is based on laser processing. This can be done either via direct contour-shaping of the irradiated material using a tightly focused laser beam or in a self-ordered way that allows employing larger laser beam diameters along with areal scanning to create a variety of laser-induced periodic surface structures (LIPSS). For the latter approach, particularly ultrashort pulsed lasers have recently pushed the borders across long-lasting limitations regarding the minimum achievable feature sizes and additionally boosted up the production times. This chapter reviews the plethora of recently investigated applications of LIPSS—for example, via imposing diffractive or plasmonic structural colors, the management of liquids and surface wetting properties, biomedical and bioinspired functionalities, beneficial effects in tribology for reducing friction and wear, the manipulation of optical scattering and absorption in photovoltaics, or the modification of magnetic or superconducting surface properties in other energy applications. The footprint of the LIPSS-based technology is explored in detail regarding the current state of industrialization, including an analysis of the market and associated LIPSS production costs.
Titanium and its alloys are known to allow the straightforward laser-based manufacturing of ordered surface nanostructures, so-called high spatial frequency laser-induced periodic surface structures (HSFL). These structures exhibit sub-100 nm spatial periods – far below the optical diffraction limit. The resulting surface functionalities are usually enabled by both, topographic and chemical alterations of the nanostructured surfaces. For exploring these effects, multi-method characterizations were performed here for HSFL processed on Ti–6Al–4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm, ≈1 ps pulse duration, 1–400 kHz) under different laser scan processing conditions, i.e., by systematically varying the pulse repetition frequency and the number of laser irradiation passes. The sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), tactile stylus profilometry, as well as near-surface chemical analyses hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (ToF-SIMS). This provides a quantification of the laser ablation depth, the geometrical HSFL characteristics and enables new insights into the depth extent and the nature of the non-ablative laser-induced near-surface oxidation accompanying these nanostructures. This allows to answer the questions how the processing of HSFL can be industrially scaled up, and whether the latter is limited by heat-accumulation effects.