TY - JOUR A1 - Baudach, Steffen A1 - Bonse, Jörn A1 - Kautek, Wolfgang T1 - Ablation experiments on polyimide with femtosecond laser pulses JF - Applied physics A N2 - Some applications of polymer films require the microstructuring of partly uneven substrates. This cannot be achieved by conventional photolithography, usually performed with ultraviolet short-pulse lasers (excimer, fourth harmonic Nd:YAG). When processing thermally sensitive or undoped polymers with low optical absorption, the use of femtosecond laser pulses can improve the ablation precision, also reducing the heat-affected zone. Therefore, a Ti:sapphire laser system was employed to perform ablation experiments on polyimide (PI). The irradiated areas were evaluated by means of optical and scanning electron microscopy. Highly oriented ripple structures, which are related to the polarization state of the laser pulses, were observed in the cavities. The relationship between the ablation threshold fluence and the number of laser pulses applied to the same spot is described in accordance with an incubation model. T2 - 5th International Conference on Laser Ablation ; COLA '99 CY - Göttingen, Germany DA - 1999-07-19 KW - Polyimide KW - Laser KW - Ablation KW - Femtosecond laser PY - 1999 DO - https://doi.org/10.1007/s003390051424 SN - 0947-8396 VL - 69 IS - 7 SP - S395 EP - S398 PB - Springer CY - Berlin AN - OPUS4-780 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Bonse, Jörn A1 - Kirner, Sabrina V. A1 - Krüger, Jörg ED - Sugioka, K. T1 - Laser-Induced Periodic Surface Structures (LIPSS) T2 - Handbook of Laser Micro- and Nano-Engineering N2 - Laser-induced periodic surface structures (LIPSS) are a universal phenomenon and can be generated on almost any material by irradiation with linearly polarized radiation. This chapter reviews the current state in the field of LIPSS, which are formed in a “self-ordered” way and are often accompanying materials processing applications. LIPSS can be produced in a single-stage process and enable surface nanostructuring and, in turn, adaption of optical, mechanical, and chemical surface properties. Typically, they feature a structural size ranging from several micrometers down to less than 100 nm and show a clear correlation with the polarization direction of the light used for their generation. Various types of LIPSS are classified, relevant control parameters are identified, and their material-specific formation mechanisms are analyzed for different types of inorganic solids, i.e., metals, semiconductors, and dielectrics. Finally, technological applications featuring surface functionalization in the fields of optics, fluidics, medicine, and tribology are discussed. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser KW - Laser ablation KW - Microstructures KW - Nanostrcutures PY - 2021 SN - 978-3-030-63646-3 (Print) SN - 978-3-030-63647-0 (Online) DO - https://doi.org/10.1007/978-3-030-63647-0_17 SP - 879 EP - 936 PB - Springer-Nature Switzerland AG CY - Cham ET - 1 AN - OPUS4-53728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Rudenko, A. A1 - Déziel, J.-L. A1 - Florian, Camilo A1 - Krüger, Jörg A1 - Siegel, J. A1 - Colombier, J.-P. T1 - The role of electromagnetic scattering in the formation of laser-induced periodic surface structures N2 - Laser-induced periodic surface structures (LIPSS) are a universal phenomenon that is accompanying laser materials processing. These surface nanostructures pave a simple way for surface functionalization with numerous applications in optics, fluidics, tribology, medicine, etc. During the last decade remarkable experimental and theoretical improvements in understanding of their formation mechanisms were obtained - all pointing toward polarization-dependent energy deposition by absorption of optical radiation that is scattered at the surface roughness and interfering with the laser beam. This contribution reviews the current state-of-the-art on the role of electromagnetic scattering in the formation of LIPSS by ultrashort laser pulses. Special attention is drawn to recent finite-difference time-domain (FDTD) calculations that allow to visualize the radiation patterns formed in the vicinity of the sample surface and to the impact of a thin superficial laser-induced oxidation layer. T2 - E-MRS Spring Meeting 2021 CY - Online meeting DA - 31.05.2021 KW - Laser-induced periodic surface structures (LIPSS) KW - Optical scattering KW - Oxidation KW - Femtosecond laser PY - 2021 AN - OPUS4-52729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Surface nanotexturing by ultrashort laser pulses N2 - The presentation reviews the BAM activities in the field of surface processing by ultrashort laser pulses. A focus is laid on the generation of laser-induced periodic surface structures (LIPSS) which allow various surface functionalizations for applications in optics, tribology, liquid management, and medicine. T2 - Photonics Days Berlin Brandenburg 2022 CY - Berlin, Germany DA - 05.10.2022 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser KW - Surface functionalization PY - 2022 AN - OPUS4-55921 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Seuthe, T. A1 - Grehn, M. A1 - Eberstein, M. A1 - Rosenfeld, A. A1 - Mermillod-Blondin, A. T1 - Time-resolved microscopy of fs-laser-induced heat flows in glasses JF - Applied Physics A N2 - Time-resolved phase-contrast microscopy is employed to visualize spatio-temporal thermal transients induced by tight focusing of a single Ti:sapphire fs-laser pulse into a solid dielectric sample. This method relies on the coupling of the refractive index change and the sample temperature through the thermo-optic coefficient dn/dT. The thermal transients are studied on a timescale ranging from 10 ns up to 0.1 ms after laser excitation. Beyond providing direct insights into the laser–matter interaction, analyzing the results obtained also enables quantifying the local thermal diffusivity of the sample on a micrometer scale. Studies conducted in different solid dielectrics, namely amorphous fused silica (a-SiO2), a commercial borosilicate glass (BO33, Schott), and a custom alkaline earth silicate glass (NaSi66), illustrate the applicability of this approach to the investigation of various glassy materials. KW - Femtosecond laser KW - Phase-contrast microscopy KW - Heat diffusion KW - Glasses PY - 2018 DO - https://doi.org/10.1007/s00339-017-1465-5 SN - 0947-8396 SN - 1432-0630 VL - 124 IS - 1 SP - 60, 1 EP - 6 PB - Springer-Verlag AN - OPUS4-43739 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Kirner, Sabrina V. A1 - Spaltmann, Dirk A1 - Krüger, Jörg T1 - Laser-induced Periodic Surface Structures: Fundamentals & Applications N2 - During the past few years significantly increasing research activities in the field of laser-induced periodic surface structures (LIPSS, ripples) have been reported since the generation of LIPSS in a single-step process provides a simple way of surface nanostructuring towards a control of optical, mechanical or chemical surface properties. In this contribution the current research state in this field is reviewed. The formation of LIPSS upon irradiation of metals, semiconductors and dielectrics by multiple linearly polarized Ti:sapphire fs-laser pulses (30-150 fs) is studied experimentally and theoretically. Different types of LIPSS with periods even below 100 nm can be generated. Their dynamics and formation mechanisms are analyzed and identified in ultrafast optical experiments. Complementing theoretical calculations of the laser-induced carrier dynamics address transient changes of the optical properties of the irradiated materials and reveal the importance of surface plasmon polaritons in the early stage of LIPSS formation. Various applications of these nanostructures are outlined. T2 - Workshop "Materialbearbeitung mit gepulsen Lasern" der Universität Stuttgart CY - Hirschegg, Austria DA - 13.02.2018 KW - Laser-induced periodic surface structures (LIPSS) KW - Laser ablation KW - Surface functionalization KW - Femtosecond laser PY - 2018 AN - OPUS4-44295 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heidmann, B. A1 - Andree, Stefan A1 - Levcenko, S. A1 - Unold, T. A1 - Abou-Ras, D. A1 - Schäfer, N. A1 - Bonse, Jörn A1 - Krüger, Jörg A1 - Schmid, M. T1 - Fabrication of regularly arranged chalcopyrite micro solar cells via femtosecond laser-induced forward transfer for concentrator application JF - ACS Applied Energy Materials N2 - A laser-based bottom-up technique for the fabrication of Cu(In,Ga)Se2 (CIGSe) micro solar cells is presented. We use femtosecond laser-induced forward transfer (LIFT) to transport a metallic precursor composed of copper, indium, and gallium onto a molybdenum back contact layer on a glass substrate. A CIGSe absorber forms by subsequent selenization. An array of micro absorbers with defined spacing is fabricated to solar cells and characterized under concentrated light illumination. The solar cell array exhibited a conversion efficiency of 1.4‰ at 1 sun as well as a significant efficiency enhancement of 68% rel. under 20-fold concentration. This work demonstrates the possibility of directly grown micrometer-sized solar cells based on chalcogenide absorber layers, enabling effective material usage. KW - Micro solar cells KW - Light concentration KW - LIFT KW - Chalcopyrite KW - Femtosecond laser PY - 2018 DO - https://doi.org/10.1021/acsaem.7b00028 SN - 2574-0962 VL - 1 IS - 1 SP - 27 EP - 31 PB - ACS CY - Washington, DC AN - OPUS4-43999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Pentzien, Simone A1 - Dittmar, G. A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - X-ray emission as a potential hazard during ultrashort pulse laser material processing JF - Applied physics A N2 - In laser machining with ultrashort laser pulses unwanted X-ray radiation in the keV range can be generated when a critical laser intensity is exceeded. Even if the emitted X-ray dose per pulse is low, high laser repetition rates can lead to an accumulation of X-ray doses beyond exposure safety limits. For 925 fs pulse duration at a center wavelength of 1030 nm, the X-ray emission was investigated up to an intensity of 2.6 × 10^14 W/cm2. The experiments were performed in air with a thin disk laser at a repetition rate of 400 kHz. X-ray spectra and doses were measured for various planar target materials covering a wide range of the periodic table from aluminum to tungsten. Without radiation shielding, the measured radiation doses at this high repetition rate clearly exceed the regulatory limits. Estimations for an adequate radiation shielding are provided. KW - Laser-induced X-ray emission KW - Ultrashort laser material interaction KW - Femtosecond laser KW - Radiation protection PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-448431 DO - https://doi.org/10.1007/s00339-018-1828-6 SN - 0947-8396 SN - 1432-0630 VL - 124 IS - 6 SP - Article 407, 1 EP - 8 PB - Springer AN - OPUS4-44843 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Bonse, Jörn A1 - Kirner, Sabrina V. A1 - Krüger, Jörg ED - Sugioka, K. T1 - Laser-induced periodic surface structures (LIPSS) T2 - Handbook of laser micro- and nano-engineering N2 - Laser-induced periodic surface structures (LIPSS) are a universal phenomenon and can be generated on almost any material by irradiation with linearly polarized radiation. This chapter reviews the current state in the field of LIPSS, which are formed in a “self-ordered” way and are often accompanying materials processing applications. LIPSS can be produced in a single-stage process and enable surface nanostructuring and, in turn, adaption of optical, mechanical, and chemical surface properties. Typically, they feature a structural size ranging from several micrometers down to less than 100 nm and show a clear correlation with the polarization direction of the light used for their generation. Various types of LIPSS are classified, relevant control parameters are identified, and their material-specific formation mechanisms are analyzed for different types of inorganic solids, i.e., metals, semiconductors, and dielectrics. Finally, technological applications featuring surface functionalization in the fields of optics, fluidics, medicine, and tribology are discussed. KW - Laser-induced periodic surface structures (LIPSS) KW - Laser ablation KW - Femtosecond laser KW - Nanostructures KW - Microstructures PY - 2020 SN - 978-3-319-69537-2 DO - https://doi.org/10.1007/978-3-319-69537-2_17-1 SP - 1 EP - 59 PB - Springer Nature CY - Cham, Switzerland ET - 1 AN - OPUS4-51332 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - A survey of surface functionalization through laser-induced periodic surface structures N2 - Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon that can be observed on almost any material after the irradiation by linearly polarized laser beams, particularly when using ultrashort laser pulses with durations in the femtosecond to picosecond range. During the past few years significantly increasing research activities have been reported in the field of LIPSS, since their generation in a single-step process provides a simple way of nanostructuring and surface functionalization towards the control of optical, mechanical, biological, or chemical surface properties. In this contribution the mechanisms of formation and current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, the advancement of medical pacemakers, and the improvement of the tribological performance of nanostructured metal surfaces. T2 - Seminar, ALPhANOV - Centre Technologique Optique et Lasers CY - Talence, France DA - 07.06.2019 KW - Laser-induced periodic surface structures, LIPSS KW - Surface functionalization KW - Applications KW - Femtosecond laser PY - 2019 AN - OPUS4-48199 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Florian, Camilo A1 - Kirner, Sabrina V. A1 - Krüger, Jörg T1 - Femtosecond laser-induced periodic surface structures: from light localization to applications N2 - This presentation reviews the current state in the field of Laser-induced Periodic Surface Structures (LIPSS). These surface nanostructures are a universal phenomenon and can be generated on almost any material by irradiation with intense linearly polarized laser radiation. LIPSS are formed in a “self-ordered” way and are often accompanying material processing applications. They can be produced following a single-step process and enable surface functionalization through the adaption of optical, mechanical and chemical surface properties. Their structural sizes typically range from several micrometers down to less than 100 nanometers exhibiting a clear correlation with the polarization direction of the laser radiation. Various types of surface structures are classified, relevant control parameters are identified, and their material specific formation mechanisms are analyzed for different types of inorganic solids, i.e., metals, semiconductors, and dielectrics, through time-resolved optical experiments and theoretical simulations. Finally, technological applications featuring surface functionalization in the fields of optics, fluidics, medicine, and tribology are discussed. T2 - International Conference on Advanced Laser Technologies (ALT'19) CY - Prague, Czech Republic DA - 15.09.2019 KW - Laser-induced periodic surface structures, LIPSS KW - Femtosecond laser KW - Surface functionalization KW - Electromagnetic scattering PY - 2019 AN - OPUS4-49098 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ringleb, F. A1 - Eylers, K. A1 - Teubner, T. A1 - Boeck, T. A1 - Symietz, Christian A1 - Bonse, Jörn A1 - Andree, Stefan A1 - Krüger, Jörg A1 - Heidmann, B. A1 - Schmid, M. A1 - Lux-Steiner, M. T1 - Regularly arranged indium islands on glass/molybdenum substrates upon femtosecond laser and physical vapor deposition processing JF - Applied Physics Letters N2 - A bottom-up approach is presented for the production of arrays of indium islands on a molybdenum layer on glass, which can serve as micro-sized precursors for indium compounds such as copper-indium-gallium-diselenide used in photovoltaics. Femtosecond laser ablation of glass and a subsequent deposition of a molybdenum film or direct laser processing of the molybdenum film both allow the preferential nucleation and growth of indium islands at the predefined locations in a following indium-based physical vapor deposition (PVD) process. A proper choice of laser and deposition parameters ensures the controlled growth of indium islands exclusively at the laser ablated spots. Based on a statistical analysis, these results are compared to the non-structured molybdenum surface, leading to randomly grown indium islands after PVD. KW - Femtosecond laser KW - Physical vapor deposition KW - Indium KW - Molybdenum substrate KW - Microconcentrator solar cell PY - 2016 DO - https://doi.org/10.1063/1.4943794 SN - 0003-6951 VL - 108 IS - 11 SP - 111904-1 EP - 111904-4 AN - OPUS4-35602 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Laser-induced periodic surface structures: from nanoscaled light localization to applications N2 - In this contribution the current state in the field of Laser-Induced Periodic Surface Structures (LIPSS) is reviewed. This includes the mechanisms of formation and current applications, particularly the colorization of technical surfaces, the control of surface wetting properties, the tailoring of surface colonization by bacterial biofilms, and the improvement of the tribological performance of nanostructured metal surfaces. T2 - PHOTONICA 2019 - The Seventh International School and Conference on Photonics CY - Belgrade, Serbia DA - 26.08.2019 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser KW - Surface functionalization PY - 2019 UR - http://www.photonica.ac.rs/docs/PHOTONICA2019-Book_of_abstracts.pdf AN - OPUS4-48836 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - The influence of processing parameters on X‑ray emission during ultra‑short pulse laser machining JF - Applied Physics A N2 - During ultra-short laser material processing at high laser pulse repetition rates unwanted X-ray radiation can be generated in a quantity that may constitute a potential risk for health. An adequate X-ray radiation protection requires a thoroughly understanding of the influence of the laser processing parameters on the generation of X-ray radiation. In the present work, the generated X-ray dose during laser machining was investigated in air for varying beam scanning conditions at a pulse duration of 925 fs, a center wavelength of 1030 nm and a laser peak intensity of 2.6 × 10^14 W/cm^2. The X-ray radiation dose and the corresponding spectral X-ray emission were investigated in dependence on the laser’s pulse repetition rate and on the beam scanning speed. The results show a strong dependence of the X-ray emission on these laser processing parameters. KW - Laser-induced X-ray emission KW - Ultrashort laser material interaction KW - Femtosecond laser KW - Radiation protection PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486441 DO - https://doi.org/10.1007/s00339-019-2827-y SN - 0947-8396 SN - 1432-0630 VL - 125 IS - 8 SP - 570, 1 EP - 8 PB - Springer AN - OPUS4-48644 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Kirner, Sabrina V. A1 - Höhm, S. A1 - Derrien, Thibault J.-Y. A1 - Krüger, Jörg T1 - Laser-induced periodic surface nanostructures N2 - This presentation reviews the current state in the field of Laser-induced Periodic Surface Structures (LIPSS). These surface nanostructures are a universal phenomenon and can be generated on almost any material by irradiation with intense linearly polarized radiation. LIPSS are formed in a “self-ordered” way and are often accompanying material processing applications. They can be produced in a single-step process and enable surface functionalization through the adaption of optical, mechanical and chemical surface properties. Their structural sizes typically range from several micrometers down to less than 100 nanometers and show a clear correlation with the polarization direction of the laser radiation. Various types of surface structures are classified, relevant control parameters are identified, and their material specific formation mechanisms are analyzed for different types of inorganic solids, i.e., metals, semiconductors, and dielectrics, through time-resolved optical experiments and theoretical simulations. Finally, technological applications featuring surface functionalization in the fields of optics, fluidics, medicine, and tribology are discussed. T2 - International Symposium “Fundamentals of Laser Assisted Micro- and Nanotechnologies” (FLAMN-19) CY - St. Petersburg, Russia DA - 30.06.2019 KW - Laser-induced periodic surface structures, LIPSS KW - Femtosecond laser KW - Surface functionalization KW - Ultrafast scattering PY - 2019 AN - OPUS4-48420 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Bonse, Jörn A1 - Kirner, Sabrina V. A1 - Krüger, Jörg ED - Sugioka, K. T1 - Laser-induced periodic surface structures (LIPSS) T2 - Handbook of laser micro- and nano-engineering N2 - Laser-induced periodic surface structures (LIPSS) are a universal phenomenon and can be generated on almost any material by irradiation with linearly polarized radiation. This chapter reviews the current state in the field of LIPSS, which are formed in a “self-ordered” way and are often accompanying materials processing applications. LIPSS can be produced in a single-stage process and enable surface nanostructuring and, in turn, adaption of optical, mechanical, and chemical surface properties. Typically, they feature a structural size ranging from several micrometers down to less than 100 nm and show a clear correlation with the polarization direction of the light used for their generation. Various types of LIPSS are classified, relevant control parameters are identified, and their material-specific formation mechanisms are analyzed for different types of inorganic solids, i.e., metals, semiconductors, and dielectrics. Finally, technological applications featuring surface functionalization in the fields of optics, fluidics, medicine, and tribology are discussed. KW - Femtosecond laser KW - Laser ablation KW - Laser-induced periodic surface structures (LIPSS) KW - Microstructures KW - Nanostructures PY - 2021 SN - 978-3-319-69537-2 DO - https://doi.org/10.1007/978-3-319-69537-2_17-2 SP - 1 EP - 59 PB - Springer Nature CY - Cham, Switzerland ET - 2 AN - OPUS4-51493 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Florian, Camilo A1 - Fischer, Daniel A1 - Freiberg, K. A1 - Duwe, M. A1 - Sahre, Mario A1 - Schneider, S. A1 - Hertwig, Andreas A1 - Krüger, Jörg A1 - Rettenmayr, M. A1 - Beck, Uwe A1 - Undisz, A. A1 - Bonse, Jörn T1 - Single Femtosecond Laser-Pulse-Induced Superficial Amorphization and Re-Crystallization of Silicon JF - Materials N2 - 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. KW - Femtosecond laser KW - Silicon KW - Amorphization KW - Crystallization KW - Spectroscopic imaging ellipsometry PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523687 UR - https://www.mdpi.com/1996-1944/14/7/1651 DO - https://doi.org/10.3390/ma14071651 SN - 1996-1944 VL - 14 IS - 7 SP - 1651-1 EP - 1651-21 PB - MDPI AG CY - Basel, Switzerland AN - OPUS4-52368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Andree, Stefan A1 - Heidmann, B. A1 - Ringleb, F. A1 - Eylers, K. A1 - Bonse, Jörn A1 - Boeck, T. A1 - Schmid, M. A1 - Krüger, Jörg T1 - Femtosecond laser pulses for photovoltaic bottom-up strategies T2 - Tagungsband zur 10. Mittweidaer Lasertagung N2 - A promising technology in photovoltaics is based on micro-concentrator solar cells, where the photovoltaic active area is realized as an array of sub-millimeter sized cells onto which the incident light is focused via microlenses. This approach allows to increase the cell efficiency and to realize much more compact modules compared to macroscopic concentrator devices. At the same time, expensive raw materials can be saved, which is of interest, for example, with respect to indium in the case of copper-indium-gallium-diselenide (CIGSe) thin film solar cells. Two methods to produce micro-sized precursors of CIGSe absorbers on molybdenum are presented using 30-fs laser pulses at 790 nm wavelength. On the one hand, a multi pulse surface structuring of the molybdenum film or the underlying glass substrate and a subsequent physical vapor deposition were used for a site-selective aggregation of indium droplets. On the other hand, a single pulse laser-induced forward transfer was utilized to selectively deposit combined copper-indium precursor pixels on the molybdenum back contact of the solar cell. Post-processing (selenization, isolation, contacting) of the laser-generated micro-sized precursors results in functional CIGSe solar cells. T2 - 10. Mittweidaer Lasertagung CY - Mittweida, Germany DA - 16.11.2017 KW - Copper indium gallium diselenide (CIGSe) KW - Micro solar cell KW - Femtosecond laser KW - Laser ablation KW - Laser-induced forward transfer (LIFT) PY - 2017 SN - 1437-7624 VL - 2 SP - 1 EP - 4 PB - Hochschule Mittweida CY - Mittweida AN - OPUS4-42988 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seuthe, T. A1 - Mermillod-Blondin, A. A1 - Grehn, M. A1 - Bonse, Jörn A1 - Wondraczek, L. A1 - Eberstein, M. T1 - Structural relaxation phenomena in silicate glasses modifed by irradiation with femtosecond laser pulses JF - Scientific Reports N2 - Structural relaxation phenomena in binary and multicomponent lithium silicate glasses were studied upon irradiation with femtosecond (fs) laser pulses (800 nm central wavelength, 130 fs pulse duration) and subsequent thermal annealing experiments. Depending on the annealing temperature, micro-Raman spectroscopy analyses evidenced different relaxation behaviours, associated to bridging and non-bridging oxygen structures present in the glass network. The results indicate that the mobility of lithium ions is an important factor during the glass modification with fs-laser pulses. Quantitative phase contrast imaging (spatial light interference microscopy) revealed that these fs-laser induced structural modifications are closely related to local changes in the refractive index of the material. The results establish a promising strategy for tailoring fs-laser sensitivity of glasses through structural mobility. KW - Femtosecond laser KW - Silicate glasses KW - Raman spectroscopy KW - Structural relaxation KW - Refractive index PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-393045 DO - https://doi.org/10.1038/srep43815 SN - 2045-2322 VL - 7 SP - 43815, 1 EP - 43815, 10 PB - Nature Publishing Group CY - London, UK AN - OPUS4-39304 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epperlein, Nadja A1 - Menzel, Friederike A1 - Schwibbert, Karin A1 - Koter, Robert A1 - Bonse, Jörn A1 - Sameith, Janin A1 - Krüger, Jörg A1 - Toepel, Jörg T1 - Influence of femtosecond laser produced nanostructures on biofilm growth on steel JF - Applied Surface Science N2 - Biofilm formation poses high risks in multiple industrial and medical settings. However, the robust nature of biofilms makes them also attractive for industrial applications where cell biocatalysts are increasingly in use. Since tailoring material properties that affect bacterial growth or its inhibition is gaining attention, here we focus on the effects of femtosecond laser produced nanostructures on bacterial adhesion. Large area periodic surface structures were generated on steel surfaces using 30-fs laser pulses at 790 nm wavelength. Two types of steel exhibiting a different corrosion resistance were used, i.e., a plain structural steel (corrodible) and a stainless steel (resistant to corrosion). Homogeneous fields of laser-induced periodic surface structures (LIPSS) were realized utilizing laser fluences close to the ablation threshold while scanning the sample under the focused laser beam in a multi-pulse regime. The nanostructures were characterized with optical and scanning electron microscopy. For each type of steel, more than ten identical samples were laser-processed. Subsequently, the samples were subjected to microbial adhesion tests. Bacteria of different shape and adhesion behavior (Escherichia coli and Staphylococcus aureus) were exposed to laser structures and to polished reference surfaces. Our results indicate that E. coli preferentially avoids adhesion to the LIPSS-covered areas, whereas S. aureus favors these areas for colonization. KW - Laser-induced periodic surface structures KW - Femtosecond laser KW - Steel KW - Biofilms KW - Microbial adhesion tests PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433217305470 DO - https://doi.org/10.1016/j.apsusc.2017.02.174 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 420 EP - 424 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-40565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -