ABSTRACT The thin-film Cu-chalcopyrite-based solar cell technologies are becoming more attractive... more ABSTRACT The thin-film Cu-chalcopyrite-based solar cell technologies are becoming more attractive due to their lower cost and optimal performance. High efficiency of small cells might be maintained with the transition to larger areas if small segments are interconnected in series in order to reduce photocurrent in thin films and resistance losses. Interconnect formation is based on three step scribing processes and use of laser is thus crucial for performance of the device. For the first time we demonstrate the possibility to scribe the CZTSe thin-film solar cell structures with picosecond lasers. Investigations on the material lift-off effect in the CZTSe thin film were performed and the method was approved for the damage-free front-side scribing processes. Single pulse ablation and scribing experiments in the thin-film solar cell structures together with theoretical modeling of laser energy coupling in the complex CZTSe structure are presented. We found that the absorber layer removal process was triggered by a micro-explosive effect induced by high pressure of sublimated material due to temperature increase in molybdenum-CZTSe interface. This facilitated to minimize the remaining thermal effects since the laser-affected material was removed by thermo-mechanical process.
Laser micromachining has been proven an excellent technique for patterning many engineering mater... more Laser micromachining has been proven an excellent technique for patterning many engineering materials. The emitted photon energy from a UV laser is high enough to break the chemical bonds of the target reducing the heat effects on surrounding material. We ...
35th International Conference on Infrared, Millimeter, and Terahertz Waves, 2010
ABSTRACT Resonant mesh filters for THz region were fabricated using ultrashort pulse UV laser rad... more ABSTRACT Resonant mesh filters for THz region were fabricated using ultrashort pulse UV laser radiation. The arrays of cross-shaped holes were processed in the stainless steel foil and the molybdenum film on polyimide. The spectral performance of the filters was investigated experimentally and numerically.
Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XVII, 2012
ABSTRACT During the recent few years picosecond lasers have been proved as a reliable tool for mi... more ABSTRACT During the recent few years picosecond lasers have been proved as a reliable tool for microfabrication of diverse materials. We present results of our research on structuring of thin films and surfaces using the direct laser writing and the laser beam interference ablation techniques. The processes of micro-pattering were developed for metallic, dielectric films as well as complex multi-layer structures of thin-film solar cells as a way to manufacture frequency-selective surfaces, fine optical components and integrated series interconnects for photovoltaics. Technologies of nano-structuring of surfaces of advanced technical materials such as tungsten carbide were developed using picosecond lasers as well. Experimental work was supported by modeling and simulation of energy coupling and dissipation inside the layers. Selectiveness of the ablation process is defined by optical and mechanical properties of the materials, and selection of the laser wavelength facilitated control of the structuring process. Implementation of the technologies required fine adjustment of spatial distribution of laser irradiation, therefore both techniques are benefiting from shaping the laser beam with diffractive optical elements. Utilization of the whole laser energy included beam splitting and multi-beam processing.
ABSTRACT In this work we present the latest results in the application of multi-photon polymeriza... more ABSTRACT In this work we present the latest results in the application of multi-photon polymerization for tissue engineering, by fabricating microstructured artificial 3D scaffolds for stem cell growth. Microstructuring of large scale 3D scaffolds is investigated and the direct laser writing technique is supplemented by fabrication by multi-beam interference and micromolding of large scale structures. Within the limitation of our study, we conclude that the proposed nonlinear direct laser writing technique offers rapid and flexible fabrication of biomedical components with required shape, pore size and general porosity. The applications could target biostable and biodegradable implants applied for bone or tissue replacement as well as drug delivery or release agents.
ABSTRACT The thin-film Cu-chalcopyrite-based solar cell technologies are becoming more attractive... more ABSTRACT The thin-film Cu-chalcopyrite-based solar cell technologies are becoming more attractive due to their lower cost and optimal performance. High efficiency of small cells might be maintained with the transition to larger areas if small segments are interconnected in series in order to reduce photocurrent in thin films and resistance losses. Interconnect formation is based on three step scribing processes and use of laser is thus crucial for performance of the device. For the first time we demonstrate the possibility to scribe the CZTSe thin-film solar cell structures with picosecond lasers. Investigations on the material lift-off effect in the CZTSe thin film were performed and the method was approved for the damage-free front-side scribing processes. Single pulse ablation and scribing experiments in the thin-film solar cell structures together with theoretical modeling of laser energy coupling in the complex CZTSe structure are presented. We found that the absorber layer removal process was triggered by a micro-explosive effect induced by high pressure of sublimated material due to temperature increase in molybdenum-CZTSe interface. This facilitated to minimize the remaining thermal effects since the laser-affected material was removed by thermo-mechanical process.
Laser micromachining has been proven an excellent technique for patterning many engineering mater... more Laser micromachining has been proven an excellent technique for patterning many engineering materials. The emitted photon energy from a UV laser is high enough to break the chemical bonds of the target reducing the heat effects on surrounding material. We ...
35th International Conference on Infrared, Millimeter, and Terahertz Waves, 2010
ABSTRACT Resonant mesh filters for THz region were fabricated using ultrashort pulse UV laser rad... more ABSTRACT Resonant mesh filters for THz region were fabricated using ultrashort pulse UV laser radiation. The arrays of cross-shaped holes were processed in the stainless steel foil and the molybdenum film on polyimide. The spectral performance of the filters was investigated experimentally and numerically.
Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XVII, 2012
ABSTRACT During the recent few years picosecond lasers have been proved as a reliable tool for mi... more ABSTRACT During the recent few years picosecond lasers have been proved as a reliable tool for microfabrication of diverse materials. We present results of our research on structuring of thin films and surfaces using the direct laser writing and the laser beam interference ablation techniques. The processes of micro-pattering were developed for metallic, dielectric films as well as complex multi-layer structures of thin-film solar cells as a way to manufacture frequency-selective surfaces, fine optical components and integrated series interconnects for photovoltaics. Technologies of nano-structuring of surfaces of advanced technical materials such as tungsten carbide were developed using picosecond lasers as well. Experimental work was supported by modeling and simulation of energy coupling and dissipation inside the layers. Selectiveness of the ablation process is defined by optical and mechanical properties of the materials, and selection of the laser wavelength facilitated control of the structuring process. Implementation of the technologies required fine adjustment of spatial distribution of laser irradiation, therefore both techniques are benefiting from shaping the laser beam with diffractive optical elements. Utilization of the whole laser energy included beam splitting and multi-beam processing.
ABSTRACT In this work we present the latest results in the application of multi-photon polymeriza... more ABSTRACT In this work we present the latest results in the application of multi-photon polymerization for tissue engineering, by fabricating microstructured artificial 3D scaffolds for stem cell growth. Microstructuring of large scale 3D scaffolds is investigated and the direct laser writing technique is supplemented by fabrication by multi-beam interference and micromolding of large scale structures. Within the limitation of our study, we conclude that the proposed nonlinear direct laser writing technique offers rapid and flexible fabrication of biomedical components with required shape, pore size and general porosity. The applications could target biostable and biodegradable implants applied for bone or tissue replacement as well as drug delivery or release agents.
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Papers by Gediminas Raciukaitis