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Graphite composite electrodes mixed with silicon are proposed as next generation anode material for high energy and high power applications. In order to overcome drawbacks caused by volume changes of silicon particles during electrochemical cycling and to maintain high specific capacities at enhanced C-rates, free-standing structures are generated on silicon/graphite electrodes by applying ultrafast laser ablation. Electrochemical properties are systematically investigated by means of galvanostatic measurements, cyclic voltammetry, and electrochemical impedance spectroscopy. Cells with structured electrodes exhibit improved battery performances and lithium-ion transport kinetics in comparison to cells with unstructured electrodes. Furthermore, the cells with structured electrodes exhibit a lower impedance at fully lithiated state. After cycling, post-mortem analysis is performed revealing that the mechanical stress within the electrodes and current collector can be significantly reduced due to laser generated free-standing structures.

In this study, the effect of laser induced periodic patterning of α-β titanium alloy (Ti-6Al-4V) developed by excimer laser (ArF, with a laser fluence of 2.4 J/cm2, a laser pulse repetition rate of 200 Hz and 50 laser pulses) and Fiber laser (using a power of 5 W, frequency of 80 kHz, scan speed of 800 mm/s and 2 times scanning) on its microstructure and corrosion behaviour have been investigated. The microstructure of the patterned surface shows a significant refinement of grains with the presence of α and β. A very low mass fraction of TiO2 was noticed when patterning was performed using ArF laser. A significant improvement in total surface energy (from 37 mN/m for Ti-6Al-4V to 41 mN/m for ArF laser patterned surface and 40 mN/m for Fiber laser patterned surface) and polar energy (from 11 mN/m for Ti-6Al-4V to 26 mN/m for ArF laser patterned surface and 24 mN/m for Fiber laser patterned surface) have been observed. Corrosion rate was reduced due to laser patterning (from 6.12 mm/year for as-received Ti-6Al-4V to 2.17 × 10−2 mm/year for ArF laser patterned and 1.68 × 10−2 mm/year for Fiber laser patterned Ti-6Al-4V surfaces). Laser surface patterning improved apatite deposition from 15% area coverage for Ti-6Al-4V to 34% and 33% area coverage for ArF and Fiber laser patterned surfaces, respectively.

Highlights • A prototype device combining a focused ion beam and a femtosecond laser is presented. • A case study of fabricating cantilevers for micro-mechanical tests into cold rolled tungsten foils was performed. • No coarsening of the ultra-fine grained microstructure was found after femtosecond laser ablation. • A sample array consisting of 100 cantilevers with a dimension of 420 ×60 ×25 μm3 was processed in only half an hour. The focused ion beam technique has become a standard tool for micro-mechanical sample preparation in the last decade due to its high precision and general applicability in material removal. Besides disadvantages such as possible ion damage and high operation costs especially the characteristically small removal rates represent a bottleneck for this application. In contrast, femtosecond lasers provide material removal rates orders of magnitude higher, with small or ideally without thermal impact on the surrounding material. Hence, a combination of these two methods offers an ideal tool for time-efficient, micrometer-sized sample preparation. A prototype implementing this idea is presented here in combination with a case study. Cantilevers with a length of several hundred micrometers were machined into 25 μm, 50 μm and 100 μm thick, cold rolled tungsten foils. Scanning electron microscopy analyses reveal the influence of laser parameters and different scanning routines on the resulting sample quality and the effect of the laser pulse length (femtoseconds versus nanoseconds) on the ultra-fine grained microstructure. Finally, the performance for unprecedented rapid sample preparation is demonstrated with a sample array consisting of 100 cantilevers with a dimension of 420 ×60 ×25 μm3 processed in only half an hour, opening completely new testing possibilities.

The interfacial instabilities, including side reactions due to electrolyte decompositions and Cobalt (Co) dissolutions, are the main detrimental processes at LiCoO2 cathode when a high-voltage window (>4.2 V) is applied. Nevertheless, cycling the cathode with a voltage above 4.2 V would deliver an increased gravimetric capacity, which is desired for high power battery operation. To address these drawbacks, we demonstrate a synergistic approach by manufacturing the three-dimensional high-temperature LiCoO2 electrodes (3D HT-LCO) using laser-microstructuring, laser-annealing and subsequent coating with polymerized C60 thin films (C60@3D HT-LCO) by plasma-assisted thermal evaporation. The C60@3D HT-LCO cathode delivers higher initial discharge capacity compared to its theoretical value, i.e. 175 mA h g−1 at 0.1 C with cut-off voltage of 3.0–4.5 V. This cathode combines the advantages of the 3D electrode architecture and an advanced C60 coating/passivation concept leading to an improved electrochemical performance, due to an increased active surface area, a decreased charge transfer resistance, a prevented Co dissolution into the electrolyte and a suppressed side reaction and electrolyte decomposition. This work provides a novel solution for other cathode materials having similar concerns in high potential regimes for application in lithium-ion microbatteries.

The present study concerns a detailed understanding of wear, corrosion and bio-activity behaviors of laser surface textured titanium alloy (Ti–6Al–4V) with line and dimple geometry developed by ArF excimer laser at a wavelength of 193 nm with a pulse length of 5 ns. The mechanical properties of the surface have been evaluated by measuring nano-hardness and wear resistance. The corrosion resistance property has also been evaluated in Hank's solution. The effect of laser surface texturing on bioactivity and cell attachment has also been studied. Laser surface texturing led to an increase in nano-hardness to a value of 4–6 GPa as compared to 2 GPa of the as-received Ti–6Al–4V. Furthermore, laser modified surfaces showed a significant increase in wear resistance and a marginal change in corrosion resistance. Textured surface shows a significant improvement in bioactivity in terms of calcium phosphate deposition rate in Hank's solution. XTT result shows, comparable cell viability of laser textured Ti–6Al–4V as that of as received Ti-alloy. Cell attachment study shows a reduced cell density in textured surface with a maximum reduction in dimple textured surface. Cells aligned themselves along the direction of texturing in linear textured surface.

Due to the excellent theoretical capacity, silicon-based electrodes have been extensively studied to develop high energy-density lithium-ion batteries (LIBs). Nevertheless, the large volume expansion and unfavorable interface seriously hamper its application, and the underlying physics behind are still unclear. In this work, using in-situ environment scanning electron microscopy (ESEM), the morphological evolution of composite silicon-graphite electrodes with different ionic liquids as electrolytes are compared in the range of 20 °C–60 °C. Surprisingly, combining the microstructure and surface reaction products from transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS), it finds out that the fully reaction of lithium-silicon does not generate huge volume expansion, while the side reaction between graphite and electrolyte decomposition products causes dramatic volume expansion and hinders the further lithiation of silicon. On the other hand, the electrolyte which is capable of rapidly releasing F− to form LiF-rich solid electrolyte interphase (SEI) is favorable to maintain the structure integrity and cycling performance. This work casts new understanding from the perspective of intrinsic reaction between electrode and ionic liquid electrolyte, which suggests that the practical application of silicon-based electrodes with appropriate electrolyte is a promising route for high energy-density LIBs.

The electrochemical performance of vanadium redox flow batteries (VRFBs) was enhanced via laser-patterned graphite felt (GF) electrodes. The laser-structured GF electrodes engineered via preparing a series of well-ordered microscopic channel structures with an average width of 200 μm, creating a three-dimensional carbon framework. The ultrafast laser patterning increased the porosity by 10%, as compared to pristine electrode. The analysis of the overpotential distribution using electrochemical impedance spectroscopy revealed that the electrode polarization involving charge transfer and diffusion resistance is strongly alleviated with the aid of carbon micro-perforation. The advanced design of laser-structured GF electrode also exhibits high rate capability, low internal resistance, and excellent cyclability. The improved performance was attributed to the synergistic effect involving (i) high electrochemically active surface area for rapid electrochemical reactions (i.e., V(II)/V(III) and V(IV)/V(V) redox couples) and (ii) excellent transport properties for facile electron/ion/species transport. The micro-scale channels created with the laser-ablation technique act as capillary structures and enabled homogeneous and rapid wetting of GF electrodes as formulated with the classical Washburn equation. The VRFB equipped with the laser-structured GF electrodes delivered a high discharge capacity with exceptional capacity retention upon extended cycling (>84.9%). Accordingly, the design of laser-structured electrode paves the pathway towards finely tuning the electrode internal microstructure for improved cyclability, durability, and capacity retention in various electrochemical energy storage/conversion devices (e.g. all-vanadium redox flow batteries).

In this study, we present the recrystallisation behaviour of heavily cold rolled tungsten sheets and show that the material recrystallises towards a single texture component, i.e. the rotated cube component {001} . This result is remarkable as it distinguishes from the classical concept of recrystallisation and is likely to have a strong impact in various fields in science and technology. The thermal stability of as-rolled tungsten sheets featuring a thickness reduction of 98% (i.e. 4.1 in the logarithmic notation) was investigated. Annealings were performed in a vacuum and in the temperature range of 400 °C (673 K) to 2000 °C (2273 K) for a time period of 6 min up to 500 h. The annealing-induced evolution of the microstructure is displayed by hardness (HV0.1) and electron backscatter diffraction (EBSD) measurements. The results show that after an annealing of 6 min at 800 °C (1073 K), the hardness drops from 666 ± 6.3 to 625 ± 7.9 HV0.1. The evolution of the hardness is fitted by classical kinetic models for recovery (logarithmic kinetics) and recrystallisation. The apparent activation energy of half of the hardness loss, EΔHV/2, was found to be 356 kJ/mol (3.69 eV), which can be associated with the activation energy of grain boundary diffusion in tungsten. Furthermore, the hardness data allows for the distinction between two stages. In stage I, the material rapidly develops an equiaxed grain structure by the break-up and spheroidisation of the high aspect ratio grains. We do not observe the formation of nuclei in the classical sense. Moreover, the recrystallisation processes can be described as grain growth. We suggest the dominant driving force to be the reduction of the internal stored energy. Finally, the transition from stage I to stage II is caused by the onset of abnormal grain growth.

The recycling of spent lithium-ion batteries has significant potential to benefit our society economically and environmentally as well as preserving raw materials. Although diverse process chains have been applied or under development to recycle batteries, a common, critical issue for battery recycling is the separation of the metallic current collector from the composite film of the electrode. In this study, inspired by the amazing controllable attachment and detachment ability of geckos’ foot-hairs, microscale near-surface architecture is designed on the interface between the current collector and the composite film in lithium-ion batteries, so that it displays controllable and directional adhesion, i.e., enhanced adhesion can be obtained during its lifetime to cope with the substantial volume changes of the composite film upon intercalation and deintercalation, whereas during recycling, the composite layer of the electrode can be easily peeled off from the current collector in a certain direction. This study is the first application of structural adhesives for the development of easy-to-recycle lithium-ion batteries. This technology can also be extended to other electronic products to avoid an ever-growing volume of electronic waste. The fundamental understanding on the interfacial adhesion and delamination mechanisms provides a scientific footing for the realization of next-generation easy-to-recycle electronics.

In the present study, a detailed study of the characterization of laser-surface textured titanium alloy (Ti–6Al–4V) with line and dimple geometry developed by using an ArF excimer laser operating at a wavelength of 193 nm with a pulse length of 5 ns is undertaken. The characterization of the textured surface (both the top surface and cross section) is carried out by scanning electron microscopy, electron back scattered diffraction (EBSD) technique and X-ray diffraction techniques. There is refinement of microstructure along with presence of titanium oxides (rutile, anatase and few Ti2O3 phase) in the textured surface as compared to as-received one. The area fractions of linear texture and dimple texture measured by image analysis software are 45% and 20%, respectively. The wettability is increased after laser texturing. The total surface energy is decreased due to linear (29.6 mN/m) texturing and increased due to dimple (67.6 mN/m) texturing as compared to as-received Ti–6Al–4V (37 mN/m). The effect of polar component is more in influencing the surface energy of textured surface.

Practical application of silicon anodes for lithium-ion batteries has been mainly hindered because of their low electrical conductivity and large volume change (ca. 300%) occurring during the lithiation and delithiation processes. Thus, the surface engineering of active particles (material design) and the modification of electrode structure (electrode design) of silicon are necessary to alleviate these critical limiting factors. Silicon/carbon core–shell particles (Si@C, material design) are prepared by the thermal decomposition and subsequent three-dimensional (3D) electrode structures (electrode design) with a channel width of 15 μm are incorporated using the laser ablation process. The electrochemical characteristics of 3D Si@C used as the anode material for lithium-ion batteries are investigated to identify the effects of material and electrode design. By the introduction of a carbon coating and the laser structuring, an enhanced performance of Si anode materials exhibiting high specific capacity (>1200 mAh g −1 over 300 cycles), good rate capability (1170 mAh g −1 at 8 A g −1 ), and stable cycling is achieved. The morphology of the core–shell active material combined with 3D channel architecture can minimize the volume expansion by utilizing the void space during the repeated cycling.

Porous LiMn 2 O 4 thick-film cathodes for Li-ion microbatteries are realized by laser-printing. The porous structure of the printed composite cathode consisting of active powder, binder, carbon black and graphite enables ionic and electronic transport through 50–60 μm thick electrodes due to its high intrinsic active surface area. In order to further improve the cycle stability and capacity retention of the laser-printed thick-film cathodes for discharging rates up to 1 C, laser-printed thick films are first calendered in a press and then structured using ultrafast femtosecond-laser radiation in order to form three-dimensional (3D) cathode architectures. It is shown that calendered/laser structured cathodes in the form of rectangular 3D grids exhibit discharge capacity retention of 68% at a 1 C rate, while calendered but unstructured cathodes retain only about 45% of their initial capacity at the same discharge rate. Overall, the improved discharge capacity retention and reduced degradation during later cycles can be attributed to the combination of increased electrical contact with shortened Li-ion pathways.

The structure and phase formations of radio frequency magnetron sputtered lithium manganese oxide thin films (Li 1.1 Mn 1.9 O 4 ) under ambient air were studied. The influence of laser annealing and furnace annealing, respectively, on the bulk structure and surface phases was compared by using ex-situ X-ray diffraction and Raman analysis. Laser annealing technique formed a dominant (440)-reflection, furnace annealing led to both, (111)- and (440)-reflections within a cubic symmetry (S.G. Fd3m (227)). Additionally, in-situ Raman and in-situ X-ray diffraction were applied for online detection of phase transformation temperatures. In-situ X-ray diffraction measurements clearly identified the starting temperature for the (111)- and (440)-reflections around 525 °C and 400 °C, respectively. The 2θ Bragg peak positions of the characteristic (111)- and (440)-reflections were in good agreement with those obtained through conventional furnace annealing. Laser annealing of lithium manganese oxide films provided a quick and efficient technique and delivered a dominant (440)-reflection which showed the expected electrochemical behavior of the well-known two-step de-/intercalation process of lithium-ions into the cubic spinel structure within galvanostatic testing and cyclic voltammetry.

The crystallization of lithium manganese oxide thin films prepared by radio frequency magnetron sputtering on stainless steel substrates under 10 Pa argon pressure is demonstrated by a laser annealing technique. Laser annealing processes were developed as a function of annealing time and temperature with the objective to form an electrochemically active lithium manganese oxide cathode. It is demonstrated, that laser annealing with 940 nm diode laser radiation and an annealing time of 2000 s at 600 °C delivers appropriate parameters for formation of a crystalline spinel-like phase. Characteristic features of this phase could be detected via Raman spectroscopy, showing the characteristic main Raman band at 627 cm−1. Within cyclic voltammetric measurements, the two characteristic redox pairs for spinel lithium manganese oxide in the 4 V region could be detected, indicating that the film was well-crystallized and de-/intercalation processes were reversible. Raman post-analysis of a cycled cathode showed that the spinel-like structure was preserved within the cycling process but mechanical degradation effects such as film cracking were observed via scanning electron microscopy. Typical features for the formation of an additional surface reaction layer could be detected using X-ray photoelectron spectroscopy.

It is expected that cathodes for lithium-ion batteries (LIB) composed out of nano-composite materials lead to an increase in power density of the LIB due to large electrochemically active surface areas but cathodes made of lithium manganese oxides (Li–Mn–O) suffer from structural instabilities due to their sensitivity to the average manganese oxidation state. Therefore, thin films in the Li–Mn–O system were synthesized by non-reactive radiofrequency magnetron sputtering of a spinel lithium manganese oxide target. For the enhancement of the power density and cycle stability, large area direct laser patterning using UV-laser radiation with a wavelength of 248 nm was performed. Subsequent laser annealing processes were investigated in a second step in order to set up a spinel-like phase using 940 nm laser radiation at a temperature of 680 °C. The interaction processes between UV-laser radiation and the material was investigated using laser ablation inductively coupled plasma mass spectroscopy. The changes in phase, structure and grain shape of the thin films due to the annealing process were recorded using Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The structured cathodes were cycled using standard electrolyte and a metallic lithium anode. Different surface structures were investigated and a significant increase in cycling stability was found. Surface chemistry of an as-deposited as well as an electrochemically cycled thin film was investigated via X-ray photoelectron spectroscopy.

A flexible and rapid surface functionalization of amorphous carbon films shows a great potential for various application fields such as biological surfaces and tribological systems. For this purpose, the combination of thin film deposition and subsequent laser material processing was investigated. Amorphous carbon layers doped with hydrogen were deposited on silicon wafers by reactive direct-current magnetron sputtering. Films with three different hydrogen contents were synthesized. Subsequent to the thin film deposition process, UV laser material processing at wavelengths of 193 nm or 248 nm was performed with respect to chemical surface modification and surface structuring on micro- and nanometer scale. Depending on structure size and laser-induced chemical surface modification the adjustment of the surface energy and wetting behaviour in a broad range from hydrophobic to hydrophilic was possible. The chemical modification and the ablation mechanisms near the ablation threshold were strongly influenced by the hydrogen content in amorphous carbon thin films. Structural and chemical information of the as-deposited and modified films was obtained by Raman spectroscopy, X-ray photoelectron spectroscopy and contact angle measurements.

The rapid manufacturing of functional capillary electrophoresis (CE) chips made of polymethylmethacrylate (PMMA) based on laser processing technologies including structuring, surface functionalization and packaging was investigated. CO2 laser-assisted micro-patterning was demonstrated to have a great potential for the fabrication of micro-channel devices and the production capability of CO2 laser processes has been extended to micro-channels less than 30 μm width. A high reproducibility of micro-channel geometry was attained. The average deviation between the fabricated cross-section areas and the desired cross-section areas of micro-channels was better than 3%. The packaging of these micro-structured transparent polymers was successfully established with a laser transmission welding technique using high-power diode laser radiation. CE-chips with channel widths of 150, 100 and 50μm were fabricated and electro-analytically characterized. For this purpose high frequency contactless conductivity detection (CCD) was established. Detection of small ions (Li+, Na+, and K+) with concentrations down to 0.1 × 10−3 mol/l was performed. Analytical results compare well to those obtained by conventional hot embossing and thermal welding. Furthermore, UV-assisted surface modification can be used to influence the micro-analytical performance. The pattern qualities and analytical results show that laser-based technologies have a great potential for application in flexible and cost-efficient production of polymeric microfluidic devices.

An appropriate choice of laser and process parameters enables new approaches for the fabrication of polymeric lab-on-chip devices with integrated functionalities. We will present our current research results in laser-assisted modification of polystyrene (PS) with respect to the fabrication of polymer devices for cell culture applications. For this purpose laser micro-patterning of PS and subsequent surface functionalization was investigated as function of laser and process parameters. A high power ArF-excimer laser radiation source with a pulse length of 19 ns as well as a high repetition ArF-excimer laser source with a pulse length of 5 ns were used in order to study the influence of laser pulse length on laser-induced surface oxidation. The change in surface chemistry was characterized by X-ray photoelectron spectroscopy and contact angle measurements. The difference between laser-assisted modification versus UV-lamp assisted modification was investigated. A photolytic activation of specific areas of the polymer surface and subsequent oxidization in oxygen or ambient air leads to a chemically modified polymer surface bearing carboxylic acid groups well-suited for controlled competitive protein adsorption or protein immobilization. Finally, distinct areas for cell growth and adhesion are obtained.

Laser-assisted patterning and modification of polystyrene (PS) was investigated with respect to applications in micro-fluidics and cell culture. For this purpose the wettability, the adsorption of proteins and the adhesion of animal cells were investigated as function of laser- and processing parameters. The change of surface chemistry was characterized by X-ray photoelectron spectroscopy. The local formation of chemical structures suitable for improved cell adhesion was realized on PS surfaces by UV laser irradiation. Above and below the laser ablation threshold two different mechanisms affecting cell adhesion were detected. In the first case the debris deposited on and along laser irradiated areas was responsible for improved cell adhesion, while in the second case a photolytic activation of the polymer surface including a subsequent oxidization in oxygen or ambient air is leading to a highly localized alteration of protein adsorption from cell culture media and finally to increased cell adhesion. Laser modifications of PS using suitable exposure doses and an appropriate choice of the processing gas (helium or oxygen) enabled a highly localized control of wetting. The dynamic advancing contact angle could be adjusted between 2° and 150°. The hydrophilic and hydrophobic behaviour are caused by chemical and topographical surface changes.

A microgripper of 2×3.9×0.1 mm3 size is presented consisting of a single device microfabricated from a shape memory alloy (SMA) thin sheet. The device consists of two integrated actuation units of a stress-optimized shape, which actuate in opposite directions and thus form an antagonistic pair. The fabrication procedure is reduced to one micromachining step of a rolled SMA sheet and subsequent bonding onto a substrate. The maximum displacement of the gripping jaws is 180 μm, the maximum gripping force 17 mN. For an electrical power of 22 mW, a response time of 32 ms is observed.

The patterning of thin and thick films (100 nm-2 μm) is performed with excimer laser radiation (A = 248 nm, τ = 20 ns, e max = 5 J/cm 2 ). The laser ablation is investigated for the film systems: Fe 0.6 Co 0.4 /SiO 2 -multilayers, Tb 0.4 Fe 0.6 /Fe 0.5 Co 0.5 multilayers and SiN y -layers. The ablation process strongly depends on the film material, film thickness, as well as on the laser parameters such as laser fluence and number of pulses. The influence of using a beam homogenizer on the ablation process is discussed. For applications in microsystem technology, the minimal attainable structure sizes and an appropriate choice of laser parameters are determined. The patterning of SiN y -layers for application in solar cells is investigated.

In laparoscopic surgery the endoscopic camera is mounted to the end of an integrated rod lens system and, therefore, the whole endoscopic camera system is rigid. To obtain a better overview of the operation area, different lens systems with certain angles of view (0, 32, 45 and 70°) are used. To avoid changing the camera system during an operation, a flexible distal end for a single chip camera was built. Therefore an exchange of cameras during an operation is no longer necessary. The flexible tip is made of a superelastic Nitinol (NiTi) tube and can be angled up to 90° inside the human body. The outer diameter of the superelastic tube is 10.5 mm and, as there are no tubes of that size commercially available on the market, it was manufactured using NiTi sheet material. To enable angles of up to 90°, new structures were cut into the NiTi tube with a Nd-YAG laser. To reduce the induced tension at the bending zones, shape optimization was performed using the ABAQUS FEM software. This allowed a reduction in tension of about 40% for the optimized structure. Consequently, bending cycles of up to 105 are now possible. The angles are adjusted with the thumb on the proximal end of the endoscope and a locking device at this end enables the angle to be kept at any position for any time.

A combination of microwave excitation and a mask projection scheme is applied for laser-assisted laterally structured etching of silicon. Different feed gases are used, such as CF 4 , either nonactivated or activated in a microwave discharge. With these gases well-defined structures are obtained with etch rates of 0.1 μm min −1 . Using a gas mixture of CF 4 and CCl 4 , the etching rate can be increased to 1 μm min −1 at room temperature. Smooth etched profiles can be achieved with laser fluences −2 . The etched Si surfaces are characterized by ex-situ X-ray photoelecton spectroscopy (XPS) and the gas phase reactions are investigated with quadrupole mass spectroscopy (QMS). The formation of ClF 3 or ClF is discussed as a critical step within the microwave-assisted laser dry etching (MALDE). The presence of these species correlates with high Si etch rates. A numerical solution of the one-dimensional heat flow equation is used to obtain the laser-induced surface temperature distribution. A numerical model of etching based on thermal evaporation gives etch rates many orders of magnitude smaller than the observed etch rates.

Pulsed laser deposition as a method of physical vapour deposition suitable for the deposition of thin films with complex structures and compositions is briefly reviewed. Excimer, Nd:YAG and CO 2 laser radiation are comparatively investigated as a function of laser parameters and processing variables in order to deposit thin ceramic (Al 2 O 3 , ZrO 2 , SiC, BN, BaTiO 3 , Y 1 Ba 2 Cu 3 O 7- ) films on various substrates (stainless steel, hard metal, Si, ZrO 2 , SrTiO 3 ). The methods of generating multicomponent and multilayer thin films, including the advantages of pulsed laser deposition, are described, indicating the great future application potential of pulsed laser deposition as a versatile and flexible method for the generation of films with complex compositions and structures. The laser parameters and processing variables achieve different vapour and/or plasma states, represented in the number, momentum and energy of the ensemble of species generated, which are used to deposit thin films with defined properties according to the application, in view of the mechanical-technical properties, tribological properties, fatigue and thermal barrier, illustrated by examples.

BN thin films were produced by pulsed laser deposition from a sintered BN target of the hexagonal structural phase using XeCl excimer laser radiation (λ = 308 nm) or pulsed CO 2 laser radiation (λ= 10.6 μm), and varying the process variables (laser fluence, N 2 partial pressure, target-substrate distance). Film properties such as chemical composition and crystal structure were studied by ex situ X-ray photoelectron, Auger electron and micro-Raman spectroscopies. Simple thermodynamic arguments are given to explain aspects of material removal from the target and film deposition. Films are generally composed of a fine-grained matrix in which particles 10–15 μm (λ = 308 nm) or 10–100 μm (λ= 10.6 μm) in size are embedded. In addition to BN, the films contain contaminants B 2 O 3 , metallic B, and a boron-oxynitride species, with the relative proportions dependent on the lateral position on the film surface. Micro-Raman spectra give evidence of amorphous and hexagonal structural phases of the BN matrix material.

BN thin films are grown on Si(100) substrates in a pulsed-laser deposition (PLD) process using a pulsed CO 2 laser, a hexagonal-phase BN (h-BN) target, and N 2 as processing gas. The effect of RF power coupled to the substrate during PLD is investigated. Films are analysed using optical microscopy and micro-Raman and X-ray photoemission spectroscopies. They are generally composed of a fine-grained matrix in which particles 10–100 μ m in size are embedded, with the morphology and chemical composition dependent on the lateral position on the film surface relative to the laser-induced plasma plume from the target. The roughness and contaminant concentration (B 2 O 3 , elemental B, and boron-oxynitride) are largest nearest the plasma-affected region. The matrix material over the entire film surface exhibits weak, broad spectral structures, indicating an amorphous structure. Certain regions have in addition h-BN Raman peaks that are shifted by up to 15 cm −1 to lower wave numbers relative to crystalline h-BN due to strain built in during deposition. No peaks characteristic of cubic BN or B 2 O 3 are found. Positions further from the plasma-affected region show stronger peaks, implying more crystalline order. The highest degree of crystallinity is reached for deposition with RF power applied to the substrate mainly during the laser pulses, as opposed to deposition with power applied between pulses or to deposition without RF power. In general, embedded particles have more intense Raman peaks than the surrounding matrix, comparable in strength to those of the target, suggesting that they arise from material ejection.

The tailoring of chemical, morphological, and mechanical surface properties with laser radiation is described on the basis of the understanding and control of photon-matter interaction. The removal of matter by thermal and non-thermal processes including etching, the deposition of multilayer thin films, and the photoresistless patterning by direct and indirect processing techniques are illustrated by examples.