- 标题
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Functionalizing Window Coatings with Luminescence Centers by Combinatorial Sputtering of Scatter-Free Amorphous SiAlON:Eu2+ Thin Film Composition Libraries
摘要： SiAlON window coatings are applied on an industrial scale to achieve e.g. scratch-resistance and anti-reflection. Doping these SiAlONs with rare-earths adds luminescent functionality, which could be applied in photovoltaics. By using a combinatorial reactive sputtering approach, an amorphous thin film composition library with a Si:Al ratio from 0:062 : 1 to 3:375 : 1 and a Eu doping from 4:8 at:% to 26 at:% is created. This library uniquely combines high absorption, strong emission and absence of light scattering. By combining position-dependent EDX measurements with transmission and emission spectra, properties like the index of refraction, absorption strength, emission wavelength and decay times of the library can directly be related to the composition. Throughout the library, an index of refraction of 1:63 ± 0:03 is observed, typical for a film with low nitrogen content. The library also shows a large absorption coefficient of 1294 ± 8 cm?1 at:%?1. Laser-excited emission spectra show that the library has a strong redshift from 500 nm to 550 nm with increasing Al concentration. An increase in Eu concentration also causes a shift of the emission to red. Decay spectra show that a high degree of Si greatly improves the luminescence intensity. These functionalized SiAlON coatings can be of great interest for transparent and scatter-free luminescent solar concentrators applied as windows.
关键词： Combinatorial Science,SiAlON,Sputter Deposition,Solar-Conversion
更新于2025-11-14 15:30:11
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22.2: <i>Invited Paper:</i> Sputtered Molybdenum-Oxide for Anti-Reflection Layers in Displays: Optical Properties and Thermal Stability
摘要： Molybdenum (Mo) is commonly used for thin film transistor (TFT) metallization in displays. Apart from its outstanding electronic and adhesive properties in the metallic form, it also possesses stable oxidation states, including sub-stoichiometric oxides. Depending on the amount of oxygen, the properties can be widely tuned and oxygen-deficient MoO3-y films can be electrical conducting and optically absorbing, making them suitable candidates for integration as low-reflection coatings for on/in cell touch, black matrix on array, narrow bezel, or TFT metallization. Deposition of these oxides by fully reactive sputtering from metal targets implies several problems such as lateral inhomogeneities on large substrates (>G5) and difficult control of oxygen flow. To avoid these obstacles, DC-sputtering from ceramic Molybdenum oxide targets without the addition of oxygen gas is proposed. In our work, we show the non-reactive DC-sputtering of MoOx:TaOx in a stable and reliable process with deposition rates of up to 180 nm/min. Further on, the electrical, optical, and structural properties of the resulting films are studied. The reflectance of light from external sources and the resulting color impression of the dark layer coatings is investigated on different substrates. The color coordinates of the film can be tuned by the layer thickness, the type of covered metal layer (e.g. Cu, Al, Mo), as well as composition of the oxide. From a process stability point of view, we discuss changes during additional annealing steps, and show structural changes at elevated temperatures.
关键词： Ceramic Target,Molybdenum,Sputter Deposition,Low Reflectance,Narrow Bezel,Oxide
更新于2025-09-23 15:23:52
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[IEEE NAECON 2018 - IEEE National Aerospace and Electronics Conference - Dayton, OH, USA (2018.7.23-2018.7.26)] NAECON 2018 - IEEE National Aerospace and Electronics Conference - Ultrasensitive label-free tobramycin detection with aptamer-functionalized ZnO TFT biosensor
摘要： Aminoglycoside antibiotic such as tobramycin is critical to the treatment of Gram-negative bacterial diseases such as Cystic Fibrosis (Pseudomonas aeruginosa) and other respiratory problems routinely seen in military personnel. Bottom gate (BG) zinc oxide (ZnO) ultra-thin film transistors (TFTs) were fabricated and functionalized with thiol-anchored aptamers as sensitive tobramycin biosensors and a Lower Detection Limit (LDL) of 0.1 nM was extracted from the adsorption coverage isotherm. Sputter deposition of ZnO allows the control of film thickness, stoichiometry, defects and interface states. Intrinsically high surface morphology of ZnO allows improved aptamer functionalization and sensitivity of detection.
关键词： tobramycin,functionalization,biosensor,sputter deposition,aptamer,cystic fibrosis,thin film transistor,ZnO
更新于2025-09-23 15:22:29
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In Situ Study of Sputtering Nanometer-Thick Gold Films onto 100 Nanometer-Thick Spiro-OMeTAD Films: Implications for Perovskite Solar Cells
摘要： The performance of many perovskite solar cells is closely related to the spiro-OMeTAD/gold interface since gold is used as top contacts, which renders the detailed understanding of the interface formation very important. In this work, sputter deposition as an industry-relevant, high-rate, large-scale and well-controllable deposition technique is used to prepare gold electrodes on top of a 100 nm thick spiro-OMeTAD film. In situ grazing incidence small angle X-ray scattering (GISAXS) is used to study the nanostructure-growth kinetics of the gold contact on top of the spiro-OMeTAD film during the sputter process. The results show that the gold grows in nanoscale clusters, which then coalesce into a complete yet still nanogranular layer forming the top contact with a thickness of 90 nm. Based on simulations of the 2D GISAXS patterns additional information about the shape of the nanosized gold cluster is gained at the different cluster growth stages. Furthermore, the diffusion of gold into the spiro-OMeTAD film occurs during the sputter process as verified with X-ray reflectivity. In a depth of 3.5 nm below the gold contact the gold doping level of the spiro-OMeTAD film is 6.3 % irrespective of the final gold contact thickness. Thus, the interface between the spiro-OMeTAD film and the Au contact is not sharp as commonly sketched as well as the contact is grainy, which will be both of importance for the performance of device such as perovskite solar cells.
关键词： gold contacts,spiro-OMeTAD film,sputter deposition,in situ GISAXS,growth kinetics
更新于2025-09-23 15:21:01
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Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings
摘要： Today’s advances in materials science and technology can lead to better buildings with improved energy efficiency and indoor conditions. Particular attention should be directed towards windows and glass facades—jointly known as “glazings”—since current practices often lead to huge energy expenditures related to excessive inflow or outflow of energy which need to be balanced by energy-intensive cooling or heating. This review article outlines recent progress in thermochromics, i.e., it deals with materials whose optical properties are strongly dependent on temperature. In particular, we discuss oxide-based thin surface coatings (thin films) and nanoparticle composites which can be deposited onto glass and are able to regulate the throughput of solar energy while the luminous (visible) properties remain more or less unaltered. Another implementation embodies lamination materials incorporating thermochromic (TC) nanoparticles. The thin films and nanocomposites are based on vanadium dioxide (VO2), which is able to change its properties within a narrow temperature range in the vicinity of room temperature and either reflects or absorbs infrared light at elevated temperatures, whereas the reflectance or absorptance is much smaller at lower temperatures. The review outlines the state of the art for these thin films and nanocomposites with particular attention to recent developments that have taken place in laboratories worldwide. Specifically, we first set the scene by discussing environmental challenges and their relationship with TC glazings. Then enters VO2 and we present its key properties in thin-film form and as nanoparticles. The next part of the article gives perspectives on the manufacturing of these films and particles. We point out that the properties of pure VO2 may not be fully adequate for buildings and we elaborate how additives, antireflection layers, nanostructuring and protective over-coatings can be employed to yield improved performance and durability that make TC glazings of considerable interest for building-related applications. Finally, we briefly describe recent developments towards TC light scattering and draw some final conclusions.
关键词： thermochromism,vanadium dioxide,thin film,energy-efficient glazing,coating,sputter deposition,nanoparticle
更新于2025-09-23 15:21:01
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Defect generation by nitrogen during pulsed sputter deposition of GaN
摘要： Pulsed sputter deposition has been demonstrated to be a viable process for the growth of high quality GaN and InGaN/GaN LEDs. It enables the fabrication of nitride LEDs with a red emission wavelength at large areas. In this study, we explore details on the epitaxial sputter deposition of GaN with a particular emphasis on ion damage. By changing the argon to nitrogen ratio, we adjust the growth mode from island to layer growth. TEM revealed speckles in the epitaxial GaN, which could be identi?ed as isolated basal stacking faults, acting as non-radiative recombination centers. Using Monte Carlo methods, we modeled the energies of backscattered and sputtered atoms in order to get information on the ion damage mechanisms. Considering the collisions on the way from the target to the substrate, we found energetic nitrogen to induce the speckles. A shielding mechanism based on metallic gallium has been identi?ed, leading to the strongly increased luminescence quality in comparison to the non-shielded material.
关键词： GaN,pulsed sputter deposition,stacking faults,luminescence,ion damage
更新于2025-09-23 15:21:01
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Crystal Growth and Structure-Property Optimization of Thermally Annealed Nanocrystalline Ga2O3 Films
摘要： The effects of thermal annealing on the crystal chemistry, crystallization process, index of refraction, mechanical properties, and electrical characteristics of nanocrystalline Ga2O3 films was evaluated. Ga2O3 thin films were sputtered onto Si(100) substrates at 500 oC utilizing a Ga2O3 ceramic target, while post-deposition thermal annealing was performed between a range of 500-900 oC. Both structural quality and packing density of the Ga2O3 films was improved by the thermal annealing as indicated by the X-ray diffraction and ellipsometry studies. The atomic force microscopy analysis indicates that the annealing temperature has a dramatic effect on surface roughness, especially when the annealing temperature exceeds 700 oC. Corroborating with structure and morphology changes, the high values of hardness and elastic modulus are noted for Ga2O3 films annealed at higher temperatures (800-900 oC). Index of refraction (n) and extinction coefficient (k) results, and their dispersion profiles indicate that the annealing temperature strongly influences the optical properties. The refractive index values vary in the range of 1.78–1.84 (632 nm) due to gradual improvement of structural quality, texturing and packing density upon thermal annealing. A correlation between annealing temperature, optical and electrical characteristics in Ga2O3 films is established.
关键词： Mechanical Properties,Sputter-deposition,Annealing,Electrical Properties,β-Ga2O3 Films,Crystal Chemistry
更新于2025-09-19 17:13:59
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Sputter deposited titanium oxide layers as efficient electron selective contacts in organic photovoltaic devices
摘要： Organic photovoltaics (OPV) has recently reached power conversion efficiencies of 17.3%, making it a green technology that not only offers short energy payback times and diverse photovoltaic integration schemes, but also can deliver competitive power outputs. OPV typically employs electron selective contact layers made from low work function n-type metal oxide semiconductors, such as titanium oxide (TiO2) or zinc oxide (ZnO), developed from a variety of deposition techniques. However, in the case of TiO2 interlayers, the appearance of unwanted s-shape characteristics has been reported extensively in the literature in the past, for a variety of different deposition method used. It has been shown that the s-shape arises from negatively charged chemisorbed oxygen, and that it can be deactivated by UV light illumination, which, however, is hardly compatible with real-life OPV application. In this work, we introduce sputtered crystalline titanium oxide layers as efficient s-shape-free electron selective extraction layers in organic solar-cell devices. We demonstrate that the onset of crystallization takes place at substrate growth temperatures of around 100°C for the TiOx thin films, and that the crystallization onset temperature correlates well with a strong increase in device performance, and the removal of any s-shape characteristics. Optical, structural, compositional and electronic energy-level characterizations of the TiOx layers are shown in the present work, and point to the formation of an oxide with a low surface-defect density, developed from the sputter-crystallization process. Importantly, well-functioning s-shape free PTB7:PC70BM devices are demonstrated for TiOx growth temperatures of 155°C.
关键词： Sputter Deposition,Metal Oxide Interlayers,S-Shape Free,Titanium Oxide,Organic photovoltaics
更新于2025-09-12 10:27:22