Thin Film Deposition Techniques Research Articles

A mechanistic approach to determine the relationship between film structure, electronic properties, and photocatalytic activity of ALD ZnO thin films on glass gibers

Atomic layer deposition (ALD), a high-conformality thin-film deposition technique, offers the opportunity to immobilize photocatalytic materials on high surface area substrates. Textile substrates are inexpensive, easily accessible materials with a fibrous nature, making them high surface area scaffolds for photocatalytic applications. This study applied ZnO thin-film coatings to fabric structures with different numbers of ALD cycles. The effect of coating thickness on the surface and electronic properties of the films and their photocatalytic properties were investigated. SEM, XRD, PL, and UV–Vis were used to examine the surface morphology, crystal structure, defects, and optical properties of the ZnO thin films. As the film thickness increased, the crystal sizes and the number of defects in the structure increased. Contact angle and Hall Effect measurements revealed that these structural defects are present on the surface of the films. Optimum wettability, mobility, and photocatalytic efficiency values were observed in the 15-nm coated samples, resulting in the highest photocatalytic activity and a turning point.

Conformal High-Aspect-Ratio Solid Electrolyte Thin Films for Li-Ion Batteries by Atomic Layer Deposition.

Lithium phosphorus oxynitride (LiPON) is a state-of-the-art solid electrolyte material for thin-film microbatteries. These applications require conformal thin films on challenging 3D surface structures, and among the advanced thin-film deposition techniques, atomic layer deposition (ALD) is believed to stand out in terms of producing appreciably conformal thin films. Here we quantify the conformality (i.e., the evenness of deposition) of thin ALD-grown LiPON films using lateral high-aspect-ratio test structures. Two different lithium precursors, lithium tert-butoxide (LiOtBu) and lithium bis(trimethylsilyl)amide (Li-HMDS), were investigated in combination with diethyl phosphoramidate as the source of oxygen, phosphorus, and nitrogen. The results indicate that the film growth proceeded significantly deeper into the 3D cavities for the films grown from LiOtBu, while the Li-HMDS-based films grew more evenly initially, right after the cavity entrances. These observations can be explained by differences in the precursor diffusion and reactivity. The results open possibilities for the use of LiPON as a solid electrolyte in batteries with high-surface-area electrodes. This could enable faster charging and discharging as well as the use of thin-film technology in fabricating thin-film electrodes of meaningful charge capacity.

Enhancing perovskite solar cell performance: Investigating the impact of post-annealing on the optoelectrical and structural properties of RF-sputtered NiO films via SCAPS-1D device modeling

In recent years, perovskite solar cells have garnered significant interest in the field of solar cell research and development, primarily due to their notable efficiency. However, their limited lifespan and material defects, particularly in the interface layer and during deposition or fabrication processes, pose challenges to their widespread adoption. Innovative approaches to material processing and design are essential to addressing these issues. This paper introduces a novel method for the deposition of nickel oxide (NiO) thin films aimed at enhancing the performance of perovskite solar cells. Our study involved depositing NiO films on glass substrates using an optimised RF magnetron sputtering process at room temperature. These films were then annealed at temperatures ranging from 100 to 400 °C in an open-air setting. X-ray diffraction analysis showed that pure NiO thin films were formed. These films had a cubic crystalline structure and were mostly oriented along the (200) plane. Crucially, annealing at 100 °C significantly improved the crystallinity of the NiO films, reducing the average crystallite size from 21.05 to 6.10 nm, as evidenced by field emission scanning electron microscopy. For solar cells, this kind of microstructural refinement is very important because it changes the optical band gap, which ranged from 3.81 to 3.86 eV depending on the annealing temperature, and it also has a big effect on the films' electrical properties. The outstanding electrical characteristics of the NiO film annealed at 100 °C are particularly remarkable. We used these improved NiO films in perovskite solar cells that had a structure of FTO/NiO/MAPbI3/PCBM/Ag and ran SCAPS-1D simulations to see how well they worked. The simulation results are promising, indicating an enhancement in cell efficiency with the potential to surpass 22 %. This advancement highlights the critical role of advanced thin film deposition techniques in advancing photovoltaic technology and marks a substantial step towards unlocking the full potential of perovskite solar cells.

Novel fabrication of mixed wettability micromodels for pore-scale studies of fluid-rock interactions.

Wettability plays a crucial role in multiphase fluid flow in porous media, impacting various geological applications such as hydrocarbon extraction, aquifer remediation, and carbon dioxide sequestration. Microfluidic methods have attracted interest for their capacity to explore and visualize essential multiphase flow dynamics at the pore level, mimicking actual rock pore structures. However, creating micromodels with representative mixed wettability is currently a challenge. Existing technology is limited to producing micromodels with a singular wettability, either water-wet or oil-wet, leaving a gap in representing mixed-wet scenarios. In this study, we introduce a novel method to fabricate microfluidic devices with controlled spatial distribution of wettability at the micro-scale, mimicking actual configurations of mixed-wet rocks arising from varied mineralogy and pore structures. The proposed method combines the soft lithography process with thin film deposition techniques. The micromodels were designed to mimic the pore network of actual reservoir rocks, and a silicon substrate served as the foundation for the photolithography process optimization and wettability alteration methodology. Perfluorodecyltrichlorosilane coating was applied using molecular vapor deposition technology for surface wettability modification. The coated parts of the microdevice substrate altered the localized wetting state of the silicon towards hydrophobic, while the wettability remained unchanged in the non-coated areas. We utilized surface measurements, including contact angle, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy, to assess the wettability, composition, thickness, shape, roughness, and overall quality of the coating. Our fabrication process successfully produced a microfluidics device with tailored mixed-wet attributes at the micro-scale, which is, to our best knowledge, the first achievement in the field. This method enables the replication of mixed-wet characteristics commonly seen in various applications, such as carbonates and shales within underground rocks, providing a more accurate examination of fundamental multiphase fluid dynamics and rock interactions at the pore level.

Development of in-Situ Methods for Solution ALD

We have proposed and demonstrated a novel thin film deposition technique by transferring the principles of atomic layer deposition (ALD), known with gaseous precursors, towards precursors dissolved in a liquid.1,2 'Solution ALD'(sALD) shares the fundamental properties of standard ‘gas ALD’ (gALD), specially the self-limiting growth and the ability to coat conformally deep pores. It has been already shown that it is possible to transfer standard reactions from gALD to sALD such as oxides and sulfides deposition. However, sALD also offers novel opportunities such as overcoming the need for volatile and thermally robust precursors, offering the possibility to grow materials that cannot be obtained by gALD and using mild conditions which allow the growth on sensitive substrates. Recently we extended the understanding of the nucleation of selected materials grown by sALD such as CuSCN, TiO2 and SnSx. The study of the nucleation process relies on, first the identification of the absorbed chemical species at the surface by in-situ infra-red spectroscopy, second the ability to determine the type of interaction of the precursor with the surface by ex-situ solid state nuclear magnetic resonance (NMR) and third the evolution of nuclei formation with in-situ x-ray reflectometry (XRR) and atomic force microscopy. We developed the necessary instrumentation to obtain measurement compatible in liquid environment for each in-situ method. Form IR we can identify the phase preferential phase that is obtained as well as the defects formation for extremely thin films and NMR shows the chemical bonding of precursors at an early stage. Additionally, the AFM and XRR investigations are needed to follow the evolution of the nuclei size and their distribution of a surface as well as the nuclei density of each half cycle.The extension of the knowledge on the reaction mechanism in sALD process appears to be crucial to design next reactions and to understand later on the properties of the layers obtained with sALD. Wu, D. Döhler, M. Barr, E Oks,M. Wolf, L. Santinacci and J. Bachmann, Nano Lett. 2015, 15, 6379 Fichtner, Y. Wu, J. Hitzenberger, T. Drewello and J. Bachmann, ECS J. Solid State Sci. Technol. 2017,6, N171

Inherently Selective Atomic Layer Deposition for Optical and Sensor Applications: Microreactor Direct Atomic Layer Processing (μDALP™)

In parallel to additive manufacturing leading the revolution in traditional manufacturing, the same principles can revolutionize traditional thin film deposition techniques. Where lithography and vapor phase deposition techniques struggle, for example, with rapid iterations for prototyping or incompatibility with the used chemistry, additive manufacturing can shine. Indeed, several approaches are in development for 3D nanopriting1,2,3.Atomic Layer Deposition, and in more general Atomic Layer Processing, offers a unique opportunity for localized 3D processing/printing due to its two-step process. While simple in theory, due to well-developed examples of Spatial Atomic Layer Deposition (SALD), in practice miniturization of SALD requires substantial effort into the creation of suitable micro-nozzles. Uniquely, ATLANT 3D has developed proprietary Spatial ALD micronozzles, naming the process microreactor Direct Atomic Layer Processing - µDALPTM.The µDALPTM process undergoes the same cyclic ALD process but, thanks to the in-house microreactor development, is only done in a localized area. The microreactor or micronozzle confines the flows of gases used for ALD within a µm-scale area on the substrate, wherein the reactive species adsorb on the surface to deposit one monolayer of the desired material. Similarly, to spatial ALD, the creation of this monolayer then hinges on the movement of the substrate.4 Since the µDALPTM process is based on physical separation, it is theoretically compatible with any ALD process. As such, the material capabilities can match traditional ALD and exceed other special or patterning thin film techniques, such as lithography, which can be costly and time-consuming, especially for rapid prototyping required for innovation.Films deposited with ATLANT 3D technology have been shown to produce high-quality, crystalline, atomically precise thin films.1 It has been used to fabricate temperature (Fig.1) and capacitive sensors with sensitivities that meet or exceed those of devices made using conventional vapor phase deposition techniques.5 Low-cost rapid prototyping facilitated by ATLANT 3D technology of such devices enables design innovation and optimization not possible with other thin film deposition techniques.ATLANT 3D platform provides flexibility in deposition geometry (Fig.2) that enables a range of optical applications that require high-precision fabrication techniques. Optically transparent films can be used as localized thin protective layers for device encapsulation, as well as for atomic corrections of defects. Alternating deposition materials enable multilayer mirror fabrication of custom dimensions. Smooth thickness gradients can be used to manufacture ultrathin optical lenses. Overlapping depositions with discrete steps enable the manufacturing of binary lenses and phase masks. Growth rate enhancement in rastered direct processing mode using ATLANT 3D technology can produce periodic grating structures.1 Conformal coatings on complex surfaces can act as functionalization layers or seed layers for further material deposition through e.g. electrochemical processes.[1] Kundrata I. et al., ALD/ALE 2022 [Int. Conf.], 2022 [2] de la Huerta C. A. M. et al., arXiv, 2020, 0523. [3] Winkler, R. et al., J. Appl. Phys., 2019, 125, 210901[4] Paul Poodt., JVSTA., 2012, 30, 010802[5] Kundrata, I. et al., Small Methods., 2022, 6 (5), 2101546 Figure 1

Accelerating the Development of New Silicon-Based Anode Materials

In this work we have demonstrated the feasibility of using thin film systems as a steppingstone to accelerate the development of commercially relevant silicon-based anode materials for Li-ion batteries. Understanding new materials in conventional particle-based electrode systems is often complex. Lithium and electrolyte interact not only with the active material particles, but also with the different supporting components of the electrode, leaving it difficult to directly assess the electrochemical contribution of the active material. This is further complicated by the electrochemical behavior of such electrodes also being strongly dependent on processing conditions, like casting and drying procedures. Additionally, it is often also a challenge to synthesize such materials in particle form with the required chemical composition and monodispersity in the first place. Therefore, it would be highly beneficial to study and screen new anode materials without having to assume and assess these different factors. That is of particular importance during the optimization stage of the chemical composition for the active material, for which a significant number of samples is typically needed. Thus, evaluating the material in a thin film system is a simple and reproducible method of determining a material’s potential as a future anode material.Such thin films of active materials can reliably be made with a large range of thicknesses, compositions, element combinations and coatings, using multiple flexible and reproducible thin film deposition techniques available. In the present work, we have investigated silicon-based materials made by PECVD and sputtering: pure silicon and sub-stoichiometric versions of silicon nitride, silicon carbide, and silicon phosphide (SiNx, SiCx, SiPx). For evaluation of the applicability of the thin film model system, in several cases we have also compared the results to particles of the same material with similar chemical composition synthesized via a free space CVD process [1].Preliminary evaluation shows good agreement between results for thin film systems compared to what is known for particles of the same material. SiNx particles show good agreement with thin film results where a high nitrogen content decreases the capacity, while increasing the stability due to the formation of a stabilizing matrix around the active silicon [2]. Differences in the differential capacity analysis of similar materials in particle and thin film forms demonstrates the greater complexity in interpreting the data from the more intricate particle-based systems. SiCx is known to react in a similar fashion as SiNx where its coulombic efficiency and capacity decreases with increasing carbon-content, while its stability has been seen to increase due to a similar stabilizing matrix [3]. Reference s : [1] H. F. Andersen et al., ECS Trans., vol. 62, no. 1, pp. 97–105, 2014.[2] A. Ulvestad et al., ACS Nano, vol. 15, no. 10, pp. 16777–16787, 2021.[3] X. D. Huang et al., RSC Adv., vol. 8, no. 10, pp. 5189–5196, 2018.

(Digital Only Presentation) Effects of Ink Solvent on the Screen-Printing Fabrication and Morphology of LSM-YSZ Thin Films Deposited on YSZ Substrate for Solid Oxide Electrochemical Cells

Screen-printing is a cheap and easy thin film deposition technique utilized in energy devices fabrication, specifically, in solid oxide electrochemical cells (SOCs). This technique offers simple set-up, film quality control and mass production. In this study, LSM-YSZ, a promising component material for SOCs application was deposited on YSZ electrolyte via screen-printing. Specifically, the study aimed to investigate the effect of the solvent used in screen-printing on the quality of the deposited film. LSM-YSZ precursor powders synthesized via glycine-nitrate combustion process (GNP) were screen-printed on YSZ substrate using different solvents, ethanol and alpha-terpineol. The structure, morphology, and conductivity values of the GNP LSM-YSZ thin films using two solvents were compared. Results showed that both solvents produced a uniform distribution of rhombohedral LSM and cubic YSZ thin films with porous morphologies but alpha-terpineol solvent exhibited more agglomerated particles. Despite having this morphology, alpha-terpineol is still preferred than ethanol due to its reproducibility and scalability as it is less volatile than the other one. Moreover, there was no significant difference between the measured total conductivities of the half-cells using two solvents with the values of 4.63e-3 S/cm and 2.07e-3 S/cm at 700°C, and activation energies of 0.374 eV and 0.483 eV from 500°C - 700°C, for ethanol and alpha-terpineol, respectively.

Molecular Layer Deposition of Metal Phosphonates: A New Class of Hybrid Coating Layers

Atomic layer deposition (ALD) is a vapor phase thin film deposition technique where materials can be grown atom-by-atom in a layer-by-layer manner. Over the course of just few years, it has become to be one of the most sophisticated methods of producing high quality thin films with control at the sub-nanometer scale. Molecular layer deposition (MLD) is a variant of ALD where molecular fragments are intentionally built into the growing films.MLD is one of the techniques which allows to grow organic-inorganic hybrid materials with thickness control at sub-nanometer level.1 Nowadays, organic-inorganic hybrid materials have been found to attract a lot of attention because of their distinctive properties obtained by combining chemical and physical properties of organic and inorganic segments. Numerous hybrid materials have been synthesized by MLD over the time; however, commercial application of those materials are still a challenge due to their hydrolytic instability in most cases. Perhaps, the most widely used hybrid materials in our daily life is polysiloxanes, or commonly called as silicones, a silicon-based hybrid material . The hydrolytic stability of Si-C and Si-O-Si bonds is the main reason of their practical usage as hybrid materials. Similarly, organophosphorus compounds are an important class of materials because they offer several alternatives to silicon-based linking in the field of hybrid materials. Most of the hybrid films produced by MLD technique contain C, O, N, and S elements in the organic part. Hybrid materials containing P-atoms are yet to be explored by MLD.Among others, metal phosphonates, in particular, an important class of organophosphorus compound, show promising application covering from ion-exchange, proton conductors, catalysts, sensors, membranes, fire retardants etc.2,3 Examples of metal-organic compounds based on phosphonic acid derivatives can be found in literature stemming several decades back. Phosphonates are widely considered as an effective metal chelating ligand. Their dianionic tetrahedral form (RPO3 -2) enables different modes of coordination with metal which is not possible with the extensively used contemporary carboxylate (RCO2 -2) ligands. P-O-M and P-C linkages are quite stable, and therefore organophosphorous compounds with phosphonate ligands have been used to produce thermally and chemically stable hybrid materials by several other techniques.4 Here, we report the synthesis of novel aluminum phosphonate hybrid layers obtained with MLD method. Trimethyl aluminum (TMA) has been used as the metal source and two different novel phosphonate ester precursors with two different organic groups have been used to grow the aluminum phosphonate layers. The growth characteristics of the layers have been studied by in situ ellipsometry, whereas the as-grown films have been characterized with different ex situ techniques like FTIR, XPS, XRD, SEM and AFM. As-deposited metal phosphonate layers show superior thermal (>500 0C in air) and complete water stability. We believe, this kind of metal phosphonate layers may open up new opportunities in the field of organic-inorganic hybrid coatings for various applications. Meng, X. J. Mater. Chem. A 5, 18326–18378 (2017).Goura, J. & Chandrasekhar, V. Chem. Rev. 115, 6854–6965 (2015).Zhu, Y.-P., Yuan, Z.-Y. & Alshareef, H. N. ACS Materials Lett. 2, 582–594 (2020).Vioux, A., Le Bideau, J., Mutin, P. H. & Leclercq, D. New Aspects in Phosphorus Chemistry IV 145–174 (Springer Berlin Heidelberg, 2004).

Machine learning-based exploration of molecular design descriptors for area-selective atomic layer deposition (AS-ALD) precursors.

Area-selective atomic layer deposition (AS-ALD) is a thin film deposition technique developed using conventional ALD by considering the surface chemical nature of the substrate. Selecting appropriate precursors is a critical step in developing an efficient AS-ALD process with high deposition selectivity. However, the current efficiency of research on viable AS-ALD precursors is limited because of the absence of theoretical design rules for precursor chemical structures. In this study, our objective is to propose molecular design principle for precursors for AS-ALD, particularly focusing on achieving high deposition selectivity of oxides on diverse substrates. Current preliminary results suggest that ML-based prediction model may provide a fundamental molecular-level understanding of the reactivity of metal oxide precursors, that can be useful for efficient selection of suitable precursors for AS-ALD. We employ density functional theory (DFT) calculations and machine learning (ML) techniques to analyze the relationship between the structure and the surface reactivity of the precursor. Considering DFT calculation data (M06L/def2-tzvp, Gaussian 09 and Orca 4.0) and information on precursor structures, artificial neural networks (ANN, neuralnet, R) are applied to identify critical descriptors of the AS-ALD process. Furthermore, we utilize this ANN model to predict precursor reactivity according to surface terminations.

Effects of sputtering pressure and annealing temperature on the characteristics of indium selenide thin films

Indium selenide is a significant two-dimensional lamellar semiconductor with excellent physical properties whose enormous potential utilization in optoelectronic devices has been practically hindered by the lack of suitable thin film deposition techniques. Herein, γ-In2Se3 thin films were successfully fabricated from an InSe-target via magnetron sputtering combined with subsequent annealing process. The effects of sputtering pressure and annealing temperature on the characteristics of as-deposited thin films were investigated. The x-ray diffraction (XRD) patterns reveal that the pristine thin films are amorphous in nature, whereas transform into polycrystalline and are identified as γ-In2Se3 phase after annealing treatment. The growth mechanism of as-deposited layers combines a two-dimensional lateral growth and a three-dimensional island growth. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) images indicate that all the samples show uniform and compact structures with no evident holes and crevices. The UV–vis-NIR spectrophotometer was employed to measure the optical transmittance and band gap of the synthesized thin films. The results show an obvious decrease in the band gap from 2.56 eV to 1.88 eV with annealing temperature increased from 400 °C to 600 °C, respectively. In addition, the difficult reasons for preparing monophase InSe thin films by magnetron sputtering method were discussed. These intriguing findings in this study may shed light on the growth of indium selenide thin films with well-crystallized and high quality.

(Digital Only Presentation) Effects of Ink Solvent on the Screen-Printing Fabrication and Morphology of LSM-YSZ Thin Films Deposited on YSZ Substrate for Solid Oxide Electrochemical Cells

Screen-printing is a cheap and easy thin film deposition technique utilized in energy devices fabrication, specifically, in solid oxide electrochemical cells (SOCs). In this study, LSM-YSZ, a promising component material for SOCs application was deposited on YSZ electrolyte via screen-printing. Specifically, the study aimed to investigate the effect of the solvent used in screen-printing and the effect of varying ink formulation on the quality of the deposited film. LSM-YSZ precursor powders synthesized via glycine-nitrate combustion process (GNP) were screen-printed on YSZ substrate using ethanol and alpha-terpineol solvents. The structure and morphology of LSM-YSZ thin films using two solvents were compared. Results showed that both solvents produced a rhombohedral LSM and cubic YSZ thin films and the use of a-terpineol solvent with higher solid content produced a desired uniform and porous morphology with homogenous pore distribution as revealed by XRD and SEM morphological results.

Benzene vapor sensing performance of different phases of copper oxide (CuxOy) thin films

Three different phases of copper oxide can be grown by thin-film deposition techniques, which differ in the oxidation state of copper. However, few studies have focused on comparing and considering sensing performance of these phases. The current study scrutinizes the benzene vapor sensing properties of various phases of copper oxide that can be used for the development of sensing device based on CuxOy thin films. RF reactive sputtering technique was employed, and different phases of copper oxide (CuO, Cu2O, and Cu4O3) were grown by tuning the sputtering power and reactive gas. The samples with phases of CuO, Cu2O, and CuO/Cu2O showed the response to benzene at different operating temperatures while the sample with the Cu4O3 phase was not sensitive to target vapor. The results demonstrated that the device based on CuO thin film can be a promising candidate to detect benzene vapor due to its remarkable sensitivity, selectivity, and stability.

Single‐Shot Wavefront Sensing with Nonlocal Thin Film Optical Filters

AbstractConventional wavefront sensors suffer from the fundamental limitation of the space‐bandwidth product and have a trade‐off between their spatial sampling interval and dynamic range. Here, nonlocal thin film optical filters with optimized angle‐ and polarization‐dependent responses are leveraged to circumvent the fundamental limitation, and a robust single‐shot wavefront sensing system with a small spatial sampling interval of 6.9 µm and a large angular dynamic range of 15° is realized. The system only requires inserting two multilayer dielectric filters, fabricated using a mature thin film deposition technique, into a conventional 4‐f imaging apparatus. The polarization‐sensitive nonlocal filters are used to map the 2D phase gradients of the incident light field to the intensity variation of the x‐ and y‐polarized light, respectively, thus enabling single‐shot 2D wavefront reconstruction from images taken by a polarization camera. Such a system may be used for a variety of applications, including high‐resolution image aberration correction, surface metrology, and quantitative phase imaging.

Positioning System of Infrared Sensors Based on ZnO Thin Film.

Infrared sensors incorporating suspended zinc oxide (ZnO) pyroelectric films and thermally insulated silicon substrates are fabricated using conventional MEMS-based thin-film deposition, photolithography, and etching techniques. The responsivity of the pyroelectric film is improved via annealing at 500 °C for 4 h. The voltage response of the fabricated sensors is evaluated experimentally for a substrate thickness of 1 µm over a sensing range of 30 cm. The results show that the voltage signal varies as an inverse exponential function of the distance. A positioning system based on three infrared sensors is implemented in LabVIEW. It is shown that the position estimates obtained using the proposed system are in excellent agreement with the actual locations. In general, the results presented in this study provide a useful source of reference for the further development of MEMS-based pyroelectric infrared sensors.

Drop-Dry Deposition of SnO2 Using a Complexing Agent and Fabrication of Heterojunctions with Co3O4.

The drop-dry deposition (DDD) is a simple chemical technique of thin film deposition, which can be applied to metal oxides. The deposition solution is an aqueous solution including a metal salt and an alkali. However, some metal ions react spontaneously with water and precipitate. This work is the first attempt to use complexing agents in DDD to suppress the precipitation. SnO2 thin films are fabricated using DDD with Na2S2O3 as a complexing agent and via annealing in air. The results of the Auger electron spectroscopy measurement show that the O/Sn composition ratio of the annealed films approached two, indicating that the annealed films are SnO2. The photoelectrochemical measurement results show that the annealed films are n-type. Co3O4/SnO2 heterojunction is fabricated using p-type Co3O4 films which are also deposited via DDD. The heterojunction has rectification and photovoltaic properties. Thus, for the first time, a metal oxide thin film was successfully prepared via DDD using a complexing agent, and oxide thin film solar cells are successfully prepared using only DDD.

Thin film charged particle detectors

Silicon tracking detectors have grown to cover larger surface areas up to hundreds of square meters, and are even taking over other sub-detectors, such as calorimeters. However, further improvements in tracking detector performance are more likely to arise from the ability to make a low mass detector comprised of a high ratio of active sensor to inactive materials, where dead materials include electrical services, cooling, mechanical supports, etc. In addition, the cost and time to build these detectors is currently large. Therefore, advancements in the fundamental technology of tracking detectors may need to look at a more transformative approach that enables extremely large area coverage with minimal dead material and is easier and faster to build. The advancement of thin film fabrication techniques has the potential to revolutionize the next-to-next generation of particle detector experiments. Some thin film deposition techniques have already been developed and widely used in the industry to make LED screens for TVs and monitors. If large area thin film detectors on the order of several square meters can be fabricated with similar performance as current silicon technologies, they could be used in future particle physics experiments. This paper aims to review the key fundamental performance criteria of existing silicon detectors and past research to use thin films and other semi-conductor materials as particle detectors in order to explore the important considerations and challenges to pursue thin film detectors.

Preliminary environmental benchmarks for a new Photonic Meta-Concrete based on state of the art radiative cooling materials

The usage of conventional air-conditioners increased due to global warming and the urban heat-island-effect in cities. These systems are responsible for 7% of global greenhouse gas emissions and 10% of the total energy consumption. Radiative Cooling is a passive cooling strategy which tries to mitigate global warming and the urban heat-island-effect by emitting heat through the atmosphere, into outer space. These materials are already studied for several decades, but for the first time a radiative cooling material is under development based on conventional concrete. In order to evaluate the environmental performance of this newly developed material compared to existing cooling materials, environmental benchmarks need to be defined. To determine such benchmark, existing, state of the art, daytime radiative cooling materials are assessed in this paper. Information on these materials is collected through a literature review. The radiative cooling materials are modelled using the generic Ecoinvent v3.6 database and the environmental impact is assessed using the Belgian LCA method for buildings, i.e. the MMG method. This method is in line with the EN15804:A2 and covers 16 environmental impact categories, such as global warming potential, acidification, eutrophication, water scarcity and toxicity. The results show that the production process of the materials, i.e. thin film deposition techniques, are poorly represented in the Ecoinvent database. Assumptions and adaptations are made based on literature and experts’ feedback. A sensitivity analysis is carried out to gain insight in the uncertainty of the assumptions made. Based on the results, preliminary environmental benchmarks are generated and the environmental impact of the first composition of the photonic meta-concrete is assessed against these benchmarks.

Large-scale and tunable transparent displays based on silver nanoparticles metasurface

We report a transparent display based on a metasurface of silver nanoparticles (Ag NPs), consisting of a transparent substrate and a layer of Ag NPs deposited by a dielectric film. The Ag NPs metasurface is prepared by a simple and direct annealing process. It presents a deep transmission valley at the wavelength of λ = 468 nm and enables desired transparent display by projecting the monochromatic image onto the metasurface. We also demonstrate that the formed Ag NPs can be approximated as truncated nanospheres, which have obvious directional scattering properties, and can radiate most of the scattered energy into the backward hemisphere with a relatively large angular beamwidth (the full width at half maximum of the scattered intensity) of ∼90°. Therefore, the fabricated displays possess wide viewing angles and high brightness characteristics. Additionally, the transmission modes can be red-shifted to the wavelength of λ = 527 nm by controlling the thickness of the deposited dielectric film. This approach using traditional thin film deposition and moderate annealing processing techniques enables simple, low-cost, and scalable fabrication in large areas for transparent displays.

Can We Rationally Design and Operate Spatial Atomic Layer Deposition Systems for Steering the Growth Regime of Thin Films?

Fine control over the growth of materials is required to precisely tailor their properties. Spatial atomic layer deposition (SALD) is a thin-film deposition technique that has recently attracted attention because it allows producing thin films with a precise number of deposited layers, while being vacuum-free and much faster than conventional atomic layer deposition. SALD can be used to grow films in the atomic layer deposition or chemical vapor deposition regimes, depending on the extent of precursor intermixing. Precursor intermixing is strongly influenced by the SALD head design and operating conditions, both of which affect film growth in complex ways, making it difficult to predict the growth regime prior to depositions. Here, we used numerical simulation to systematically study how to rationally design and operate SALD systems for growing thin films in different growth regimes. We developed design maps and a predictive equation allowing us to predict the growth regime as a function of the design parameters and operation conditions. The predicted growth regimes match those observed in depositions performed for various conditions. The developed design maps and predictive equation empower researchers in designing, operating, and optimizing SALD systems, while offering a convenient way to screen deposition parameters, prior to experimentation.