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In this work we explore the application of deep neural networks to the optimization of atomic layer deposition processes based on thickness values obtained at different points of an ALD reactor. We introduce a dataset designed to train neural networks to predict saturation times based on the dose time and thickness values measured at different points of the reactor for a single experimental condition. We then explore different artificial neural network configurations, including depth (number of hidden layers) and size (number of neurons in each layers) to better understand the size and complexity that neural networks should have to achieve high predictive accuracy. The results obtained show that trained neural networks can accurately predict saturation times without requiring any prior information on the surface kinetics. This provides a viable approach to minimize the number of experiments required to optimize new ALD processes in a known reactor. However, the datasets and training procedure depend on the reactor geometry.

The structure, chemistry, and charge of interfaces between materials and aqueous fluids play a central role in determining properties and performance of numerous water systems. Sensors, membranes, sorbents, and heterogeneous catalysts almost uniformly rely on specific interactions between their surfaces and components dissolved or suspended in the water - and often the water molecules themselves - to detect and mitigate contaminants. Deleterious processes in these systems such as fouling, scaling (inorganic deposits), and corrosion are also governed by interfacial phenomena. Despite the importance of these interfaces, much remains to be learned about their multiscale interactions. Developing a deeper understanding of the molecular- and mesoscale phenomena at water/solid interfaces will be essential to driving innovation to address grand challenges in supplying sufficient fit-for-purpose water in the future. In this Review, we examine the current state of knowledge surrounding adsorption, reactivity, and transport in several key classes of water/solid interfaces, drawing on a synergistic combination of theory, simulation, and experiments, and provide an outlook for prioritizing strategic research directions.

The authors of this review article published in 20131 would like to correct some text and references relating to the first observations and publications on molecular layering. In Sec. II, “Early Years of Atomic Layer Processes” in the original article,1 the first two sentences of the fourth paragraph should instead say “The ALD principle, where surface reactions follow a binary sequence of self-limiting half-reactions, was reported under the name ‘molecular layering’ in the 1960s by S. I. Kol’tsov from Leningrad Technological Institute.2–6 These experiments were conducted under the scientific supervision of V. B. Aleskovskii. The ‘framework hypothesis,’ an antecedent to molecular layering, was proposed by V. B. Aleskovskii in 1952.6” In addition, again in this same section and paragraph, the last two sentences should instead say “In the 1969 article,3 the authors report that the initial reaction between TiCl4 and Si–OH tends to involve 3 Si–OH, forming one Ti–Cl, whereas after the first water step, the second TiCl4 exposure reacts with 2 Ti–OH, forming Ti–Cl2 groups. In the 1969 paper,3 a planar thin film was not produced or evaluated, although nanolayers were prepared by molecular layering at that time.6” These corrections do not affect other sections or the conclusions drawn in the article.

The authors of this review article published in 20131 would like to correct some text and references relating to the first observations and publications on molecular layering. In Sec. II, “Early Years of Atomic Layer Processes” in the original article,1 the first two sentences of the fourth paragraph should instead say “The ALD principle, where surface reactions follow a binary sequence of self-limiting half-reactions, was reported under the name ‘molecular layering’ in the 1960s by S. I. Kol’tsov from Leningrad Technological Institute.2–6 These experiments were conducted under the scientific supervision of V. B. Aleskovskii. The ‘framework hypothesis,’ an antecedent to molecular layering, was proposed by V. B. Aleskovskii in 1952.6” In addition, again in this same section and paragraph, the last two sentences should instead say “In the 1969 article,3 the authors report that the initial reaction between TiCl4 and Si–OH tends to involve 3 Si–OH, forming one Ti–Cl, whereas after the first water step, the second TiCl4 exposure reacts with 2 Ti–OH, forming Ti–Cl2 groups. In the 1969 paper,3 a planar thin film was not produced or evaluated, although nanolayers were prepared by molecular layering at that time.6” These corrections do not affect other sections or the conclusions drawn in the article.

All-solid-state Li-ion batteries afford possibilities to enhance battery safety while improving their energy and power densities. Current challenges for achieving high-performance all-solid-state batteries with long cycle life include shorting resulting predominantly from Li dendrite formation and infiltration through the solid electrolyte (SE) and increases in cell impedance induced by SE decomposition at the SE/electrode interface. In this work, we evaluate the electrochemical properties of two interlayer materials, Si and LixAl(2-x/3)O3 (LiAlO), at the Li7P3S11 (LPS)/Li interface. Compared to the Li/LPS/Li symmetric cells in absence of interlayers, the presence of Si and LiAlO both significantly enhance the cycle number and total charge passing through the interface before failures resulting from cell shorting. In both cases, the noted improvements were accompanied by cell impedances that had increased substantially. The data reveal that both interlayers prevent the direct exposure of LPS to the metallic Li and therefore eliminate the intrinsic LPS decomposition that occurs at Li surfaces before electrochemical cycling. After cycling, a reduction of LPS to Li2S occurs at the interface when a Si interlayer is present; LiAlO, which functions to drop the potential between Li and LPS, suppresses LPS decomposition processes. The relative propensities toward SE decomposition follows from the electrochemical potentials at the interface, which are dictated by the identities of the interlayer materials. This work provides new insights into the phase dynamics associated with specific choices for SE/electrode interlayer materials and the requirements they impose for realizing high efficiency, long lasting all-solid-state batteries., QC 20190125

This study reports on the secondary electron emission (SEE) performance of atomic layer deposited MgO films, with thicknesses in the range from 5 to 25 nm, for the application in the Timed Photon Counter. In this novel, photodetector MgO is utilized as a material for the fabrication of ultrathin transmission dynodes (tynodes). Two different types of PECVD silicon oxide films are applied on top of MgO, in order to protect it against etching steps in the fabrication of tynodes and also as a prevention against aging. Applicability of these two materials as capping films is evaluated in terms of achieved secondary electron yield (SEY) of MgO after their removal. Emission of secondary electrons is known to depend on numerous physical and chemical properties of the material, such as surface roughness and chemical composition. On that account, morphological and structural properties of modified MgO are determined by atomic force microscope and x-ray photoelectron spectrometer and linked to the changes in SEE behavior. The authors demonstrate that the application of a suitable capping layer followed by its removal provides an SEY of 6.6, as opposed to the value of 4.8 recorded from the as-deposited MgO film. Furthermore, in a following experiment, they showed that annealing of MgO films at high temperatures (up to 1100 °C) significantly improved the secondary electron emission, elevating the SEY to 7.2., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., EKL Processing, Electronic Components, Technology and Materials

This study reports on the secondary electron emission (SEE) performance of atomic layer deposited MgO films, with thicknesses in the range from 5 to 25 nm, for the application in the Timed Photon Counter. In this novel, photodetector MgO is utilized as a material for the fabrication of ultrathin transmission dynodes (tynodes). Two different types of PECVD silicon oxide films are applied on top of MgO, in order to protect it against etching steps in the fabrication of tynodes and also as a prevention against aging. Applicability of these two materials as capping films is evaluated in terms of achieved secondary electron yield (SEY) of MgO after their removal. Emission of secondary electrons is known to depend on numerous physical and chemical properties of the material, such as surface roughness and chemical composition. On that account, morphological and structural properties of modified MgO are determined by atomic force microscope and x-ray photoelectron spectrometer and linked to the changes in SEE behavior. The authors demonstrate that the application of a suitable capping layer followed by its removal provides an SEY of 6.6, as opposed to the value of 4.8 recorded from the as-deposited MgO film. Furthermore, in a following experiment, they showed that annealing of MgO films at high temperatures (up to 1100 °C) significantly improved the secondary electron emission, elevating the SEY to 7.2., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., EKL Processing, Electronic Components, Technology and Materials

The Large Area Picosecond PhotoDetector (LAPPD) Collaboration was formed in 2009 to develop large-area photodetectors capable of time resolutions measured in pico-seconds, with accompanying sub-millimeter spatial resolution. During the next three and one-half years the Collaboration developed the LAPPD design of 20 x 20 cm modules with gains greater than $10^7$ and non-uniformity less than $15\%$, time resolution less than 50 psec for single photons and spatial resolution of 700~microns in both lateral dimensions. We describe the R\&D performed to develop large-area micro-channel plate glass substrates, resistive and secondary-emitting coatings, large-area bialkali photocathodes, and RF-capable hermetic packaging. In addition, the Collaboration developed the necessary electronics for large systems capable of precise timing, built up from a custom low-power 15-GigaSample/sec waveform sampling 6-channel integrated circuit and supported by a two-level modular data acquisition system based on Field-Programmable Gate Arrays for local control, data-sparcification, and triggering. We discuss the formation, organization, and technical successes and short-comings of the Collaboration. The Collaboration ended in December 2012 with a transition from R\&D to commercialization.

Atomic layer deposition was used to synthesize niobium silicide (NbSi) films with a 1:1 stoichiometry, using NbF5 and Si2H6 as precursors. The growth mechanism at 200oC was examined by in-situ quartz crystal microbalance (QCM) and quadrupole mass spectrometer (QMS). This study revealed a self-limiting reaction with a growth rate of 4.5 {\AA}/cycle. NbSi was found to grow only on oxide-free films prepared using halogenated precursors. The electronic properties, growth rate, chemical composition, and structure of the films were studied over the deposition temperature range 150-400oC. For all temperatures, the films are found to be stoichiometric NbSi (1:1) with no detectable fluorine impurities, amorphous with a density of 6.65g/cm3, and metallic with a resistivity {\rho}=150 {\mu}{\Omega}.cm at 300K for films thicker than 35 nm. The growth rate was nearly constant for deposition temperatures between 150-275oC, but increases above 300oC suggesting the onset of non-self limiting growth. The electronic properties of the films were measured down to 1.2K and revealed a superconducting transition at Tc=3.1K. To our knowledge, a superconducting niobium silicide film with a 1:1 stoichiometry has never been grown before by any technique., Comment: 9 figures, ~ 10 pages. Poster Jeffrey Klug @ ALD conference 2010

Atomic layer deposition was used to synthesize niobium silicide (NbSi) films with a 1:1 stoichiometry, using NbF5 and Si2H6 as precursors. The growth mechanism at 200oC was examined by in-situ quartz crystal microbalance (QCM) and quadrupole mass spectrometer (QMS). This study revealed a self-limiting reaction with a growth rate of 4.5 {\AA}/cycle. NbSi was found to grow only on oxide-free films prepared using halogenated precursors. The electronic properties, growth rate, chemical composition, and structure of the films were studied over the deposition temperature range 150-400oC. For all temperatures, the films are found to be stoichiometric NbSi (1:1) with no detectable fluorine impurities, amorphous with a density of 6.65g/cm3, and metallic with a resistivity {\rho}=150 {\mu}{\Omega}.cm at 300K for films thicker than 35 nm. The growth rate was nearly constant for deposition temperatures between 150-275oC, but increases above 300oC suggesting the onset of non-self limiting growth. The electronic properties of the films were measured down to 1.2K and revealed a superconducting transition at Tc=3.1K. To our knowledge, a superconducting niobium silicide film with a 1:1 stoichiometry has never been grown before by any technique., Comment: 9 figures, ~ 10 pages. Poster Jeffrey Klug @ ALD conference 2010

Nanostructured metal films have been widely studied for their roles in sensing, catalysis, and energy storage. In this work, we demonstrate the synthesis of compositionally controlled and nanostructured Pt/Ir films by atomic layer deposition (ALD) into porous anodized aluminum oxide templates. Templated ALD provides advantages over alternative synthesis techniques, including improved film uniformity and conformality as well as atomic-scale control over morphology and composition. Nanostructured Pt ALD films are demonstrated with morphological control provided by the Pt precursor exposure time and the number of ALD cycles. With these approaches, Pt films with enhanced surface areas, as characterized by roughness factors as large as 310, have been reproducibility synthesized. Additionally, nanostructured PtIr alloy films of controlled composition and morphology have been demonstrated by templated ALD, with compositions varying systematically from pure Pt to pure Ir. Lastly, the application of nanostructured Pt films to electrochemical sensing applications is demonstrated by the non-enzymatic sensing of glucose., Published in Advanced Functional Materials, v20 p3099-3105, 2010. The original document contains color images.

Iridium oxide (IrOx) has been widely studied due to its applications in electrochromic devices, pH sensing, and neural stimulation. Previous work has demonstrated that both Ir and IrOx films with porous morphologies prepared by sputtering exhibit significantly enhanced charge storage capacities. However, sputtering provides only limited control over film porosity. In this work, we demonstrate an alternative scheme for synthesizing nanoporous Ir and activated IrOx films (AIROFs). This scheme utilizes atomic layer deposition to deposit a thin conformal Ir film within a nanoporous anodized aluminum oxide template. The Ir film is then activated by potential cycling in 0.1 M H2SO4 to form a nanoporous AIROF. The morphologies and electrochemical properties of the films are characterized by scanning electron microscopy and cyclic voltammetry, respectively. The resulting nanoporous AIROFs exhibit a nanoporous morphology and enhanced cathodal charge storage capacities as large as 311 mC/cm2., Published in Electrochemistry Communications, v12 n11 p1543-1546, Nov 2010; published online 31 Aug 2010. Prepared in collaboration with Argonne National Laboratory, Argonne, IL. The original document contains color images.

A new method to stabilize and functionalize surfaces for surface-enhanced Raman spectroscopy (SERS) is demonstrated. Atomic layer deposition (ALD) is used to deposit a sub-1-nm alumina layer on silver film-over-nanosphere (AgFON) substrates. The resulting overlayer maintains and stabilizes the SERS activity of the underlying silver while presenting the surface chemistry of the alumina overlayer, a commonly used polar adsorbent in chromatographic separations. The relative affinity of analytes for alumina-modified AgFON substrates can be determined by their polarity. On the basis of SERS measurements, dipicolinic acid displays the strongest binding to the ALD alumina-modified AgFON among a set of pyridine derivatives with varying polarity. This strong affinity for carboxylate groups makes the SERS substrate an ideal candidate for bacillus spores detection using the dipicolinate biomarker. The SERS signal from extracted dipicolinate was measured over the spore concentration range 10-14-10-12 M to determine the saturation binding capacity of the alumina-modified AgFON surface. The adsorption constant was determined to be Kspore = 9.0 10(13) M(-1). A 10-s data collection time is capable of achieving a limit of detection of 1.4 103 spores. The shelf life of prefabricated substrates is at least 9 months prior to use. In comparison to the bare AgFON substrates, the ALD-modified AgFON substrates demonstrate twice the sensitivity with 6 times shorter data acquisition time and 7 times longer temporal stability. ALD expands the palette of available chemical methods to functionalize SERS substrates, which will enable improved and diverse chemical control over the nature of analyte-surface binding for biomedical, homeland security, and environmental applications., Published in the Journal of the American Chemical Society, v128 p10304-10309, 2006.