Optimization of Ultra-High Aspect Ratio Nanostructures Fabricated Using Glancing Angle Deposition

This paper presents the optimization for obtaining ultra-high aspect ratio nanostructures by GLancing Angle Deposition (GLAD). GLAD is a bottom-up, physical deposition process for creating nanometer-level features by shadows cast by seeds on the substrate at high incident angles. Based on the seeds used, GLAD can be categorized into two types: GLAD with natural seeds and pre-defined seeds (pre-seeds). When natural seeds are used, the seeds are randomly distributed with sub-100 nm feature sizes, and the percent coverage of the substrate is determined simply by the incident angle of the vapor. When the pre-seeds are used, the features can be redistributed and regrouped to generate new periodic nanostructures. This paper discusses how to obtain ultra-high aspect ratio nanopillars from natural seeds and nanoribbons from pre-defined line seeds by GLAD. In the discussion on GLAD with natural seeds, a study on the dependence of the aspect ratio on the incident angle is provided; resolvable nanopillars are obtained with aspect ratio over 1:20, and the growth mechanism is proposed for pillars with high deposition angles. Next, line seeds used in the GLAD process for creating high aspect ratio nanoribbons are discussed. Proper design and process parameters are discussed for controlling the morphologies of the nanoribbons. The ultra-high aspect ratio nanostructures are potentially used for applications including sensing, surface property alteration, and the creation of nanoporous structures.

Progress in Optimization of Physical Vapor Deposition of Thin Films

In this chapter, the current state of the art in optimization of thin film deposition processes is discussed. Based on the reliable and credible published results, the study aims to identify the applications of various optimization techniques in the thin film deposition processes, with emphasis on physical deposition methods. These methods are chosen due to their attractive attributes over chemical deposition techniques for thin film manufacturing. The study identifies the critical parameters and factors, which are significant in designing of the optimization algorithms based on the specific deposition methods. Based on the specific optimization studies, the chapter provides general trends, optimization evaluation criteria, and input-output parameter relationships on thin film deposition. Research gaps and directions for future studies on optimization of physical vapor deposition methods for thin film manufacturing are provided.

Different Approaches in Designing Sensitive Tools Based on Nanocomposite Materials for Biological Analytes Detection

Sensitive, stable and robust electrochemical sensors have been designed through modificationof the working electrodes with different complex matrices based on carbon nanomaterials andmetallic nanoparticles. Therefore, screen-printed electrodes were modified with complex matrices ofhybrid nanomaterials using physical deposition or entrapment in polymeric film. [...]

Selection of technologies for metal film application using physical deposition techniques

Introduction. Obtaining high-quality thin metal films is important for advances in the technologies of applying antifriction and wear-resistant coatings on cutting tools or parts of friction couples. Various techniques of physical film deposition are applied using technologies of cathode (ion), magnetron and ion beam assisted sputtering. The work objective is to analyze, compare and determine the feasibility of techniques for the physical deposition of thin metal films when applying antifriction and wear-resistant coatings on cutting tools or parts of friction couples. Materials and Methods. Technologies of cathode (ionic), magnetron and ion-beam sputtering are considered. Schematic diagrams, conditions and parameters of the considered processes are presented. Results. An advanced technology for the deposition of thin films, alloying and hardening of the surfaces of metal parts is magnetron sputtering. Continuous wave (cw) magnetrons are used to apply coatings of complex composition or multilayer coatings on flat substrates. Ion beam sputtering is considered a slow sputtering of the target surface by bombardment with a high-energy ion beam and deposition on the substrate surface. Under the ion implantation, the surface of metals is doped with recoil atoms, which receive high energy from accelerated ions and move a few nanometers deeper. This enables to obtain ultra-thin doped layers. Low temperature of ion implantation, the possibility of sufficiently accurate control of the depth and the impurity distribution profile, create the prerequisites for the process automation. Wear tracks are more acidified under the same wear conditions on implanted steel compared to non-implanted steel. The nonequilibrium process under ion implantation causes the formation of such alloys in the surface layers that cannot be obtained under normal conditions due to diffusion of components or limited solubility. Ion implantation makes it possible to obtain alloys of a certain composition in the surface layer. Surface properties can be optimized without reference to the bulk properties of the material. Implantation is possible at low temperatures without a noticeable change in the size of the product.Discussion and Conclusion. Cathode (ion), magnetron and ion-beam sputtering have common advantages: due to the relatively low temperature, the substrate does not overheat; it is possible to obtain uniform coatings; the chemical composition of the deposited coatings is accurately reproduced. The rest of the advantages and disadvantages of the considered methods are individual. The results can be used to create thin films through alternating magnetron and then ionbeam deposition processes, which enables to obtain films uniformly modified in depth. This is important in the production of parts of friction couples and cutting tools to improve their quality.

Combining Fluorinated Polymers with Ag Nanoparticles as a Route to Enhance Optical Properties of Composite Materials

Polymer-based nanocomposites have recently received considerable attention due to their unique properties, which makes them feasible for applications in optics, sensors, energy, life sciences, etc. The present work focuses on the synthesis of nanocomposites consisting of a polytetrafluorethylene-like matrix in which metallic nano-silver are embedded, by using multiple magnetron plasmas. By successively exposing the substrate to separate RF magnetrons using as combination of target materials polytetrafluorethylene (PTFE) and silver, individual control of each deposition process is insured, allowing obtaining of structures in which silver nanoparticles are entrapped in-between two PTFE layers with given thicknesses. The topographical and morphological characteristics investigated by means of Scanning Electron Microscopy and Atomic Force Microscopy techniques evidenced the very presence of Ag nanoparticles with typical dimension 7 nm. The chemical composition at various depositing steps was evaluated through X-ray Photoelectron Spectroscopy. We show that the presence of the top PTFE layer prevents silver oxidation, while its thickness allows the tailoring of optical properties, as evidenced by spectroellipsometry. The appearance of chemical bonds between silver atoms and PTFE atoms at interfaces is observed, pointing out that despite of pure physical deposition processes, a chemical interaction between the polymeric matrix and metal is promoted by plasma.

Non-noble metal based broadband photothermal absorbers for cost effective interfacial solar thermal conversion

In recent years, noble metal-based solar absorbers have been extensively studied as their pronounced plasmonic resonances and high solar-to-thermal conversion efficiency. However, the high cost of noble metals is the unavoidable roadblock restricting the way towards scalability. In this work, we report a nickel-based photothermal absorbers, which is capable of realizing an average solar absorption of ∼97% in the range of 400–2500 nm originating from relatively weaker collective plasmonic resonances but more pronounced single electron excitation. Importantly, it is easily fabricated via the straightforward physical deposition and cost-effective with a raw material price of ∼0.3% gold and ∼20% of silver. We used it for interfacial solar vapor generation and realized an evaporation rate of ∼0.9 kg m−2 h−1 under one sun, almost comparable to the counterparts made from noble metals. The excellent performance combined with the cost effective and scalable fabrication process makes it be a promising candidate for mass off-grid solar desalination.

SYSTEM FOR CONTROLLING MASS BALANCE OF GASES AND REAGENTS DURING FORMATION OF ION-PLASMA COATINGS

Providing an increase in the working capacity of a metal-cutting tool, it is possible to significantly increase the productivity of mechanized labor, thereby reducing the cost of purchasing a new tool and saving on other accompanying technological components. During the operation of the cutting tool, the main load is transferred to its working part, this, as a rule, leads to partial wear or complete destruction of the planes and cutting edges. There are a number of technologies for processing working surfaces, which provides them with additional strengthening, the most effective of which is the method of applying special coatings to the surface of the cutting tool. Taking into account the specifics of the processes of formation of coatings, they can be divided into three main groups [1]. The first group includes methods in which the formation of coatings is carried out mainly due to diffusion reactions between saturating elements and structures of the instrumental material. The second group includes methods of forming coatings by a complex mechanism. The third group includes methods of forming coatings due to chemical and plasma-chemical reactions of particle flux simultaneously in volumes of space immediately adjacent to the saturable surfaces of the instrumental base. One such technology is the CIB (condensation and ion bombardment) method, which is a physical deposition of coatings. The most characteristic feature of coatings produced by this method is the absence of a transition zone between the coating and the tool material. This makes it possible to obtain a complex of properties on the working surfaces of the tool without deteriorating its original properties. The article is devoted to the issues of increasing the efficiency of ion-plasma technologies through the development and implementation of an automated system for analyzing and controlling the mass balance of reagent gases under conditions of several gases supply. Thus, the improvement of the technology of coating the working surfaces of the cutting tool, namely, the effective control of the process of applying ion-plasma coatings with the introduction of an automated system for analyzing and controlling the mass balance of reagent gases under conditions of supplying several gases is an urgent task.

Rapid preparation of a Nafion/Ag NW composite film and its humidity sensing effect

In this study, a novel electrical humidity-responsive composite film was presented based on the integration of two silver nanowire (Ag NW) layers deposited via the physical deposition process with a Nafion layer sandwiched between them.

Silver Metallization Characterization and Resistivity Performance Potential toward Chemical Sensor Application

Performance of limiting resistive and capacitive signal delays increases gradually depends on the complexity degree of multilayer metallization. Electrodes sensor for electrical applications requires low surface roughness and low resistivity metal layers. Amongst conductive metal series, silver (Ag) has the lowest resistivity. On the other hand, compared to aluminum and copper, this metal also has higher oxidation resistance. This study aims to characterize Ag thin film on the glass substrate and the resistivity performance by using a physical deposition technique for chemical sensor application. A series of Ag thin film with different thickness were prepared from thermal vacuum evaporator at 3.45 x 10-5 Pa with applied current at 28 Ampere in 21 minutes. Four-point resistivity probing instrument was used for resistivity testing of the thin films with different thickness. The prepared Ag thin film shows a low average roughness at 1.89 nm. A smooth and homogeneous of Ag thin film is an advantage to provide a sensitive surface for element recognition in the development of chemical sensor and an adsorbate can be justified whereas it schematically assembled with the arrangement onto smooth and perfectly flat thin film surface. Ag thin film has shown a crystallite size with respect to 50.84 nm. The low rough surfaces have fewer nucleation sites, therefore fewer grains (crystallites) will appear. The optimum thickness was determined at 107 nm and the resistivity of Ag thin film was an average at 1.988 x10-8 Ohm m.