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With this experimental study, ZrO2/B4C/Al2O3/SiC ceramics in different weight ratios were added to 99.5% pure aluminum and composites were produced by vacuum infiltration, which is very rare in the literature. It is aimed to investigate how different ceramics will affect the technical properties of an aluminum composite. First, scanning electron microscope images were taken to examine their microstructures, and energy-dispersive x-ray spectroscopy analyses were performed. In addition, x-ray diffraction analyses of phase structures were performed. Then, the densities of the composite structures were measured. In the last stage of the experiments, hardness measurement, bending strength, and abrasive wear amount tests were carried out to determine the mechanical properties of the composite structures. According to the data obtained, a relatively homogeneous structure was obtained up to 10% of the ceramic particles in the structure. It was observed that thermal damage did not occur in the composite structures and no significant phase changes occurred. The highest infiltration distance was obtained from B4C-reinforced samples, and the lowest infiltration distances were obtained from ZrO2-reinforced samples. Ceramic reinforcement elements have reduced the density values of composite structures. With the increase in the ratio of ceramic reinforcement particles, the hardness values of the composites increased and the flexural strength values decreased. In the abrasive wear tests, the least wear loss was obtained from SiC-reinforced samples and the highest wear loss was obtained from ZrO2-reinforced samples. When the composites were evaluated according to their microstructure and mechanical strength, the best results were obtained with SiC and then Al2O3, B4C, and ZrO2 reinforcements, respectively. It has been concluded that SiC, Al2O3, B4C, and ZrO2 reinforcement elements in Al 1050-based composites produced by vacuum infiltration have a positive effect on most of the mechanical properties and a negative effect on some of them. [ABSTRACT FROM AUTHOR]

Near-stoichiometric chromium diboride films were subject to in situ annealing inside a scanning transmission electron microscope to access the thermal behavior of the film and embedded structural planar defects. Independent of films' stoichiometry, the planar defects were unaffected by the applied heat treatments. On the contrary, the interfaces between the boron-rich tissue phase and the CrB2 phase were reshaped in the overstoichometric CrB2 film. At high temperatures, diffusion of contact metal species (platinum) from the focused ion beam sample preparation was triggered, with subsequent migration onto the sample. This resulted in the formation of metal-rich regions as directly observed and characterized at the atomic level. We determined that platinum did not react with the diboride structure but is accommodated by various defects present in the film. [ABSTRACT FROM AUTHOR]

The operando hydrogen microscope is an original apparatus that has been developed to visualize the time-dependent permeation of hydrogen through a sample. This apparatus is developed based on an ultrahigh vacuum scanning electron microscope (UHV SEM). The system consists of a lens system to focus ions produced by electron-stimulated desorption (ESD), an ion detector optimized for ESD-signal detection, and a two-dimensional measurement program synchronized with the position information of the electron beam. The developed detectors and electrostatic lenses enable highly sensitive detection of the ions. In this paper, we show the details of the instrumentation of the operando hydrogen microscope. We have succeeded in recording hydrogen and deuterium flowing from the rear of metals to the surface as a series of time-lapse images, showing the time-dependent changes in the surface distribution of hydrogen and deuterium. Deuterium permeation through the metal sample was dynamically visualized at the surface by the two-dimensional mapping of the desorbed ions induced by scanning electron beam irradiation. [ABSTRACT FROM AUTHOR]

Using a scanning electron microscope, we irradiate graphene drums with electrons at an energy of 20 keV and a dosage of about 1.58 × 1017 electrons/cm2. The drums consist of graphene exfoliated in ambient air over holes having a diameter of 4.6 μm and etched into an SiO2 substrate. After irradiation, we observe that the drum's suspended monolayer (ML) region has a ratio of the Raman D peak height, ID, to the Raman G peak height, IG, as high as 6.3. In contrast, the supported ML on the SiO2 substrate has an ID/IG ratio of 0.49. Previous studies have shown that graphene drums containing air can leak in a vacuum at a low rate. We attribute the high ID/IG ratio of the suspended ML to the air that may be in the drums. We propose that the air produces much adsorbed water on the ML, resulting in a high average defect density during irradiation. We present Raman maps of the full-width-at-half maximum, position, and height of the G, 2D, D, and D' peaks before and after irradiation and maps of ID/IG and ID/ID'. We anneal the drums at temperatures from 50 to 215 °C and find that ID/IG significantly reduces to 0.42. The annealing data are analyzed using an Arrhenius plot. We also find that ID/ID' depends on annealing temperature and has values ≥8, in the range expected for sp3 defects, for ID/IG ≤ 3.9. This irradiation method may help achieve high average defect densities in ML graphene, imparting novel and potentially valuable properties. [ABSTRACT FROM AUTHOR]

Plasma etching effects, such as microtrenching and bowing, negatively impact device performance. Modeling of these effects at nanoscale is challenging, and theoretical and experimental investigations are highly desired to gain insights into mechanisms. In this paper, we propose a new plasma etching model based on Monte Carlo simulations with a cellular method. This model considers reactions and ion-enhanced etching and consists of a novel particle reflection algorithm, which is a key factor impacting the etch profile. This model reproduces the adjustable microtrenching and bowing effects in periodic dense trenches with tens of nanometer dimensions. We conduct experiments of Si etching by Cl 2 and validate the model by comparing the simulated profile with cross-sectional scanning electron microscope images. This work enables a potential physical model driven process emulation tool toward design technology co-optimization. [ABSTRACT FROM AUTHOR]

The critical dimensions of advanced semiconductor manufacturing processes have decreased to a few tens of nanometers while the aspect ratios have increased beyond 100. The performance of plasma etch patterning processes as well as the cost and time of the development cycle are critical to the success of ramping a new technology node toward profitable high-volume manufacturing. In this paper, a computational patterning software, ProETCH®, has been developed with rigorous physics and advanced algorithms for modeling the etch patterning process, with the featured capabilities in calibrating the reaction mechanisms and optimizing the etch process. A shallow trench isolation etch process using self-aligned double patterning was investigated. A reaction mechanism of silicon etch by Ar/Cl2 plasma was developed to address the surface reactions, and a plasma hypermodel was introduced to correlate process operating conditions to plasma parameters at the wafer surface. The parameters of the reaction mechanism and the plasma hypermodel were calibrated with experimental data obtained from cross-sectional scanning electron microscope (XSEM) images. The calibrated model is used to identify the different fundamental pathways that contribute to the observed profile metrics in XSEMs. The model was then used for process development and optimization by solving the forward and inverse problems. In the forward problem, the model is used to predict the etching profile at different process conditions. Predictions for both interpolation conditions (process parameters within the range used for developing the model) and extrapolation conditions (process parameters outside of the range used for developing the model) agree well with the experimental data with the root mean square error less than 4 nm (1 nm resolution used for the mesh). In the inverse problem, the developed model is used to search for process conditions (e.g., values of bias power and pressure), which could result in desirable profiles. The solutions to the inverse problem demonstrate a degeneracy in process space of the etching process for a given target profile. [ABSTRACT FROM AUTHOR]

TiN coatings were in situ deposited on un-nitrided and nitrided M2 high speed steels by electrically enhanced cathodic arc evaporation technology. The morphology, microstructure, phase composition, as well as microhardness and nano-hardness of the samples were analyzed by scanning electron microscope, optical microscope, X-ray diffraction, Vickers hardness tester, and nano-indentation, respectively. In especially, the effect of nitriding substrate current density on the adhesion strength of in situ TiN coatings was investigated by Rockwell indentation and scratch tests. The results showed that the nitrided layer thickness increased with increasing substrate current density and "bright" nitrided layer was achieved. In the Rockwell indentation test, the radial cracks on the surface of the duplex-treated samples originated from the hard and brittle nitrided layer as compared to the nitrided substrate, which corresponded to the failure mechanism of brittle fracture. In the scratch test, the adhesion strength of coating to substrates was significantly improved by nitriding pretreatment. Furthermore, the critical load of the duplex-treated samples increased with the increase of nitriding substrate current density. In addition, tensile cracks only occurred in the case of the N120/TiN sample. [ABSTRACT FROM AUTHOR]

The tribological properties of metal-CuS/MoS2 composite coatings were improved by selecting the metal materials and optimizing the heat treatment process. The composite coatings were prepared by magnetron cosputtering of copper or aluminum metals, CuS, and MoS2. Then, the prepared Cu-CuS/MoS2 and Al-CuS/MoS2 were subjected to vacuum heat treatment at 220, 320, and 420 °C. The structure and tribological properties of the composite coatings were analyzed by scanning electron microscope, energy spectrum, x-ray diffraction, Raman spectrum, and multifunction friction tester. The results showed an island-like growth and a dense noncylindrical cross-sectional morphology of the metal-CuS/MoS2 composite coating. Metal- and CuS-doped MoS2 solid solution is a practical component in composite coatings. The wear scar of the composite coatings showed different color layers at different annealing temperatures due to composition deviation. After heat treatment at 320 °C, the friction coefficient of Cu-CuS/MoS2 coating was reduced to a minimum of 0.08. After heat treatment at 420 °C, the Al-CuS/MoS2 coating showed three different color layers of wear scar, and good tribological properties were obtained. The friction coefficient of the Al-CuS/MoS2 coating was as low as 0.06, and the adhesion of the Al-CuS/MoS2 coating was expressed in the HF1 level. The results show that the vacuum heat treatment can stimulate the action of CuS by forming a solid solution with MoS2, complementing the missing S atom during the sputtering deposition of MoS2 and improving the lubrication of the composite coating. In addition, although the action mechanisms are different, Cu and Al doping are all conducive to obtaining composite coatings with better tribological properties. [ABSTRACT FROM AUTHOR]

TiSiCN composite coatings with different N contents based on Cr buffer layer were prepared by plasma-enhanced magnetron sputtering. The surface and cross-sectional morphology, composition, and structure of the coatings were evaluated by scanning electron microscope with energy dispersive spectroscopy, atomic force microscope, x-ray photoelectron spectroscopy, x-ray diffraction, and Raman spectroscopy. The hardness, elastic modulus, and tribological performance were investigated. The results showed that with the addition of N content, the proportion of sp3-hybrized C bonds and amorphous Si3N4 in TiSiCN coatings gradually decreased, while the proportion of graphite phase and CNx gradually increased. The decrease in the sp3—C bonding ratio leads to the decrease of coating hardness, and the composite coating with N content of 7.3% has the highest hardness at 13.2 GPa. The friction experiments exhibited the self-lubrication feature of the internal graphite phase, and the strengthening of moderate amounts of the hard phase can significantly reduce the wear rate. The TiSiCN composite coating with N content of 13.2% had the lowest wear rate. [ABSTRACT FROM AUTHOR]

Good specimen quality is a key factor in achieving successful scanning transmission electron microscope analysis. Thin and damage-free specimens are prerequisites for obtaining atomic-resolution imaging. Topological insulator single crystals and thin films in the chalcogenide family such as Sb2Te3 are sensitive to electron and ion beams. It is, therefore, challenging to prepare a lamella suitable for high-resolution imaging from these topological insulator materials using standard focused ion-beam instruments. We have developed a modified method to fabricate thin focused ion-beam (FIB) lamellae with minimal ion-beam damage and artifacts. The technique described in the current study enables the reliable preparation of high-quality transmission electron microscope (TEM) specimens necessary for studying ultra-thin surface regions. We have successfully demonstrated that the careful selection of FIB milling parameters at each stage minimizes the damage layer without the need for post-treatment. [ABSTRACT FROM AUTHOR]

Thin films of silver were deposited on nonalkali glass substrates at substrate temperatures ranging from room temperature (28 °C) to 150, 200, 300, 400, and 500 °C at discharge pressures of 0.40, 1.20, and 2.00 Pa using direct current magnetron sputtering. On the basis of the measured cross-sectional and surface morphologies, crystallographic structures, and film properties, I discuss the dependence of the film structure and properties on the substrate temperature. The x-ray diffraction measurements showed that the <111> orientation was preferred for all deposition conditions. Scanning electron microscope observations revealed a microstructure of convex-shaped fine grains for a substrate at room temperature, while laterally growing, mound-shaped grains with flat-topped surfaces appeared at substrate temperatures of 400 and 500 °C. Atomic force microscopy also showed an increase in the lateral size and height of the mound-shaped structures with increasing substrate temperature. The lateral grain size evaluated from the areal particle density obtained from atomic force microscopy increased significantly with increasing substrate temperature, reaching 600–800 nm at a substrate temperature of 500 °C. The film stress also changed from compressive to tensile with increasing substrate temperature. The relative density, defined as the ratio of the deposited amount-of-substance to the physical-thickness, decreased significantly with increasing substrate temperature and, at a substrate temperature of 500 °C, was approximately 0.6 times as large as that obtained for thin films deposited at room temperature. The high surface diffusivity of the Ag adatoms induces the growth of laterally growing, mound-shaped grains. Besides, the energy accumulated in the thin films during sputter deposition induces the void formation to increase the efficiency of energy release in the form of heat. [ABSTRACT FROM AUTHOR]

This paper reports two specific aspects of Si implantation in the molecular beam epitaxy grown p-type GaSb epilayer, namely, the evolution of nanoporosity and doping characteristics. The implantation is done with 100 keV Si ions at four different fluences, i.e., 5 × 1013, 1 × 1014, 5 × 1014, and 1 × 1015 ions/cm2. A field-emission scanning electron microscope (in-plane and cross-sectional view) shows a smooth nanoporous GaSb with a pore diameter of 10–20 nm for the higher fluences. The thickness of the porous film is enhanced from 235 nm (fluence: 1 × 1014 ions/cm2) to 515 nm (fluence: 1 × 1015 ions/ cm2). Development of smooth uniform porous GaSb using Si ion implantation is discussed from the viewpoint of displacement per atom and distribution of vacancies estimated through Stopping and Range of Ions in Matter simulation tool. Hall measurement shows conversion to n-type behavior after implantation and a variation in the sheet carrier concentration from 2.22 × 1014 to 8.52 × 1014 cm−2. There is a drastic change in the mobility with the onset of void formation by implantation. [ABSTRACT FROM AUTHOR]

In this study, the nanostructured NiCoCrAlY powder feedstock was coated on the substrate via the high-velocity oxy-fuel spraying process. Freestanding nanostructured NiCoCrAlY coatings were then vacuum heat-treated at 1100 °C for 1, 2, and 5 h under a pressure of 10−3 Pa. The microstructure examinations of the nanostructured NiCoCrAlY coatings before and after vacuum heat treatment were investigated using x-ray diffraction and the field-emission scanning electron microscope equipped with electron dispersed spectroscopy analysis. In order to measure the high-temperature oxidation resistance, the freestanding coatings were evaluated using the isothermal oxidation test at 1000 and 1100 °C, respectively, under the air atmosphere. The obtained results showed that homogeneous and adherent α-Al2O3 was successfully formed on the surface of the heat-treated coating during isothermal oxidation. Results also indicated that the heat-treated NiCoCrAlY coating had a higher isothermal and cyclic oxidation resistance. As a consequence, a lower oxide growth rate was achieved by controlling diffusion due to the finer and denser structure of Al2O3 on the heat-treated nanostructured coating for 2 h after the oxidation test. [ABSTRACT FROM AUTHOR]

In this study, the authors have demonstrated that it is possible to realize several three-dimensional (3D) micro- and nanostructures, by the fabrication of the smallest microhouse using a dual beam scanning electron microscope (SEM)/focused ion beam (FIB) Auriga 60 from Zeiss together with a six degree of freedom robot built with SmarAct components. In this new type of nanolab, cutting, etching, folding, assembling, and then welding thin membranes of silica on top of a cleaved optical fiber SMF28, or production of micro- and nanostructures, like the microhouse, are possible. The authors have experimentally shown that FIB can be used, in this new generation of micro/nanofactory, in combination with SEM, and gas injection system, in order to fabricate three-dimensional microstructures: a microhouse in this study, with ultrahigh accuracy assembly down to 10 nm. By using the theory of sputtering, the authors are able to propose a model of folding thin membranes of numerous materials such as metals, polymers, or crystals, i.e., silica, silicon, potassium tantalite, or lithium niobate. This method is usually described as origami in the literature [W. J. Aroa, H. I. Smith, and G. Barbastathis, Microelectron. Eng. 84, 1454 (2007); W. J. Aroa et al., J. Vac. Sci. Technol., B 25, 2184 (2007); and K. Chalapat et al., Adv. Mater. 25, 91 (2013)]. The experimental results indicate that the introduction of a microrobot inside the SEM vacuum chamber will provide the means to enlarge the scope of clean room facilities to build complex and smart 3D microsystems with heterogeneous materials, especially on the facet of an optical fiber in the lab on fiber new field. The authors propose a new way to easily manufacture many kinds of optical functions for light trapping based on nanoantennas, nanophotonic crystal, axicon or lattice, 3D biosensor with origami, and nanopatterning surfaces or carbon nanotubes, etc. [ABSTRACT FROM AUTHOR]

With rapidly increasing numbers of studies of new and exotic material uses for perovskites and quasicrystals, these demand newer instrumentation and simulation developments to resolve the revealed complexities. One such set of observational mechanics at the nanoscale is presented here for somewhat simpler material systems. The expectation is that these approaches will assist those materials scientists and physicists needing to verify atomistic potentials appropriate to the nanomechanical understanding of increasingly complex solids. The five following segments from nine University, National and Industrial Laboratories both review and forecast where some of the important approaches will allow a confirming of how in situ mechanics and nanometric visualization might unravel complex phenomena. These address two-dimensional structures, temporal models for the nanoscale, atomistic and multiscale friction fundamentals, nanoparticle surfaces and interfaces and nanomechanical fracture measurements, all coupled to in situ observational techniques. Rapid future advances in the applicability of such materials science solutions appear guaranteed. [ABSTRACT FROM AUTHOR]

A recent short history of reactive evaporation by D. M. Mattox [History Corner--A Short History of Reactive Evaporation, SVC Bulletin (Society of Vacuum Coaters, Spring 2014), p. 50-51] describes various methods for producing oxides, nitrides, carbides, and some compounds, but hydrides were not mentioned. A study was performed in the mid-1970s at the General Electric Company Neutron Devices Department in Largo, FL, by the author to study preparation of thin film hydrides using reactive evaporation and to determine their unique characteristics and properties. Films were produced of scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), and the rare earth praseodymium (Pr), neodymium (Nd), gadolinium (Gd), dysprosium (Dy), and erbium (Er) hydrides by hot crucible filament and electron beam evaporation in atmospheres of deuterium and tritium gases. All-metal vacuum systems were used and those used with tritium were dedicated for this processing. Thin film test samples 1000 nm thick were prepared on 1.27 cm diameter molybdenum disk substrates for each occluder (i.e., an element that can react with hydrogen to form a hydride) material. Loading characteristics as determined by gas-to-metal atomic ratios, oxidation characteristics as determined by argon-sputter Auger analysis, film structure as determined by scanning electron microscope analysis, and film stress properties as determined by a double resonator technique were used to define properties of interest. Results showed hydrogen-to-metal atomic ratios varied from 1.5 to 2.0 with near maximum loading for all but Pr and Nd occluders which correlated with the oxidation levels observed, with all occluder oxidation levels being variable due to vacuum system internal processing conditions and the materials used. Surface oxide levels varied from ~80 Å to over 1000 Å. For most films studied, results showed that a maximum loading ratio of near 2.0 and a minimum surface oxide level of ~80 Å could be obtained with a bulk film oxygen level of ~0.54 oxygen as determined by microprobe analysis when an evaporation rate of ~0.313 mg/cm2 min was used in an atmosphere of D2 or T2 gas at a system deposition pressure of 1 × 10-3 Torr (1.33 × 10-1 Pa) in an evaporation time of ~2 min. Platelet type (i.e., a film microstructure showing an overlay of flat plates with large grain sizes) film structures were observed for most films with some film mechanical properties determined (i.e., grain size and Vickers µ-hardness), and reduced stress levels were seen with initial normalized differential (tensile) stress levels being (1.0-4.0) × 108 dyne/cm² for tritium loaded samples and (1.5 ± 0.5) × 109 dyne/cm² for deuterium loaded samples. Also, stress aging characteristics were determined for some hydride films prepared in a radioactive tritium gas atmosphere. Tritium loading, however, had the undesirable characteristic of having to dispose of the internal processing system fixtures, which can be minimized, but the reactive evaporation technique produced desirable thin films. [ABSTRACT FROM AUTHOR]

A novel method for cleaning a high vacuum chamber is presented. This method is based on concurrent in situ high-energetic UV light activation of contaminants located in the residual gas and at the vacuum chamber surfaces as well as the in situ generation of highly reactive ozone. Ozone oxidizes the contaminants to volatile species. Investigations by energy-dispersive x-ray analysis of residual gas depositions and mass-spectroscopy measurements of the residual gas in the vacuum chamber identify the contaminant species as hydrocarbons. After a cleaning period of 8 h, a decrease in measured chamber contamination by about 90% could be achieved according to atomic force microscope analysis. Mass spectroscopy measurements using a residual gas analyzer indicate the creation of volatile, carbonaceous species during the cleaning process. [ABSTRACT FROM AUTHOR]

Film deposition of Ni2MnGa phaselike alloy by radio frequency (rf) magnetron sputtering was performed onto bare Si(100) substrates and LaNiO3/Pb(Ti,Zr)O3 (LNO/PZT) ferroelectric buffer layer near room temperature. The prepared samples were characterized using conventional x-ray diffraction (XRD), superconducting quantum interference device, and electron dispersive x-ray spectroscopy from scanning electron microscope observations. The optimized films deposited under high rf power and low argon pressure present good surface quality and highly textured phase crystallization. The positioning distance between the substrate and the target-holder axis has some limited effect on the film’s composition due to the specific diffusion behavior of each element in the sputtering plasma. Extended four pole high resolution XRD analysis allowed one to discriminate the intended Ni–Mn–Ga tetragonal martensitic phase induced by the (100) LNO/PZT oriented buffer. This low temperature process appears to be very promising, allowing separate control of the functional layer’s properties, while trying to achieve high electromagnetoelastic coupling. [ABSTRACT FROM AUTHOR]

A gas-injection system (GIS) heats up a powdery substance and transports the resulting gas through a capillary into a vacuum chamber. Such a system can be used to guide a (metal)organic precursor gas very close to the focal area of an electron or ion beam, where a permanent deposit is created and adheres to the substrate. This process is known as focused particle beam-induced deposition. The authors present design principles and give construction details of a GIS suitable for ultrahigh vacuum usage. The GIS is composed of several self-contained components which can be customized rather independently. It allows for a continuously adjustable gas-flow rate. The GIS was attached to a standard scanning electron microscope (JEOL 6100) and tested with the tungsten precursor W(CO)6. The analysis of the deposits by means of atomic force microscopy and energy dispersive x-ray spectroscopy provides clear evidence that excellent gas-flow-rate stability and ensuing growth rate and metal-content reproducibility are experienced. [ABSTRACT FROM AUTHOR]

In this study, a new method coupling laser irradiation into a dual-beam scanning electron microscope (SEM) and focused-ion-beam (FIB) system is developed. By using a lensed fiber, pulsed laser illumination could be successfully delivered onto the sample under SEM imaging, providing in situ monitoring for laser material processing applications including local modification of micro-/nanostructures and laser-assisted chemical vapor deposition. In situ characterization of the laser-induced features by high resolution SEM imaging and energy dispersive x-ray spectrometry was successfully carried out. Furthermore, in situ repair of a contaminated lensed fiber probe during laser-assisted chemical vapor deposition was demonstrated via FIB milling. The results demonstrate the full compatibility of the lensed fiber apparatus with the dual-beam apparatus without disturbing the original functions of the system. The combination of guided laser radiation with SEM and FIB instruments offers a powerful capability for in situ monitoring of multilevel laser-based micro- and nanoscale material processing. [ABSTRACT FROM AUTHOR]

In this study, a two-step growth method with a thin predeposited indium (In) layer is reported to grow high-quality indium nitride (InN) films on silicon (Si) substrates by metal-organic chemical vapor deposition. The surface morphologies of the InN films exhibited good surface quality as determined by scanning electron microscope and atomic force microscope. The wurtizite structure with lattice constants c=5.69 Å and a=3.44 Å of the InN films was observed by high-resolution transmission electron microscopy. A 540 arc sec full width at half maximum of InN(0002) diffraction peak and a 0.756 eV room-temperature interband transition energy of the InN films were also observed from x-ray diffraction and photoluminescence spectroscopy, respectively. A small temperature coefficient of ∼0.036 meV/K for the band gap of InN was determined. Such a small value could be explained by the small lattice mismatch and thermal expansion of InN on the Si substrate. [ABSTRACT FROM AUTHOR]

Gold nanotubes with SiOx nanowires as sacrificial templates have been synthesized. SiOx nanowires were functionalized by 3-aminopropyl trimethoxysilane that generates a charged surface. The attachment of negatively charged Au nanoparticles was followed. The coverage of Au nanoparticles was initially less than 30%. Further coverage was achieved by the reduction of gold hydroxide to grow the continuous nanoshell on Au nanoparticles, which serve as nucleation sites. The final coverage of Au nanoshells on SiOx nanowires depends strongly on the relative amount of SiOx nanowires in gold hydroxide solution. Both transmission electron microscope and scanning electron microscope images revealed the formation of Au nanotubes with the removal of SiOx nanowires by etching in a dilute HF solution. [ABSTRACT FROM AUTHOR]