[en] Different doses of Al atoms were implanted into SiGe-rich SiO₂ thin films, and the impacts of the doping dose and the annealing temperature on the photoluminescence (PL) from these thin films were investigated. Al-doping promoted the nucleation of SiGe nanoparticles (NPs). The addition of Al enhanced the PL intensity owing to an increase in the number of nucleation sites. However, the Al impurity generated a deep recombination level in the band gap of the SiGe NPs. When the Al-doping dose was 6 x 10¹⁴ cm^-2, the intensity of the PL reached a maximum.

[en] Metal vapor vacuum arc ion deposition system was adapted to prepare self-supporting Ni films on substrates of betaine-sucrose/Si, potassium oleate/Si, potassium oleate-sucrose/Si, self-supporting collodion film, polished NaCl and self-supporting SiN film, respectively. Field emission scanning electron microscopy (FESEM) and atomic force microscope (AFM) were employed to analyze the surface morphology and roughness of the films and substrates. The result indicates that the mean roughness of the self-supporting Ni film depends on its depositing substrate. Glancing angle deposition can reduce the surface roughness of film. Self-supporting Ni film with the 1.5 nm mean surface roughness was obtained on self-supporting collodion film with 60 degree glancing angle. (authors)

[en] Highlights: • High density copper nanowires were deposited into TNTAs by a novel electrochemical based method. • The novel core-shell Cu NWs-TNTAs composite film shows both analogue and digital resistive switching properties. • The digital resistive switching ratio is more than 40 after 1000 I–V sweeps and remains more than 20 after 10000 cycles. -- Abstract: Electrochemical nanomaterial-based resistive switching devices (memristors) have recently attracted significant research interest because of their low cost and potential applications in nonvolatile data storage and artificial neural networks. In this paper, we report an electrochemical method to produce a novel memristor based on copper nanowire-titanium dioxide nanotube arrays (TNTAs), a core-shell composite material. TNTAs are fabricated using a cheap and effective electrochemical anodization method, and high-density copper nanowires are synthesized via excess-electrodeposition with a novel peeling-off strategy. This novel memristor shows both analogue and digital resistive switching properties by controlling the electroforming process. The R_off/R_on ratio of the digital memristor remains greater than 40 during 1000 consecutive I–V sweeps. The device shows good endurance over 10⁴ pulse cycles, with an R_off/R_on ratio greater than 20. Furthermore, the data retention time can be maintained at least for 10⁴ s. The outstanding digital resistive switching performance can be attributed to the numerous parallel copper nanowire nanoelectrodes inside the film.

[en] An array of silicon carbide nanowire (SiCNW)-carbon nanotube (CNT) heterojunctions was fabricated by high-flux Si ion implantation into a multi-walled carbon nanotube (MWCNT) array with a metal vapor vacuum arc (MEVVA) ion source. Under Si irradiation, the top part of a CNT array was gradually transformed into an amorphous nanowire array with increasing Si dose while the bottom part still remained a CNT structure. X-ray photoelectron spectroscopy (XPS) analysis shows that the SiC compound was produced in the nanowire part even at the lower Si dose of 5 x 10¹⁶ ions cm^-2, and the SiC amount increased with increasing the Si dose. Therefore, the fabrication of a SiCNW-CNT heterojunction array with the MEVVA technique has been successfully demonstrated. The corresponding formation mechanism of SiCNWs was proposed

[en] Field emission characteristics of carbon nanotube arrays synthesized by thermal chemical vapor deposition on iron ion pre-bombarded silicon substrate are enhanced by titanium ion irradiation. A pronounced degradation of turn-on electric field of 0.305 V/μm and threshold field, of which the lowest value is only 1.054 V/μm, about 0.482 V/μm at the dose of 5 x 10¹⁶ ions/cm² is as an expression of this enhancement. Scanning electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Photoelectron spectrometer and transmission electron microscopy are measured for comparison before and after the Ti ion irradiation of the carbon nanotube arrays, and the results reveal that the formation of carbon nanorod/nanotube heterostructure during ion irradiation plays a dominative role in the promotion of the field emission properties. However, high-dose irradiating transaction on carbon nanotube arrays will exert repulsive effects on the field emission characteristics for the introduction of severe structural damage. Additionally, the longtime eminent stability behaviors under high applied fields have provided a possibility for the potential application of field emission flat panel display or electron emitters based on carbon nanotube arrays.

[en] We report here a systematic study of the field emission (FE) properties of highly ordered carbon nanotube (CNT) arrays at different temperatures. The FE characteristics of the CNT arrays are significantly improved with temperature increasing from 298 K to 473 K, as evidenced by the decreases of turn-on electric field at 10 μA/cm² from 1.064 to 0.774 V/μm and threshold field at 10 mA/cm² from 1.628 to 1.418 V/μm, respectively. Moreover, the stability behavior of the CNT arrays is ameliorated at or after suffering to temperatures. Raman, EDS, XPS, and photoelectron spectrometer were employed to characterize the CNT arrays before and after the FE-Temperature measurements for comparison. Our results demonstrate that the oxygen desorption induced work function decrease (from 4.89 to 4.68 eV) of the CNT arrays after longtime exposure to temperature is responsible for the improved FE behavior, while the annealing of defects on CNTs is the main reason for the improved FE stability, which provides an effective approach to stabilizing emitters by temperature processing.

[en] We investigate the thermal conductivities of silicon nanowires (SiNWs) and their arrays based on molecular dynamics simulations. It is found that diminishing diameter, roughing surface and doping impurity of SiNWs can reduce their thermal conductivities by two or three orders of magnitude compared with that of bulk silicon crystals due to the strong phonon boundary and phonon impurity scattering. The simulated thermal conductivities of SiNW arrays demonstrate that arraying nanowires can further lower the thermal conductivity owing to the laterally-coupled effect, and the thermal conductivity of arrays decreases notably with the increased nanowire volume fraction, resulting in an ultralow thermal conductivity for the doped SiNW arrays with rough surfaces, which provides theoretical guidance of thermal management for semiconductor nanowire based microelectronic and thermoelectric devices. (paper)

[en] Photonic structures can exhibit significant absorption enhancement when an object's length scale is comparable to or smaller than the wavelength of light. This property has enabled photonic structures to be an integral component in many applications such as solar cells, light emitting diodes, and photothermal therapy. To characterize this enhancement at the single particulate level, conventional methods have consisted of indirect or qualitative approaches which are often limited to certain sample types. To overcome these limitations, we used a bilayer cantilever to directly and quantitatively measure the spectral absorption efficiency of a single silicon microwire in the visible wavelength range. We demonstrate an absorption enhancement on a per unit volume basis compared to a thin film, which shows good agreement with Mie theory calculations. This approach offers a quantitative approach for broadband absorption measurements on a wide range of photonic structures of different geometric and material compositions

[en] Highly ordered Ag nanorod arrays were successfully fabricated using a simple chemical deposition method with the assistance of porous alumina membrane (PAM) template. The products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Ag⁺ ions in the PAM nanochannels were reduced by acetaldehyde reagent and resulting in the formation of rod array structures. It is found that the diameter of the Ag nanorods is determined by the PAM template, and the length of the Ag nanorods is depended on the reaction temperature. The growth mechanism of the Ag nanorod arrays is investigated in the study.

[en] TiN/TiAlN multilayered coatings with bilayer periods (λ_BD) ranging from 6 to 30 nm were prepared on TC4 alloy and Si (100) wafer substrates by magnetic filtered pulsed vacuum cathodic arc plasma technique. The analyses with scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray energy dispersive spectroscope (EDS) and X-ray photoelectron spectroscope (XPS) with Ar + sputtering indicated that the as-deposited coatings had nanometer modulated structure, TiN and TiAlN with (111) preferred orientation were the main compounds and the average atoms ratio of N:(Ti + Al) was about 1.24–1.29. Scratch test showed that the coatings were fairly adherent to TC4 substrates, and the maximal critical load was about 57 N. The highest nano-hardness and modulus about 28 GPa and 283 GPa, respectively, were obtained for the multilayer with λ_BD = 12 nm, examined with nano-indentation method. The electrochemical corrosion test showed that the coatings improved the TC4 alloy's property of anti-corrosion effectively, especially with λ_BD = 20 nm.