Fabrication of highly-ordered nanopatterned copper nanowire arrays by photolithography

Two different patterns, one being circular and the other being QDU, of copper (Cu) nanowire arrays were successfully produced by electrochemical deposition and photolithography. The highly-ordered patterns of Cu nanowire arrays were observed to stand freely on the substrate using scanning electron microscopy (SEM). Chemical analyses have been performed on Cu nanowires using energy dispersive X-ray spectroscopy (EDS). The results confirmed that it is mainly composed of Cu. Selected-area electron diffraction (SAED) pattern indicated the nanowires are single crystalline and the growth direction of the nanowires is along the [220] direction. With the deposition time increasing, the length of Cu nanowires increaseed.     

Anisotropic interface induced formation of Sb nanowires on GaSb(111)A substrates

The growth of Sb nanowires on GaSb(111)A substrates is studied by in?situ azimuthal scan reflection high-energy electron diffraction (ARHEED). Bulk and layer contributions can be distinguished in the ARHEED transmission pattern through the Sb nanowires. The three-dimensional structure of the growing Sb nanowires is identified by post-growth atomic force microscopy (AFM) and x-ray diffraction (XRD). The lattice match of the Sb crystal along the [Formula: see text] and the GaSb crystal along [Formula: see text] directions lead to a preferential orientation of the Sb nanowires. The Sb adsorption and desorption kinetics is studied by thermal desorption spectroscopy.     

Manipulation of crystalline orientation and optical absorption of Cu nanowire arrays embedded in anodic aluminum oxide templates

Cu nanowires (NWs) with controlled crystalline orientation were obtained via electrodeposition inside the nanochannels of anodic aluminum oxide templates. By adjusting electrolyte composition, the orientation of Cu NWs was manipulated between [100] and [110]. [100]- and [110]-oriented single-crystal Cu NWs were also achieved under lower electrodeposition voltages in sulfate electrolyte and citrite electrolyte, respectively. Optical absorption spectrum measurements reveal that the surface plasma resonance peak of the Cu NW arrays has an obvious blue-shift of 11 nm when the orientation of Cu NWs is turned from [100] to [110].     

Synthesis and morphological studies of ZnCuTe ternary nanowires via template-assisted electrodeposition technique

ZnCuTe nanowires have been successfully synthesized via template-assisted one step electrodeposition technique from an aqueous solution of zinc sulphate (ZnSO₄·7H₂O), copper sulphate (CuSO₄·5H₂O) and tellurium oxide (TeO₂) at room temperature (303?K). Nanowires of diameter 200, 100 and 50?nm have been synthesized on copper and indium tin oxide coated glass substrates using track-etch polycarbonate membranes (Whatman). The morphologies and structures of electrodeposited ZnCuTe nanowires were characterized by Scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM confirmed the formation of nanowires and reveal that the morphologies of nanowires have diameter equal to the diameter of the templates used. The XRD pattern have shown a preferential growth of ZnCuTe nanowires along the (119) direction and the structure corresponding to hexagonal structure. Energy dispersive X-ray analysis confirmed that the zinc copper telluride nanowires are constituted of elements Zn, Cu and Te.     

Growth modes of epitaxial copper films on c-sapphire

Usually copper grows on c-sapphire with orientation Cu(111)Al₂O₃(0001) with Cu[2 ] along Al₂O₃[2 0]. In the present work an additional orientation is described. To understand this orientation, a microscopic model of roughness of the substrate crystal is proposed and verified.     

Enhanced field emission from copper nanowires synthesized using ion track-etch membranes as scaffolds

Copper nanowires have been synthesized at different pH values through the template assisted electrodeposition technique using polycarbonate track-etch membranes as scaffolds. The effect of pH (0.8–2.8) of the electrolyte on structure, morphology, composition and deposition rate of copper into the pores of the template, while keeping other electrochemical conditions same, was investigated. X-ray diffraction analysis confirmed the face centered cubic phase of synthesized nanowires. With the change in pH, no shift in peaks was observed except the inclusion of an additional peak of copper oxide in nanowires synthesized at pH 2.8. The nanocrystallite size, strain, lattice stress and energy density were evaluated by X-ray analysis. Field emission scanning electron microscopy images revealed that nanowires obtained at pH 0.8, 1.1 and 1.4 showed incomplete deposition in the pores of the membrane whereas, the nanowires obtained at pH 1.7 were densely stacked, vertically aligned and uniform along the diameter and that obtained from pH 2.0–2.8 had overdeposition on their top. An increase in deposition rate was observed with the increase in pH value. The average diameter of Cu nanowires was found to be ~?105 nm. The electrical conductivity of as-grown nanowires was observed to decrease 13-fold as the transition from bulk values to the nanosystem. Nanowires prepared at pH of 1.7 were characterized for their field-emission properties. A very large field-enhancement factor of ~?10,855 was obtained indicating that Cu nanowires grown by reported technique shows outstanding potential as efficient field-emitters for flat panel displays.     

Epitaxy of copper on muscovite mica

The vapour deposition of copper onto air-cleaved mica (001) has been studied by reflection high energy electron diffraction in ultrahigh vacuum. At room temperature, crystallites with random orientation and crystallites with Cu(111)mica (001) and Cu[1$\text{1}$0]mica [100] (orientation I) or Cu[1$\text{1}$0]mica [010] (orientation II) are observed. On annealing, either orientation I or orientation II dominates. Also at room temperature, good epitaxy of copper on Cu(111) occurs. Deposition at 570 K always leads to a single-crystal film in orientation I. During early growth, however, crystallites in both orientations appears to have comparable importance, but those with orientation I grow at the expense of those with orientation II during coalescence.     

Realization of nonpolar a-plane ZnO films on r-plane sapphire substrates using a simple single-source chemical vapor deposition

Nonpolar (112?0) ZnO thin films (a-plane ZnO) have been grown on (11?02) sapphire substrates (r-plane sapphire) by a simple atmospheric pressure single-source chemical vapor deposition (SSCVD) approach. The crystallinity, surface morphology and optical property of the films were investigated using high-resolution X-ray diffraction (HRXRD), scanning electron microscope (SEM) and transmission spectrum, respectively. XRD results revealed that the ZnO films were grown on the substrates epitaxially along (112?0) orientation, and the epitaxial relationship between the ZnO films and the substrates was determined to be (112?0)ZnO∥(11?02) Al2O3, and [1?101]ZnO∥[022?1]Al₂O₃. The SEM image exhibited that the a-plane ZnO films showed a high density of well-aligned ZnO sheets with rectangular structure. The transmission spectrum showed that the ZnO films were highly transparent in the visible region.     

Orientation and temperature dependence of the tensile behavior of GaN nanowires: an atomistic study

Gallium nitride (GaN) is a high-temperature semiconductor material of considerable interest. It emits brilliant light and has been considered as a key material for the next generation of high frequency and high power transistors that are capable of operating at high temperatures. Due to its anisotropic and polar nature, GaN exhibits direction-dependent properties. Growth directions along [001], [1?10] and [110] directions have all been synthesized experimentally. In this work, molecular dynamics simulations are carried out to characterize the mechanical properties of GaN nanowires with different orientations at different temperatures. The simulation results reveal that the nanowires with different growth orientations exhibit distinct deformation behavior under tensile loading. The nanowires exhibit ductility at high deformation temperatures and brittleness at lower temperature. The brittle to ductile transition (BDT) was observed in the nanowires grown along the [001] direction. The nanowires grown along the [110] direction slip in the {010} planes, whereas the nanowires grown along the [1?10] direction fracture in a cleavage manner under tensile loading.     

Structure and orientation relationship of new precipitates in a Cu–Cr–Zr alloy

The crystallography and morphology of the nano-sized precipitate particles in a ternary Cu–Cr–Zr alloy were studied by transmission electron microscopy. A new type of face-centred-cubic (f.c.c) Cr-rich precipitate was observed. This precipitate is ordered and solute enriched on alternate {110} f.c.c planes, with an ellipsoid-shaped morphology. The new orientation relationship (OR) between the precipitate and Cu matrix satisfies [211]M//[011]p and [100]M//[111]p, {-111}M//{200}p and {02-2}M//{02-2}p. The difference between this new OR and the Nishiyama–Wasserman OR between body-centred-cubic (b.c.c) Cr and the Cu matrix can be detailed by Δg vectors in the diffraction patterns. Furthermore, the precipitation strengthening effect is increased greatly with the formation of these new precipitate particles when compared to binary Cu–Cr alloys.     

Size-dependent fracture mode transition in copper nanowires

In situ uni-axial tensile tests of single-crystalline copper nanowires are performed using a micromechanical device inside a scanning electron microscope chamber. The single-crystalline copper nanowires are synthesized by solvothermal processes, and the growth direction along the wire axis is the <110> orientation as confirmed by transmission electron microscopy (TEM) selected area diffraction (SAD) analysis. The fracture strengths of copper nanowires are found to be much higher than that of bulk copper. More interestingly, both ductile and brittle-like fracture modes are found in the same batch of fabricated nanowires, and the fracture modes appear to be dependent on the diameters of tested nanowires. From the analysis of fracture surfaces, sample morphologies and corresponding stress-strain curves, the competition between deformation and fracture mechanisms controlled by initial defects density and by the probability of dislocation interactions is attributed to this intriguing size-dependent fracture mode transition.     

Wurtzite ZnSe nanowires: growth, photoluminescence, and single-wire Raman properties

Wurtzite ZnSe nanowires were prepared on GaAs substrates in a metal-organic chemical vapour deposition system. Electron microscopy shows that they are smooth and uniform in size. Both transmission electron microscopy and x-ray diffraction reveal the wurtzite structure of the nanowires, which grows along the [Formula: see text] direction. Raman scattering studies on individual nanowires were performed in the back-scattering geometry at room temperature. Besides the commonly observed longitudinal and transverse optical phonon modes, a possible surface mode located at 233?cm(-1) is also observed in the Raman spectrum. A peak located at 2.841?eV was clearly observed in the photoluminescence spectra of the nanowires, which can be assigned to near band edge emissions of wurtzite ZnSe.     

Synthesis of Single-Crystal TiO2 Nanowire Using Titanium Monoxide Powder by Thermal Evaporation

TiO 2 nanowires were synthesized successfully in a large quantity by thermal evaporation using titanium monoxide powder as precursor. X-ray diffraction results showed that all the products were pure rutile phase of TiO 2 . According to microstructural observations, the nanowires have two typical morphologies, a long straight type and a short tortuous type. The straight nanowires were obtained at a wide temperature range of 900-1050 ℃, while the tortuous ones were formed below 900 ℃. Transmission electron microscopy characterization revealed that both the straight and the tortuous nanowires are single-crystal rutile TiO 2 . The preferential growth direction of the nanowires was determined as [110] orientation according to electron diffraction and high-resolution image analyses. The morphological change of TiO 2 nanowires was discussed by considering the different atomic diffusion rates of Ti atoms caused by the phase transformation in Ti substrate at around 900 ℃.     

Highly ordered uniform single-crystal Bi nanowires: fabrication and characterization

A mechanical pressure injection technique has been used to fabricate uniform bismuth (Bi) nanowires in the pores of an anodic aluminum oxide (AAO) template. The AAO template was prepared from general purity aluminum by a two-step anodization followed by heat treatment to achieve highly ordered nanochannels. The nanowires were then fabricated by an injection technique whereby the molten Bi was injected into the AAO template using a hydraulic pressure method. The Bi nanowires prepared by this method were found to be dense and continuous with uniform diameter throughout the length. Electron diffraction experiments using the transmission electron microscope on cross-sectional and free-standing longitudinal Bi nanowires showed that the majority of the individual nanowires were single crystalline, with preferred orientation of growth along the [011] zone axis of the pseudo-cubic structure. The work presented here provides an inexpensive and effective way of fabricating highly ordered single-crystalline Bi nanowires, with uniform size distributions.     

Microwave-hydrothermal synthesis and structural characterization of PX-phase single-crystalline PbTiO3 nanowires by electron microscopy

PX-phase PbTiO₃ (PT) nanowires were synthesized by microwave-hydrothermal process, and their microstructures were characterized by electron microscopy. The PX-phase PT nanowires exhibit acicular morphology with diameter sizes of 20-80 nm and length over 1 µm. They tend to grow into a regular structure with parallel arrangement along their long axis in the [001] direction. Selected area electron diffraction patterns demonstrate the PX-phase PT nanowires with a 3-fold modulated periodicity along the [110] direction and a 4-fold modulated periodicity in the [001] direction. These results were also confirmed by the high-resolution transmission electron microscopy images.     

铜纳米线阵列的模板组装

采用电解法溶解多孔阳极氧化铝(PAA)模板的阻挡层,用直流电沉积的方法在模板中组装了铜纳米线阵列.分别用扫描电镜和X射线衍射表征铜纳米线阵列的形貌和晶体结构,用电化学法表征了铜纳米线阵列的电催化性能.结果表明,PAA去阻挡层后,伏安图上出现一个阳极氧化峰.恒电位沉积的铜纳米线直径为22nm,沿(111)晶面择优取向.铜纳米线阵列电极能催化亚硝酸根的还原,其催化电流比本体铜电极上大2倍,峰电位正移80mV.纳米铜阵列电极可用于亚硝酸盐的电化学检测.     

Characterization and photocatalytic activities of C, N and S co-doped TiO(2) with 1D nanostructure prepared by the nano-confinement effect

A novel method was developed for preparing high specific surface area (156.2?m(2)?g(-1)) one-dimensional TiO(2) nanostructures co-doped with C, N and S by the nano-confinement effect. A nonmetal doping source (thiourea) was first intercalated into the inner space of H-titanate nanotubes prepared by the hydrothermal method, and then calcined at 450?°C for 2?h in air. The as-prepared C, N and S co-doped TiO(2) nanowires exhibited high visible light and enhanced UV-vis activities in photocatalytic degradation of toluene in the gas phase. The samples were characterized by x-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, fast Fourier transform analysis, x-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectra and photoluminescence. The?results indicated that the anatase nanowires grew along the [101] direction. Doping TiO(2) nanowires with C, N and S could not only broaden the light adsorption spectra into the visible region (400-600?nm), but also inhibit the recombination of photo-induced carriers. A?mechanism is proposed to elucidate the nano-confinement effect of H-titanate nanotubes in the formation of C, N and S co-doping. Based on this mechanism, the effect of C, N and S co-doping on the band structure of TiO(2) nanowires is also discussed.     

Preferred growth orientation of metallic fcc nanowires under direct and alternating electrodeposition conditions

Gold and copper nanowires were generated through electrochemical deposition into nanoporous polymeric templates. Depending on the growth conditions, such wires exhibited a distinct textured structure as evidenced by x-ray diffraction. The preferred growth orientation is explained by applying the broken-bond model in combination with surface-energy anisotropy and energy minimization. During the growth process, the aspect ratio of the cylindrical nanowire and thus the area of the mantle surface and its contribution to the total surface energy increase. Under direct current deposition conditions, [Formula: see text] textured metallic fcc nanowires represent the configuration of lowest surface energy at aspect ratios above?1. Under alternating current deposition conditions, {110} nanowire base surfaces vanish due to their high surface energy, leading to successive development of a [Formula: see text] texture as the configuration of lowest energy at aspect ratios above 5.     

Large-scale solution-phase growth of Cu-doped ZnO nanowire networks

Film-like networks of Cu-doped (0.8-2.5 at.%) ZnO nanowires were successfully synthesized through a facile solution process at a low temperature (<100 degrees C). The pH value of solution plays a key role in controlling the density and quality of the Cu-doped ZnO nanowires and the dopant concentration of ZnO nanowires was controlled by adjusting the Cu2+/Zn2+ concentration ratio during the synthesis. The structural study showed that the as-prepared Cu-doped ZnO nanowires with a narrow diameter range of 20-30 nm were single crystal and grew along [0001] direction. Photoluminescence and electrical conductivity measurements showed that Cu doping can lead to a redshift in bandgap energy and an increase in the resistivity of ZnO. The thermal annealing of the as-grown nanowires at a low temperature (300 degrees C) decreased the defect-related emission within the visible range and increased the electrical conductivity. The high-quality ZnO nanowire network with controlled doping will enable further application to flexible and transparent electronics.     

Statistical analysis of the breaking processes of Ni nanowires

We have performed a massive statistical analysis on the breaking behaviour of Ni nanowires using molecular dynamic simulations. Three stretching directions, five initial nanowire sizes and two temperatures have been studied. We have constructed minimum cross-section histograms and analysed for the first time the role played by monomers and dimers. The shape of such histograms and the absolute number of monomers and dimers strongly depend on the stretching direction and the initial size of the nanowire. In particular, the statistical behaviour of the breakage final stages of narrow nanowires strongly differs from the behaviour obtained for large nanowires. We have analysed the structure around monomers and dimers. Their most probable local configurations differ from those usually appearing in static electron transport calculations. Their non-local environments show disordered regions along the nanowire if the stretching direction is [100] or [110]. Additionally, we have found that, at room temperature, [100] and [110] stretching directions favour the appearance of non-crystalline staggered pentagonal structures. These pentagonal Ni nanowires are reported in this work for the first time. This set of results suggests that experimental Ni conducting histograms could show a strong dependence on the orientation and temperature.