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Abstract: Cu2O nanocubes (edge length of 6 to 250nm) have been produced by annealing a copper grid at 300°C in air with the presence of tetraoctylammonium bromide (TOAB)-stabilized gold nanoparticles. The microstructure of the nanocubes has been investigated in details using conventional and high-resolution transmission electron microscopy (HRTEM), and chemical analysis has been performed using energy dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscopy (STEM). Based on the experimental results, a possible growth mechanism is proposed. [Copyright &y& Elsevier]

Abstract: Si nanocrystals (Si nc) were formed by the implantation of Si+ into a SiO2 film followed by high-temperature annealing. The microstructural evolution of Si nc with annealing time has been investigated by high-resolution transmission electron microscopy (HRTEM) in detail. Three evident growth phases have been observed: formation of amorphous Si-rich SiO x nodules; transformation of the amorphous nodules into Si nc and coalescence of small particles into larger ones. Based on the HRTEM results, a formation mechanism has been proposed for the Si nc embedded in SiO2. [Copyright &y& Elsevier]

In this paper, we report microstructural characterization of InAs/GaAs quantum dots grown by molecular beam epitaxy. The InAs islands were annealed in a range of temperatures under Pa flux. Prior to annealing, it is shown that the InAs islands are mainly lens-shaped, mostly vertically self-aligned and coherent to GaAs (1 0 0) substrate. Relaxation by misfit dislocations is occasionally found. Abnormal relaxation is observed in larger islands. Stacking faults in a V-shape are frequently formed in the lateral sides of these regions. No obvious change in island density and self-alignment occurred when the dots are annealed under Pa flux at 300°C. In contrast, remarkable changes took place upon annealing at 350°C. The vertically self-aligned islands disappear, and smooth interfaces were obtained. This morphological transition is argued to result from the replacement of arsenic by phosphorus in the InAs dots. The damage to the crystalinity of the abnormally relaxed regions cannot be removed by the post-growth annealing. The remarkable morphological transition by post-growth annealing under dissimilar anion atmosphere offers another possibility for tuning the dot morphology and hence their electronic properties. [Copyright &y& Elsevier]

Well-aligned amorphous boron nanowires are prepared using magnetron sputtering. One type is straight without any branch and the other type is feather-like in morphology. Electron energy-loss spectroscopy has been used to detect the existence of oxygen in these boron nanowires. A Gatan imaging filter system, which is attached to a Philips CM200-field emission gun transmission electron microscope, has been used to acquire elemental mapping of boron and oxygen using inner-shell ionization edges. It is revealed that both the straight and feather-like boron nanowires possess the microstructure of the outer oxidized cover layer and inner pure boron. The thickness of the outer oxidized cover layer is about 1–2 nm. It can provide useful information for the growth mechanism of boron nanowires. [Copyright &y& Elsevier]

A thermodynamic approach is presented to assess the extent of anion exchange reactions during the heteroepitaxy (molecular beam epitaxy) of dissimilar anion III–V compound semiconductor structures. It is shown that the extent of anion exchange can be predicted by the change in the Gibbs free energy. Bond strength changes can only be used as a guide in comparing the relative tendency for exchange, rather than as a criterion. The driving force for anion exchange strongly depends on the conditions during interface formation. A number of important factors, including bond strength, misfit strain energy, surface structure and energy, the equilibrium between dimers V2 and tetramers V4, and segregation are discussed in terms of their contributions to the thermodynamics. [Copyright &y& Elsevier]

Abstract: The successful molecular beam epitaxial growth of single crystalline Sc x Er1− x Sb compounds on InAs(100) substrates has been demonstrated. Ex situ high-resolution X-ray diffraction and Rutherford backscattering spectrometry with ion channeling studies indicate high crystalline quality. The surface reconstruction was monitored in situ by reflection high-energy electron diffraction (RHEED) during the growth and low-energy electron diffraction post growth. The Sc x Er1− x Sb(100) surface exhibited a mixed (1×4)/(4×1) reconstruction. The RHEED patterns and the RHEED intensity oscillations during the growth are consistent with an embedded growth mechanism for the initial Sc x Er1− x Sb growth on InAs. [Copyright &y& Elsevier]

The growth interruption (GI) effect on GaSb quantum dot formation grown on GaAs by molecular beam epitaxy was investigated. The structure characterization was performed by reflection high-energy electron diffraction (RHEED), along with photoluminescence measurements. It is found that the GI can significantly change the surface morphology of GaSb QDs. During the GI, the QDs structures can be smoothed out and turned into a 2D-like structure. The time duration of the GI required for the 3D/2D transition depends on the growth time of the GaSb layer. It increases with the increase of the growth time. Our results are explained by a combined effect of the stress relaxation process and surface exchange reactions during the GI. [Copyright &y& Elsevier]

Abstract: Bi0.4Ca0.6MnO3 (BCMO) film was epitaxially grown on a (110) SrTiO3 substrate using the pulsed laser ablation technique. The morphologies of the epitaxial films with different thicknesses were considerably different. For the Bi0.4Ca0.6MnO3 epitaxial film with a thickness of 10nm, the morphology was more like islands. As the film thickness increased to 40nm, the island became smaller, and disappeared when the film thickness reached 110nm. The growth mechanism of the epitaxial films depends on film thickness, which has been discussed. The results will shed light on the formation mechanism of BCMO epitaxial films. [Copyright &y& Elsevier]

Abstract: Copper nitride (Cu3N) is a thermally unstable material; therefore both the deposition of a stoichiometric sample and the reliable characterization of its properties constitute a big challenge. We reported here the growth of stoichiometric Cu3N films on Si (100) wafer by reactive magnetron sputtering of Cu target using pure nitrogen as working gas. At a low substrate temperature (60°C), a combination of high working pressure (>0.7Pa) and low RF power supply (<150W) favors the formation of stoichiometric deposits. With the pressure at 0.9Pa and the RF power below 100W, the deposits are [001]-oriented and consist of cubic Cu3N grains, which are typically 40nm in dimension. The lattice constant is 0.383nm as determined by both X-ray diffraction and transmission electron microscopy; and the electrical resistivity measurement reveals a typical deficit semiconductor behavior in the cubic Cu3N. The thermal decomposition temperature, being reported within 100–470°C, was determined to be ∼350°C as indicated by the presence of Cu (111) and (002) reflections after prolonged annealing. [Copyright &y& Elsevier]

Abstract: Nanocrystalline thin films of copper nitride were grown on Si (100) wafers at a low substrate temperature by reactive magnetron sputtering of Cu target with the mixture of nitrogen and argon. The influence of nitrogen deficiency upon the structural, optical and electrical properties of as-deposited films was investigated. X-ray diffraction confirms the presence of cubic Cu3N and Cu biphases irrespective of carefully optimized processing parameters. With a Cu content approaching the stoichiometry for Cu3N, the films assume a smooth morphology with densely-packed nanocrystallites of about 40–60nm in size. Those deposits containing more than 79% Cu are metallic conductors with excellent electrical conductivity via a percolation mechanism, whereas the slightly substoichiometric Cu3N films show a typical behavior of deficit semiconductor, with an optical gap of about 1.85eV as revealed by photoreflectance measurement. All the observations are discussed in terms of nitrogen reemission from the growing film. [Copyright &y& Elsevier]

We report the transmission electron microscopy (TEM) study of the microstructure of wurtzitic GaN films grown on Si(1 1 1) substrates with AlN buffer layers by metalorganic chemical vapor deposition (MOCVD) method. An amorphous layer was formed at the interface between Si and AlN when thick GaN film was grown. We propose the amorphous layer was induced by the large stress at the interface when thick GaN was grown. The In0.1Ga0.9N/GaN multiple quantum well (MQW) reduced the dislocation density by obstructing the mixed and screw dislocations from passing through the MQW. But no evident reduction of the edge dislocations by the MQW was observed. It was found that dislocations located at the boundaries of grains slightly in-plane misoriented have screw component. Inversion domain is also observed. [Copyright &y& Elsevier]

Zn1−xMnxSe thin films with different Mn compositions are grown by metal-organic chemical vapor deposition on GaAs substrate. Good crystallinity of sample is evidenced by X-ray diffraction and rocking-curve measurements. Photoluminescence (PL) properties were carefully studied. A dominant PL peak close to the band edge is observed at low temperature for samples with higher Mn concentration. The temperature-dependent PL and time-resolved photoluminescence show that this emission peak is associated with the recombination of exciton bound to Mn-induced impurity bound states. It is found that rapid thermal annealing can induce reorganization of Mn composition in alloys and significantly reduce the density of impurity induced by Mn incorporation and improve the intrinsic interband transition. [Copyright &y& Elsevier]

Polycrystalline Si nanowires (poly SiNWS) were successfully synthesized by plasma-enhanced chemical vapor deposition (PECVD) at 440°C using silane as the Si source and Au as the catalyst. The diameters of Si nanowires range from 15 to 100 nm. The growth process indicates that to fabricate SiNWS by PECVD, pre-annealing at high temperature is necessary. A few interesting nanowires with Au nanoclusters uniformly distributed in the body of the wire were also produced by this technique. [Copyright &y& Elsevier]