In this work we report on structural and Raman spectroscopy measurements of pure and Sn-doped In 2 O 3 nanowires. Both samples were found to be cubic and high quality single crystals. Raman analysis was performed to obtain the phonon modes of the nanowires and to confirm the compositional and structural information given by structural characterization. Cubic-like phonon modes were detected in both samples and their distinct phase was evidenced by the presence of tin doping. As a consequence, disorder effects were detected evidenced by the break of the Raman selection rules.

Dopant atoms can be incorporated into nanowires either via the vapor-liquid-solid mechanism through the catalyst droplet or by the vapor-solid growth on the sidewalls. Si is a typical n-type dopant for GaAs, but in nanowires it often suffers from a strongly amphoteric nature in the vapor-liquid-solid process. This issue can be avoided by using Te, which is a promising but less common alternative for n-type doping of GaAs nanowires. Here, we present a detailed investigation of Te-doped self-catalyzed GaAs nanowires. We use several complementary experimental techniques, such as atom probe tomography, off-axis electron holography, micro-Raman spectroscopy, and single-nanowire transport characterization, to assess the Te concentration, the free-electron concentration, and the built-in potential in Te-doped GaAs nanowires. By combing the experimental results with a theoretical model, we show that Te atoms are mainly incorporated by the vapor-liquid-solid process through the Ga droplet, which leads to both axial and radial dopant gradients due to Te diffusion inside the nanowires and competition between axial elongation and radial growth of nanowires. Furthermore, by comparing the free-electron concentration from Raman spectroscopy and the Te-atom concentrations from atom probe tomography, we show that the activation of Te donor atoms is 100% at a doping level of 4 × 10 18 cm −3 , which is a significant result in terms of future device applications.

Influence of cross-section geometry and wire orientation on the phonon shifts in ultra-scaled Si nanowires J. Appl. Phys. 110, 094308 (2011) Study on the structural and physical properties of ZnO nanowire arrays grown via electrochemical and hydrothermal depositions J. Appl. Phys. 110, 094310 (2011) Growth of single-crystalline cobalt silicide nanowires with excellent physical properties J. Appl. Phys. 110, 074302 (2011) General hypothesis for nanowire synthesis. I. Extended principles and evidential (experimental and theoretical) demonstration J. Appl. Phys. 110, 054311 (2011) Thermoelectric properties for single crystal bismuth nanowires using a mean free path limitation model J. Appl. Phys. 110, 053702 (2011) Additional information on J. Appl. Phys. The structural and optical properties of GaAsP/GaP core-shell nanowires grown by gas source molecular beam epitaxy were investigated by transmission electron microscopy, Raman spectroscopy, photoluminescence ͑PL͒, and magneto-PL. The effects of surface depletion and compositional variations in the ternary alloy manifested as a redshift in GaAsP PL upon surface passivation, and a decrease in redshift in PL in the presence of a magnetic field due to spatial confinement of carriers.

In this study, the Ti-7.5Mo experimental alloy for biomedical applications was processed showing orthorhombic (␣) martensite phase and low elastic modulus (54 GPa). The surface treatment permitted the growth of ordered TiO 2 nanotubes via anodization process. The heat treatment during in situ Raman measurement revealed that the TiO 2 nanotubes were transformed of the amorphous state for crystalline (anatase phase) around 400 • C. Annealing of the nanotubes was evaluated by XRD, SEM and Raman spectroscopy. Results showed a high stability of the nanostructure, since only for temperatures above of 500 • C, at which the phase rutile appears, the nanostructure tends to vanish. It was observed in Raman analysis an increasing of the average size of the crystallite of the anatase phase with annealing temperature ranging from 6.5 nm up to 13 nm, besides of the precipitation of the layer rutile in the interface nanotubes-substrate. It is believed that the contact between anatase crystallites or layer rutile of the interface lead to growth of the rutile phase, causing coalescence and subsequent collapse of the tubular nanostructure. The wettability, as well as, surface energy was dependent of the crystalline structure and morphology, becoming more hydrophilic in the anatase phase when as compared with amorphous and rutile phase. The typical features of the surface together excellent bulk properties (low elastic modulus) of the Ti-7.5Mo alloy can provide a guideline for future biomedical applications.

A Raman spectroscopy study has been performed, at room temperature, on the (Bi 0.5 Na 0.5 ) 0.92 Ba 0.08-3x/2 La x TiO 3 lead-free ceramic system (with x = 0, 1, 2, and 3 at.% La). The signature of the Raman spectra showed that the structural properties were noticeably affected by the La 3+ -ions concentration, revealing the