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Highlights: [•] The hydrophilicity of quartz substrate was enhanced by femtosecond laser patterning. [•] The roughness values measured using an atomic force microscope show a five-fold enhancement in roughness value along the laser written grooves. [•] Fibroblast cells plated on the patterned surface were found to respond to the roughness variation and preferentially align along the grooves. [•] No chemical changes were observed for the substrate as well as for the aligned and un-aligned cells, as evidenced by micro-Raman spectral measurements. [Copyright &y& Elsevier]

Highlights: [•] The so-called “salt effect” is exploited to improve the vapor phase oxidation method. [•] Nitric acid vapors are generated adding 20wt% of Mg(NO3)2 to HNO3 +H2O solution. [•] This allows handling more diluted solutions and varying the HNO3 vapor concentration. [•] The CNT functionalization degree increases linearly with the HNO3 vapor concentration. [•] Selecting the proper acid vapor concentration allows obtaining the desired oxidation degree. [ABSTRACT FROM AUTHOR]

Abstract: Wurtzite zinc oxide (ZnO) nanochains have been synthesized through high-pressure pulsed laser deposition. The chain-like ZnO nanostructures were obtained from magnesium (Mg) doped ZnO targets, whereas vertically aligned nanorods were obtained from primitive ZnO targets. The Mg doping has influenced the morphological transition of ZnO nanostructures from nanorods to nanochains. The field emission scanning electron microscope images revealed the growth of beaded ZnO nanochains. The ZnO nanochains of different diameters 40 and 120nm were obtained. The corresponding micro-Raman spectra showed strong E2H mode of ZnO, which confirmed the good crystallinity of the nanochains. In addition to near band edge emission at 3.28eV, ZnO nanochains show broad deep level emission at 2.42eV than that of ZnO nanorods. [Copyright &y& Elsevier]

Abstract: The corrosion products formed on a multiphase Cu–11.40Al–0.55Be (wt.%) alloy in 3.5% NaCl at open circuit potential, and their evolution with immersion time were studied mainly by micro-Raman and in situ AFM measurements. The aluminium content of each phase affects the formation of the corrosion products on them. After 1 day of immersion, γ2 precipitates were more susceptible to dealuminization, while α′ phase exhibited a high corrosion stability. The corrosion products evolved with immersion time, and CuCl2 and a Cu2O/CuO double layer film were the stable products formed on all the phases after long times. [Copyright &y& Elsevier]

Abstract: The deformation mechanisms of GaN thin films obtained by metal-organic chemical vapor deposition (MOCVD) method were studied using nanoindentation with a Berkovich diamond indenter, micro-Raman spectroscopy and the cross-sectional transmission electron microscopy (XTEM) techniques. Due to the sharpness of the tip of Berkovich indenter, the nanoindentation-induced deformation behaviors can be investigated at relatively lower load and, hence, may cover wider range of deformation-related phenomena over the same loading range. The load–displacement curves show the multiple “pop-ins” during nanoindentation loading. No evidence of nanoindentation-induced phase transformation and cracking patterns were found up to the maximum load of 300mN, as revealed from the micro-Raman spectra and the scanning electron microscopy (SEM) observations within the mechanically deformed regions. In addition, XTEM observation performed near the cross-section of the indented area revealed that the primary deformation mechanism in GaN thin film is via propagation of dislocations on both basal and pyramidal planes. The continuous stiffness measurement (CSM) technique was used to determine the hardness and Young''s modulus of GaN thin films. In addition, analysis of the load–displacement data reveals that the values of hardness and Young''s modulus of GaN thin films are 19±1 and 286±25GPa, respectively. [Copyright &y& Elsevier]

Abstract: Pulsed UV laser drilling can be applied to fabricate vertical electrical interconnects (vias) for AlGaN/GaN high electron mobility transistor devices on single-crystalline silicon carbide (SiC) substrate. Through-wafer micro holes with a diameter of 50–100μm were formed in 400μm thick bulk 4H–SiC by a frequency-tripled solid-state laser (355nm) with a pulse width of ≤30ns and a focal spot size of ∼15μm. The impact of laser machining on the material system in the vicinity of micro holes was investigated by means of micro-Raman spectroscopy and transmission electron microscopy. After removing the loosely deposited debris by etching in buffered hydrofluoric acid, a layer of <4μm resolidified material remains at the side walls of the holes. The thickness of the resolidified layer depends on the vertical distance to the hole entry as observed by scanning electron microscopy. Micro-Raman spectra indicate a change of internal strain due to laser drilling and evidence the formation of nanocrystalline silicon (Si). Microstructure analysis of the vias’ side walls using cross sectional TEM reveals altered degree of crystallinity in SiC. Layers of heavily disturbed SiC, and nanocrystalline Si are formed by laser irradiation. The layers are separated by 50–100nm thick interface regions. No evidence of extended defects, micro cracking or crystal damage was found beneath the resolidified layer. The precision of UV laser micro ablation of SiC using nanosecond pulses is not limited by laser-induced extended crystal defects. [Copyright &y& Elsevier]

Abstract: Scanning Auger microscopy and micro-Raman spectroscopy are combined to characterize a Co–Se thin film sample, containing 84at.% Se, which had been modified in localized areas following excitation with an intense focused Ar+ laser (514.5nm). The information obtained helps to establish that a previous assignment for a Co–Se sample of Raman features between 168 and 175cm−1 actually refers to an oxygenated Co–Se species, and that Co–Se interactions in a Se-rich environment give rise to Raman structure between 181 and 184cm−1. Comparisons are made for the use of Ar+ and HeNe laser sources for Raman measurements in this context; the latter in general gives both better resolution and better signal-to-noise characteristics. [Copyright &y& Elsevier]

Abstract: GaAs nanocrystals were grown on indium tin oxide substrate by an electrodeposition technique. Atomic force microscopic measurement indicates an increase in the size of the nanocrystal with decrease in the electrolysis current density accompanied by the change in the shape of the crystallite. Transmission electron microscopic measurements identify the crystallite sizes to be in the range of 10–15nm and the crystal structure to be orthorhombic. On account of the quantum size effect, the first optical transition was blue shifted with respect to the band gap of the bulk GaAs and the excitonic peak appeared prominent. A localized phonon mode ascribed to certain point defect occurred in the room temperature micro-Raman spectrum. [Copyright &y& Elsevier]

[Display omitted] • Doping monitoring of p-type Si via Raman spectroscopy with visible and UV excitations. • First-order Raman Stokes Si peak analysis via an improved Fano-like fitting model. • Illustration of a linear doping dependence of the wavelength-independent parameters. • Analysis of the excitation energy dependence of asymmetry reciprocal parameter q−1. • Demonstration of the full portability of Raman dopant monitoring to Si nano-devices. The doping concentration of B doped single-crystal Czochralski Si(1 0 0) wafers (6 × 1014-5 × 1019 cm−3) has been monitored via micro-Raman spectroscopy using visible (633 and 532 nm) and near-UV (355 nm) laser excitations at low power (5 mW). Data have been analysed with unprecedented accuracy via a convoluted Fano-Gaussian model of the first-order Raman Stokes mode of Silicon. This allowed the determination of the fitting spectral parameters (peak position and width) with an accuracy of 0.01 cm−1, which enables a reliable probing of the concentration. We observed, independently on the excitation wavelength used, a widening (up to 6.5 cm−1), a frequency-softening (up to 1.5 cm−1) and an intensity reduction (down to 90 %) of the Si peak with the doping concentration. The widening and frequency-softening follow a strictly linear dependence with doping concentration, allowing a calibration. A linear dependence of the reciprocal Fano asymmetry parameter ( q - 1 ) with excitation energy is verified, with the slope showing a linear behavior with the doping concentration and providing a direct estimate on the hole-phonon interaction strength. Results are reproduced with surface-sensitive near-UV Raman spectroscopy on BF 2 + ion implanted and laser thermal annealed (LTA) Si, demonstrating the full portability of the Raman technique to state-of-the-art nanoelectronics. [ABSTRACT FROM AUTHOR]

• Electron writing in thin YBCO films using standard TEM equipment is possible. • Electron beam processing of epitaxial YBCO films depends on the film substrate used. • High fluency irradiation effects are stronger in YBCO on MgO than in YBCO on LSAT. • Mismatch of the YBCO structure to the substrate leads to heat confinement effects. The influence of substrate material on electron writing (EW) procedures directed at fabrication of artificial channels for easy vortex motion in YBa 2 Cu 3 O 7−δ (YBCO) epitaxial thin films has been investigated. Films deposited on two types of substrates providing epitaxial growth, magnesium oxide (MgO) and La 0.18 Sr 0.82 Al 0.59 Ta 0.41 O 3 (LSAT) substrates, have been irradiated in a standard electron transmission microscope with low and high fluency 30 keV electrons. The effects of irradiation have been assessed by the measurements of the superconducting transition temperature and the critical current, completed by the micro-Raman spectroscopy and transmission electron microscopy structural investigations. The irradiation effects were found to depend on the type of substrate on which films were deposited. Differences have been attributed to distinct structural properties of the films, resulting from different matching of substrates lattices to the YBCO crystalline lattice. A stronger mismatch of MgO substrates causes the formation of in-plane disoriented epitaxial grains and significant heat confinement during EW procedures. Heat confinement mechanism, together with differences in the thermal properties of the substrates enables understanding the performance of different YBCO films in electron writing procedures. [ABSTRACT FROM AUTHOR]

Abstract: Through-wafer vertical electrical interconnects (vias) with diameters varied from 15 to 80μm were formed on Si substrates using a UV diode-pumped solid state laser (355nm). Micro-Raman spectroscopy was employed for the investigation of stress and structural changes induced in silicon within the heat-affected zone due to laser machining. A maximum stress of ∼300MPa, as a result of laser drilling, was observed close to the via edge. It was found that the stress decays within a distance of 1–3μm from the via’s side-wall and that the laser machining did not lead to the formation of amorphous silicon around the via structures. [Copyright &y& Elsevier]

• Bimetallic nanoparticles (Pd-Pt, Cu-Pd and Ag-Au) on TiNs modify the interface and hence electronic structure of MNPs/TiNs. • The bimetallic nanoparticles crafted TiNs induce compressive strains that improve the charge separation at the interface. • Photocatalytic light harvesting of compressively strained Ag-Au/TiNs system is better than Cu-Pd/TiNs and Pd-Pt/TiNs. One dimensional oxide-based hybrid nanostructures have immense potential for next generation energy applications. By considering that, the present work dwells into interfacial interaction in strain induced bimetallic nanoparticles-TiO 2 nanohybrids for photo energy harvesting. The hybrid nanostructure system consists of bimetallic nanoparticles (Pd-Pt, Cu-Pd, Ag-Au)/TiO 2 nanostructures (MNPs/TiNs). The different pathways are used to craft Cu-Pd and Pd-Pt on TiNs in comparison to Ag-Au. The crafting of MNPs on TiNs has been found effectual to modify the interface and hence electronic structure of MNPs/TiNs as evident by X-ray photoelectron spectroscopy (XPS). The detailed analysis in to the strains induced in the hybrid system is investigated using micro-Raman spectroscopy and is corroborated with X-ray diffraction (XRD) and XPS studies. The analysis revealed that the crafting of the bimetallic nanoparticles in the TiNs induce compressive strains that improve the charge separation at the interface. The strain induced hybrids are further explored for photocatalysis. It is observed that overall photocatalytic light harvesting of compressively strained Ag-Au/TiNs system is better than Cu-Pd/TiNs and Pd-Pt/TiNs owing to better charge separation at the interface. The time dependence of the photo-degradation using a model compound is also studied and the system is found to be following pseudo-first order kinetics. [ABSTRACT FROM AUTHOR]