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We report the unambiguous demonstration of controlled quantum well intermixing (QWI) in the technologically important GaInNAs/GaAs 1.3 μm material system. QWI is a key technique to selectively modify the band gap of quantum wells, which has found broad application in semiconductor lasers and photonic integrated circuits (PICs). Extending such technology to GaInNAs/GaAs structures is highly desirable due to the technologically advantageous properties of this material system. Here, we investigate well-characterized GaInNAs quantum well material which has been annealed “to saturation” before QWI processing to allow unambiguous interpretation of results. After RTA at 700 °C for ∼180 s, controlled shifts in band-gap at room temperature of up to 200 nm have been observed in sputtered SiO2-capped samples, whilst uncapped and PECVD SiO2-capped samples demonstrated negligible shift. This selective modification of the band gap has been confirmed by detailed photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy. Analysis of composition profile by SIMS revealed that the QWI is due to the interdiffusion of In–Ga between the quantum wells and the barriers enhanced by the point defects generated during the sputtering process. Investigation of a series of samples of differing N concentrations will be presented, which provides extra information about the intrinsic properties of GaInNAs. [Copyright &y& Elsevier]

• Defects in the selective contacts affect the transport mechanism in solar cells. • The density of states (DOS) of the transition metal oxides is unexplored. • The deconvolution of the absorption spectra is a viable method for extrapolating the DOS. • DOS distributions and small polaron parameters extrapolated for thin films of MoO 3. Thin layers of MoO x have been deposited by thermal evaporation followed by post-deposition annealing. The density of states distributions of the MoO x films were extracted deconvoluting the absorption spectra, measured by a photothermal deflection spectroscopy setup, including the small polaron contribution. Results revealed a sub-band defect distribution centered 1.1 eV below the conduction band; the amplitude of this distribution was found to increase with post-deposition annealing temperature and film thickness. [ABSTRACT FROM AUTHOR]

Abstract ZnO thin films were deposited by home-made DC sputtering of zinc target under mixed gases (Argon, Oxygen) plasma on glass substrates. Films were deposited by varying oxygen partial pressure (PO 2) from 0.09 to 1.3 mbar in the deposition chamber, at a fixed substrate temperature of 100 °C. The samples were characterized by photoluminescence (PL), X-ray diffraction (XRD), optical transmissions (UV–vis), scanning electron microscopy (SEM) and electrical (Hall effect) measurements. The results indicate that by varying the oxygen pressure in the deposition chamber, the films show a precise and well defined photoluminescence emissions for each range of pressure covering almost the entire visible domain (UV, UV-Violet, Violet, Blue, and Red) with high intensities. Moreover, the deposited films have different defects levels. The XRD analysis indicates that the films are well grown along the c-axis peak, but with different crystalline quality. Optical measurements reveal a high transmission, up to 90%, in the spectral region between 400 and 2500 nm and a large variation of the optical band gap (3.16–4.34 eV). As an application of the deposited ZnO films, the photo-catalytic degradation of a synthetic solution of Rhodamine B (RhB) poured on a ZnO thin film was successfully achieved and an elimination rate of 38% was obtained after exposing the film to solar light for 3 h. [ABSTRACT FROM AUTHOR]

The thickness of vanadium dioxide (VO 2) films is a crucial parameter for the study of their optical and thermal properties. In this paper we studied the effect of the film thickness on the thermal hysteresis loop during the phase transition of VO 2 deposited on a sapphire substrate by pulsed laser deposition (PLD), by the application of the Infrared Thermography technique. We measure the main thermal hysteresis parameters of VO 2 samples with different thicknesses in the LWIR range (8–14 μm) showing how the transition temperature during the heating and cooling cycles, and the width of the hysteresis loop, may change with thickness. We analyzed and compared the obtained results with, in situ Grazing Incidence X-Ray Diffraction (GI-XRD). A good agreement between the results obtained with the two techniques was found demonstrating the reliability of the IR Thermography as a quantitative characterization tool. The results show that the structural and IR emissivity properties of the VO 2 layer exhibit a dynamic range dependent on the layer thickness due to a correlation with the crystalline grain size. This has important effects in view of a tailored energy management for the use of those materials as smart radiators or smart windows. [Display omitted] • Infrared Thermography is revealed as a powerful quantitative imaging tool to detect the semiconductor to metal transition of thermochromic VO 2 thin films deposited on sapphire by PLD. • Experimental results from both Infrared Thermography and Grazing Incidence XRD show strong correlated thermal hysteresis loops across the transition from monoclinic to rutile phase. • Transition temperature, transition width, and hysteresis loop parameters change with the layer thickness (from 50 to 700 nm) and with the grain size of crystallites (from 20 to 40 nm). A quantitative correlation is here shown. • The results are fundamental for designing smart radiators and windows, where the emissivity should be controlled for tailored energy management. [ABSTRACT FROM AUTHOR]

• Cheap and easily customisable memristors electrical characterisation system. • Capability of performing retention, endurance and DC sweeps measurements. • Capability of imposing a fine-tuneable current compliance. A cheap, compact and customisable characterisation system for memristor devices, working between ± 10 V, is presented. SPICE (Simulation Program with Integrated Circuit Emphasis) simulations are performed to verify the circuit feasibility and a proper software is developed to drive the system. The potentiality of the realised system is tested by performing several electrical measurements on both Cu/HfO 2 /Pt memristors and two-terminals commercial devices. [ABSTRACT FROM AUTHOR]

We report the use of GaInNAs/GaAs material system for a range of 1.3 μm vertical-cavity devices namely VCSELs, VCSOAs, VECSELs and SESAMs. Using optical pumping, we demonstrate that up to 4 mW of 1290 nm output power can be fibre-coupled from a VCSEL. We also show that tayloring the VCSEL structure allows to produce a monolithic long-wavelength VCSOA with up to 16 dB of gain. We also report the first demonstration of a 1.3 μm VECSEL with more than 0.5 W of CW ouptut power. Finally, annealing effects on the properties of a GaInNAs SBR and modelocking of two Nd:doped solid state lasers using this element are described. [Copyright &y& Elsevier]