In this study, we successfully demonstrate a carrier-injection InGaAsP variable optical attenuator (VOA) with a lateral P-I-N junction formed by Ni-InGaAsP alloy and Zn diffusion on a III-V on insulator (III-V-OI) wafer. The Ni-InGaAsP alloy for the n+ junction is formed by direct reaction between Ni and InGaAsP after annealing at 350°C. The p+ junction is formed by the Zn diffusion at 500°C using Zn doped spin-on glass (SOG). By both techniques, we successfully reduce the sheet and contact resistivity in the lateral P-I-N junction even with the relatively low-temperature process as compared with the P-I-N junction formed by conventional Si and Be ion implantation. By injecting carriers into the InGaAsP waveguide through the lateral P-I-N junction, we achieve the optical attenuation of -40 dB/mm with an injection current density of 40 mA/mm at a 1.55 μm wavelength.

In-situ ion irradiation and transmission electron microscopy has been used to examine the effects of the He appm to DPA ratio, temperature and dose on the damage structure of tungsten (W). Irradiations were performed with 15 or 60 keV He+ ions, achieving He-appm/displacements per atom (DPA) ratios of ∼40,000 and ∼2000, respectively, at temperatures between 500 and 1000°C to a dose of ∼3 DPA. A high number of small dislocation loops with sizes around 5–20 nm and a He bubble lattice were observed for both He-appm/DPA ratios at 500°C with a bubble size ∼1.5 nm. Using the g.b =0 criterion the loops were characterised as b = ±1/2<111> type. At 750°C bubbles do not form an ordered array and are larger in size compared to the irradiations at 500°C, with a diameter of ∼3 nm. Fewer dislocation loops were observed at this temperature and were also characterised to be b = ±1/2<111> type. At 1000°C, no dislocation loops were observed and bubbles grew as a function of fluence attributed to vacancy mobility being higher and vacancy clusters becoming mobile.

Polycrystalline <100 nm thin CdS films deposited by the chemical bath deposition (CBD) method are used as n-type window layer in high efficiency heterojunction CuInSe2, Cu2ZnSnS4, and CdTe solar cells. The major shortcoming of the CdS films is its stability and high sub-bandgap absorption. In the present work, an alternative window layer for the heterojunction solar cells based on cadmium oxysulfide Cd(S,O) thin films formed by the CBD method is described. The ∼100 nm thin Cd(S,O) films formed by co-deposition of CdS with CdO show high >85% optical transmittance over 550-1000 nm region compared to 70% transmission in CdS films. Cd(S,O) film formed with highly conformal coverage showed as direct optical band gap of 2.19-2.09 eV depending on the CdO fraction in the film. The CBD growth of CdS is via controlled release of S2- and Cd2+ ions in an alkaline medium through complexing to prevent CdS or Cd(OH)2 as colloids in the solution phase. In the present method, by altering the substrate conditions we carried out controlled Cd(OH)2 deprotonation reaction to form CdO over the substrate concurrently with CdS to deposit Cd(S,O) films. These films are polycrystalline having wurtzite structure identified by (002), (110) and (112) x-ray diffractions. Formation of Cd(S,O) phase is confirmed by Raman spectra which besides the characteristic CdS 1LO and 2LO modes at 300 and 600 cm-1, also showed Raman lines from CdO at 1094 cm-1 and 943 cm-1 assigned as overtone of 2LO phonon modes at the L or Γ points of the Brillouin zone of CdO.

A simplified procedure of synthesizing nano-sized hollow silicate particles (NHSPs) of 80-200 nm in average diameter and approximately 30 nm in wall thickness via (soft template) soluble-poly(methacrylic acid) sodium salt (NaPMA) is presented here. The process is easily scalable and can be carried out at ambient temperature. When deposited as thin (nanolayer) film, NHSPs show good transparency in visible spectra range and good sorption of CO2 for thermal energy efficiency especially in the field of thermal insulation application.

The present work accentuates the effect of UV laser irradiation on theconductivity of nickel oxide (NiO) thin films, deposited at various temperaturesby radio-frequency reactive sputtering of Ni in oxygen containing atmosphere.The effect of UV irradiation on zinc oxide – nickel oxideheterostructures, obtained by sputtering, was examined as well. It was foundthat the resistivity of NiO changes from 12 Ω-cm to 0.62Ω-cm, and the majority carrier concentration from3.95x1017 holes/cm3 to 4.22x1020electrons/cm3. The current-voltage (I-V) characteristics of theZnO/NiO heterostructure shows an improved p-n diode behavior with the forwardbias current increasing for the laser-irradiated ZnO/NiO compared to theas-deposited stack. The observed improvement in diode-like behavior suggeststhat laser irradiation can be an important technique to controllably change thestructural, electrical and optical properties of metal oxide thin films.

Titania nanotubes were prepared by anodic oxidation of Ti. The titania surfaces were partially coated with Zn by reacting zinc acetate with the nanotubes and then annealed. [1] An annealed nanotube cluster was placed carefully on a silicon wafer using tweezers. Secondary electron images were acquired by bombarding with Cs+ and observing the ejected OZn- and OTi- respectively. The SIMS analysis was done in ultra-high vacuum (∼ 10-10 Torr). The location of before and after the SIMS analysis was confirmed by scanning electron microscopy (SEM). Specific areas with various orientations (vertical and horizontal orientations) of the nanotubes were selected for the NanoSIMS 50L analysis. The NanoSIMS 50L is made by Ametek Cameca, Gennevillieres, France and is capable of doing in situ isotopic analysis of surfaces at high spatial resolution (25 nm2). The average ZnO/TiO was ∼1.8%, confirming the actual content of Zn used during synthesis of the nanotubes. Qualitatively, the TiO/ZnO ratio increased with increasing depth implying that ZnO concentration was decreasing as we probed into the nanotubes.

Solution-processed zinc oxide (ZnO) thin-film transistors (TFTs) obtained viahydrolysis/pyrolysis of an organic precursor present an excellent technique toobtain high performance electronic devices with low manufacturing cost. In thecurrent work, we propose the use of an alternative deposition method, based on apolymeric precursor route (known as Pechini), to obtain solution-processed ZnOcompact films as the active layer of TFTs. The elimination of the organic phaseand the formation of inorganic thin-films was carried out by thermal treatmentat different temperatures (ranging from 200°C to 500°C) and atdifferent times (from 5 min to 2 hours), being monitored by UV-vis and infrared(IR) optical absorption spectroscopy. It was observed that, for temperaturesabove 400°C and treatment times superior to 30 min, the organic phasewas completely eliminated, remaining only the inorganic (metal oxide) phase. Theoptical bandgap of the resulting ZnO films, determined from UV-vis absorption,is about 3.4 eV. The electrical characteristics (output and transfer curves) ofthe obtained devices demonstrate the feasibility of Pecchini method to buildsolution-processed metal oxide TFTs. The results for the electrical mobility ofthe majority charge-carriers (electrons) and for the threshold voltage were 0.39cm2.V-1.s-1 and 0.45 V, respectively.

Gas Technology Institute (GTI), together with its partners University of California at Merced (UC Merced) and MicroLink Devices Inc. (MicroLink) are developing a full spectrum solar energy collection system to deliver variable electricity and on-demand heat. The technology uses secondary optics in a solar receiver to achieve high efficiency at high temperature, collects heat in particles for low fire danger, stores heat in particles instead of molten salt for low cost, and uses double junction (2J) photovoltaic (PV) cells with backside infrared (IR) reflectors on the secondary optical element to raise exergy efficiency. The overall goal is to deliver enhancement to established trough technology while exceeding the heliostat power tower molten salt temperature limit. The use of inert particles for heat transfer may make parabolic troughs safer near population centers and may be valuable for industrial facilities.

For optoelectronic device applications, quantum wires can be used as active media due to their unique physical properties. However, conventional approaches such as the self-assembly via the Stranski-Krastanov (S-K) growth technique have a limited success in their applications toward optoelectronic devices including photovoltaics and solar cells. A novel fabrication mechanism for quality quantum wires has been discovered. The laser fabricated nanowires semiconductor surfaces can have width and height as small as 30 and 5 nm, respectively while the density is one per 200 nm.

At the MRS Fall 2014 Meeting, Symposium E, we reported on morphologies, fragmentation, and hardness in synthetic hydrogen urate monohydrate (monosodium urate monohydrate, MSUM, or MSU) crystals. We are now presenting further characterization results, including some from the biomaterial that forms in humans with gout disease: The fanning of radiating blades (needles) in spherulitic grains of synthetic MSUM was examined by microscopy techniques. These and previous data are consistent with an interpretation in terms of the crystallographic parameters in the unit cell, and the presence of dislocation arrays at low angle boundaries. The kinetics of such branched growth is here related to thermodynamic properties and super-saturation levels. Secondary nucleation is an additional mechanism leading to more complex morphologies. Differences in overall growth rates, under conditions of either branched or single needle growth, are considered in relation to gout. Novel powder XRD and solid state NMR data show, respectively, preferred orientation in the biomaterial, and the potential of NMR for identifying and characterizing MSUM in specific environments, helping to resolve pending questions in gout. Present results are anticipated to be useful for designing bio-inspired and bio-mimetic materials, regarding morphologies, overall growth rates, and mechanical properties.

An electrochemical glucose sensor based on zinc oxide (ZnO) nanorods is fabricated, characterized and tested. The ZnO nanorods are synthesized on indium titanium oxide (ITO) coated glass substrate, using the hydrothermal sol-gel technique. The working principle of the sensor under investigation is based on the electrochemical reaction taking place between cathode and anode, in the presence of an electrolyte. A platinum plate, used as the cathode and Nafion/Glucose Oxidase/ZnO nanorods/ITO-coated glass substrate used as anode, is immersed in pH 7.0 phosphate buffer solution electrolyte to test for the presence of glucose. Several amperometric tests are performed on the fabricated sensor to determine the response time, sensitivity and limit of detection of the sensor. A fast response time less than 3 s with a high sensitivity of 1.151 mA cm-2mM-1 and low limit of detection of 0.089 mM is reported. The glucose sensor is characterized using the cyclic voltammetry method in the range from -0.8 – 0.8 V with a voltage scan rate of 100 mV/s.

The optical properties of RF sputtered polycrystalline permalloy oxide (PyO) thin films were studied in the infrared by variable angle ellipsometry. The dispersion of PyO shows a Lorentzian dispersion peak at 381.5 cm-1. We attribute this peak to the transverse optical phonon of PyO. This peak is consistent with a rocksalt crystal structure for the Ni0.81Fe0.19O1-δ thin films.

We established a Ca1-xBixMn1-yNiyO3 (0 ≤ x, y ≤ 0.1) powder library using a combinatorial system based on the electrostatic spray deposition method. Single phase perovskite-type structures were identified in all of the powders. To measure electrical conductivity, the powder library was subjected to high-pressure (200 MPa) and heat-treated at 950°C for 1 hour in an oxygen atmosphere. As a representative example, the electrical conductivity of 5%-Bi-substituted CaMnO3-δ showed a higher value (63 S·cm-1) than an unsubstituted powder (13 S·cm-1). The improved electrical conductivity, on the other hand, was still very far from the ideal result (167 S·cm-1).

The presence of the C- and A-type orbital-ordered states has been reported in thehighly-correlated electronic systemSr1-xNdxMnO3 (SNMO). The interesting feature ofthe oxide system is that an increase in the Nd content leads to the (C-type→ A-type) state change across a temperature-independent morphotropicphase boundary (MPB). Although structural fluctuations can be expected near theMPB, the detailed features of the state change have not been understoodsufficiently. Thus, the crystallographic features of the state change in SNMOwith 0.35 ≤ x ≤ 0.49 have been investigated mainly at 300K, by x-ray powder diffraction and transmission electron microscopy. It wasfound that the C-type orbital-ordered state with the tetragonal-I4/mcm symmetryand the disordered orthorhombic-Imma state were present for 0.35 ≤ x≤ 0.43 and for 0.45 ≤ x ≤ 0.49 at 300 K,respectively. The notable feature of the state change is that disordered regionswith the cubic-Pm $\bar 3$ m symmetry were also found locally for x= 0.43, in addition to the C-type state. Because therotational-displacement pattern for oxygen octahedra involved in thedisordered-Imma state is the same as that in the A-type state, furthermore, theformer disordered state may be regarded as a precursor state to the A-typeorbital ordering.

We introduce a new set of multifunctional metal-coordinating polymers as ligands for the surface functionalization of three different inorganic nanocrystals: luminescent quantum dots (QDs), magnetic iron oxide nanocrystals and metal gold nanoparticles. The ligand design relies on the introduction of a large but controllable number of anchoring groups, hydrophilic moieties and reactive functionalities all in the same polymer chain, via a one-step nucleophilic addition reaction. Nanocrystals capped with these polymer ligands exhibit long-term stability over a broad range of biological conditions. Furthermore, when zwitterion groups are introduced as hydrophilic blocks, this yields a compact ligand coating that allows conjugation of biomolecules to the nanocrystals via metal-histidine self-assembly. The resulting hydrophilic nanocrystals have been used to develop a few specific sensing platforms targeting soluble iron ions and cysteine.

In this paper, we demonstrate an organic electrochemical transistor (OECT) based on the conductive polymer PEDOT:PSS for the analysis of the cell culture medium upon interaction with circulating cells isolated form peripheral blood sampling of health, sub-clinical and cancer patients. The device comprises arrays of super-hydrophobic micro-pillars in which a finite number of pillars incorporates nano-electrodes for site specific measurements of a solution. Due to its nano-scale architecture, the device realizes time and space resolved measurement of biological solution. Tumor metabolism could produce reactive species able to determine a different electronic behavior of correspondent microenviroment. On this basis, the device here presented the changes in the ESR signals was used to identify electronic changes occurring in the analysis of different type of microenvironment. Our results demonstrate that the device is able to register significative difference to differentiate healthy individuals form cancer patients, through an easy blood sampling. In conclusion, these preliminary data are suggestive of a novel test potentially useful to early identification of subjects at risk to development cancer disease.

The search for high-efficiency and environmentally benign water splitting catalysts has been on the rise since this process is a source of renewable, clean energy. However the process is inherently slow, especially for the production of O2 from H2O (water oxidation) due to the high electron count and energy intensive bond formation of the reaction. Hence the search for novel catalysts for oxygen evolution reactions (OER) has led researchers to focus on various families of compounds including oxides and recently selenides. Multifunctional nanostructures containing the semiconductor electrocatalyst grafted onto an optically active metallic component might boost the catalytic activity even further due to efficient charge injection. Magnetically active catalysts will also be lucrative since that might induce better adhesion of the oxygenated species at the catalytically active site. In this report we introduce multifunctional, magnetic Au3Pd–CoSe nanostructures as high-efficiency OER electrocatalysts. These multifunctional nanostructures were synthesized by a chemical vapor deposition (CVD) reaction with cobalt acetylacetonate and elemental selenium on Au-Pd sputter coated silica substrate at 800°C. The morphology of these multifunctional nanostructures were mostly bifunctional Janus-like nanoparticles as seen through scanning and transmission electron microscopy. They also showed soft ferromagnetic behavior. These bifunctional nanoparticles were coated on the anodes of a water oxidation cell and it was observed that these nanoparticles showed a higher OER activity with lower onset potential for O2 evolution as compared to the conventional oxide-based OER electrocatalysts.

For optoelectronic application, two-dimensional materials such as molybdenum disulfide (MoS2) are very promising candidate with their interesting electronic and optical properties. The layered structure of these materials makes them amenable to mechanical exfoliation to form scalable 2D atomic crystals. For width range of applications, liquid phase exfoliation using sonication and centrifugation in appropriate solvent is needed. This simple and scalable technique gives high quality of exfoliation of 2D materials without chemical reactions. In this paper, we report an example of the optical and electronic characterizations on MoS2 synthesized by liquid exfoliation in specific solvent.

ErxYb(3-x)Q9 (1, x = 1, 2), NdYb2Q9 (2), NdEr2Q9 (3) and NdErYbQ9 (4), have been obtained through a simple molecular strategy, by controlling reactant stoichiometry. In 2-4, the templating effect of the molecular framework allows to control the metal distribution across the coordination sites where the central position is occupied by the larger Nd ion and the terminal ones by the almost vicariants Yb3+ and Er3+, drastically reducing molecular speciation. Remarkably, 4 represents the first example of a discrete molecular entity containing three different Ln ions simultaneously emitting in three different spectral regions in the NIR, upon single visible wavelength excitation. Highly transparent and homogeneous doped silica glasses have been prepared, which show the same optical properties of the incorporated complex in solution.