Spectral Emissivity and Thermal Conductivity Properties of Black Aluminum Films.

Black aluminum is a material characterized by high surface porosity due to columnar growth and exhibits unique optical properties that make it attractive for applications such as light trapping, infrared detection, and passive thermal radiation cooling. In this study, we correlate the structural and optical properties of black aluminum by comparing it with conventional reflective aluminum layers. These layers of varying thicknesses were deposited on fused silica substrates, and their optical properties were analyzed.

Correction: Photoluminescence modification of europium(III)-doped MAlO (M = Zn, Mg) spinels induced by Ag@SiO core-shell nanoparticles.

Correction for 'Photoluminescence modification of europium(III)-doped MAlO (M = Zn, Mg) spinels induced by Ag@SiO core-shell nanoparticles' by Rodrigo A. Valenzuela-Fernández , , 2024, https://doi.org/10.

Photoluminescence modification of europium(III)-doped MAlO (M = Zn, Mg) spinels induced by Ag@SiO core-shell nanoparticles.

In recent years, there has been an increasing interest in developing new inorganic compounds with exceptional properties for advanced materials. Specifically, compounds containing europium have attracted much attention due to their luminescent properties. These compounds are used in electronics, biotechnology, medicine, and catalysis.

Identification of (Tb,Eu)(SiO)O Oxy-Apatite Structures as Nanometric Inclusions in Annealed (Eu,Tb)-Doped ZnO/Si Junctions: Combined Electron Diffraction and Chemical Contrast Imaging Studies.

(Tb,Eu)-doped ZnO-annealed films at 1100 °C showed intense photoluminescense (PL) emission from Eu and Tb ions. The high-temperature annealing led to a chemical segregation and a secondary Zn-free phase formation that is suspected to be responsible for the high PL intensity. Large faceted inclusions of rare-earth (RE) silicates of a size of few hundred nanometers were observed.

Toward RGB LEDs based on rare earth-doped ZnO.

By using ZnO thin films doped with Ce, Tb or Eu, deposited via radiofrequency magnetron sputtering, we have developed monochromatic (blue, green and red, respectively) light emitting devices (LEDs). The rare earth ions introduced with doping rates lower than 2% exhibit narrow and intense emission peaks due to electronic transitions in relaxation processes induced after electrical excitation. This study proves zinc oxide to be a good host for these elements, its high conductivity and optical transparency in the visible range being as well exploited as top transparent electrode.

Simultaneous detection of trace Ag(I) and Cu(II) ions using homoepitaxially grown GaN micropillar electrode.

Driven by the motivation to quantitively control and monitor trace metal ions in water, the development of environmental-friendly electrodes with superior detection sensitivity is extremely important. In this work, we report the design of a stable, ultrasensitive and biocompatible electrode for the detection of trace Ag and Cu ions by growing n-type GaN micropillars on conductive p-type GaN substrate. The electrochemical measurement based on cyclic voltammetry indicates that the GaN micropillars exhibit quasi-reversible and mass-controlled reaction in redox probe solution.

Tunneling Atomic Layer-Deposited Aluminum Oxide: a Correlated Structural/Electrical Performance Study for the Surface Passivation of Silicon Junctions.

Passivation is a key process for the optimization of silicon p-n junctions. Among the different technologies used to passivate the surface and contact interfaces, alumina is widely used. One key parameter is the thickness of the passivation layer that is commonly deposited using atomic layer deposition (ALD) technique.

High-resolution STEM-HAADF microscopy on a γ-AlO supported MoS catalyst-proof of the changes in dispersion and morphology of the slabs with the addition of citric acid.

Atomic-scale images of MoS slabs supported on γ-AlO were obtained by high-resolution scanning transmission electron microscopy equipped with a high angular annular dark field detector (HR STEM-HAADF). These observations, obtained for sulfide catalysts prepared with or without citric acid as a chelating agent, evidenced variations in morphology (shape) and size of the MoS nanoslabs, as detected indirectly by the adsorption of CO followed by infrared spectroscopy. Quantitative dispersion values and a morphology index (S-edge/M-edge ratio) were determined from the slabs observed.

Cross-Correlation between Strain, Ferroelectricity, and Ferromagnetism in Epitaxial Multiferroic CoFeO/BaTiO Heterostructures.

Multiferroic biphase systems with robust ferromagnetic and ferroelectric response at room temperature would be ideally suitable for voltage-controlled nonvolatile memories. Understanding the role of strain and charges at interfaces is central for an accurate control of the ferroelectricity as well as of the ferromagnetism. In this paper, we probe the relationship between the strain and the ferromagnetic/ferroelectric properties in the layered CoFeO/BaTiO (CFO/BTO) model system.

Enhanced photovoltaic performance of inverted polymer solar cells through atomic layer deposited AlO passivation of ZnO-nanoparticle buffer layer.

In this work, an atomic layer deposited (ALD) AlO ultrathin layer was introduced to passivate the ZnO-nanoparticle (NP) buffer layer of inverted polymer solar cells (PSCs) based on P3HT:PCBM. The surface morphology of the ZnO-NP/AlO interface was systematically analyzed by using a variety of tools, in particular transmission electron microscopy (TEM), evidencing a conformal ALD-AlO deposition. The thickness of the AlO layers was optimized at the nanoscale to boost electron transport of the ZnO-NP layer, which can be attributed to the suppression of oxygen vacancy defects in ZnO-NPs confirmed by photoluminescence measurement.

Local Schottky contacts of embedded Ag nanoparticles in AlO/SiN :H stacks on Si: a design to enhance field effect passivation of Si junctions.

This paper describes an original design leading to the field effect passivation of Si n-p junctions. Ordered Ag nanoparticle (Ag-NP) arrays with optimal size and coverage fabricated by means of nanosphere lithography and thermal evaporation, were embedded in ultrathin-AlO/SiN :H stacks on the top of implanted Si n-p junctions, to achieve effective surface passivation. One way to characterize surface passivation is to use photocurrent, sensitive to recombination centers.

The nitrogen concentration effect on Ce doped SiON emission: towards optimized Ce for LED applications.

Ce-Doped SiON films are deposited by magnetron reactive sputtering from a CeO target under a nitrogen reactive gas atmosphere. Visible photoluminescence measurements regarding the nitrogen gas flow reveal a large emission band centered at 450 nm for a sample deposited under a 2 sccm flow. Special attention is paid to the origin of such an emission at high nitrogen concentration.

Alignment control and atomically-scaled heteroepitaxial interface study of GaN nanowires.

Well-aligned GaN nanowires are promising candidates for building high-performance optoelectronic nanodevices. In this work, we demonstrate the epitaxial growth of well-aligned GaN nanowires on a [0001]-oriented sapphire substrate in a simple catalyst-assisted chemical vapor deposition process and their alignment control. It is found that the ammonia flux plays a key role in dominating the initial nucleation of GaN nanocrystals and their orientation.

Impurity-Governed Modification of Optical and Structural Properties of ZrO-Based Composites Doped with Cu and Y.

The influence of calcination temperature on copper spatial localization in Y-stabilized ZrO powders was studied by attenuated total reflection, diffuse reflectance, electron paramagnetic resonance, transmission electron microscopy, electron energy loss, and energy-dispersive X-ray spectroscopies. It was found that calcination temperature rise in the range of 500-700 °C caused the increase of copper concentration in the volume of ZrO nanocrystals. This increase was due to Cu in-diffusion from surface complexes that contained copper ions linked with either water molecules or OH groups.

Structural and emission properties of Tb-doped nitrogen-rich silicon oxynitride films.

Terbium doped silicon oxynitride host matrix is suitable for various applications such as light emitters compatible with CMOS technology or frequency converter systems for photovoltaic cells. In this study, amorphous Tb ion doped nitrogen-rich silicon oxynitride (NRSON) thin films were fabricated using a reactive magnetron co-sputtering method, with various N flows and annealing conditions, in order to study their structural and emission properties. Rutherford backscattering (RBS) measurements and refractive index values confirmed the silicon oxynitride nature of the films.

Microstructure and optical properties of Pr3+-doped hafnium silicate films.

In this study, we report on the evolution of the microstructure and photoluminescence properties of Pr3+-doped hafnium silicate thin films as a function of annealing temperature (TA). The composition and microstructure of the films were characterized by means of Rutherford backscattering spectrometry, spectroscopic ellipsometry, Fourier transform infrared absorption, and X-ray diffraction, while the emission properties have been studied by means of photoluminescence (PL) and PL excitation (PLE) spectroscopies. It was observed that a post-annealing treatment favors the phase separation in hafnium silicate matrix being more evident at 950°C.

Structural and optical characterization of pure Si-rich nitride thin films.

The specific dependence of the Si content on the structural and optical properties of O- and H-free Si-rich nitride (SiNx>1.33) thin films deposited by magnetron sputtering is investigated. A semiempirical relation between the composition and the refractive index was found.

Studies of non-vacuum processing of Cu-chalcogenide thin films.

Cu-chalcogenide thin films were prepared using a two stage method: one step electrodeposition of CuISe and CIGSe, and the sulfurisation of CISe to prepare CISSe thin films. The films were deposited on different substrates: Mo and ITO coated glass. The optimum potentials for electrodeposition of CISe and CIGSe films were respectively selected in the range -400 to -550 mV and -650 to -700 mV (vs.

Thickness-dependent optimization of Er3+ light emission from silicon-rich silicon oxide thin films.

This study investigates the influence of the film thickness on the silicon-excess-mediated sensitization of Erbium ions in Si-rich silica. The Er3+ photoluminescence at 1.5 μm, normalized to the film thickness, was found five times larger for films 1 μm-thick than that from 50-nm-thick films intended for electrically driven devices.

Effect of the Nd content on the structural and photoluminescence properties of silicon-rich silicon dioxide thin films.

In this article, the microstructure and photoluminescence (PL) properties of Nd-doped silicon-rich silicon oxide (SRSO) are reported as a function of the annealing temperature and the Nd concentration. The thin films, which were grown on Si substrates by reactive magnetron co-sputtering, contain the same Si excess as determined by Rutherford backscattering spectrometry. Fourier transform infrared (FTIR) spectra show that a phase separation occurs during the annealing because of the condensation of the Si excess resulting in the formation of silicon nanoparticles (Si-np) as detected by high-resolution transmission electron microscopy and X-ray diffraction (XRD) measurements.

Thermal stability of high-k Si-rich HfO(2) layers grown by RF magnetron sputtering.

The microstructure and optical properties of HfSiO films fabricated by RF magnetron sputtering were studied by means of x-ray diffraction, transmission electron microscopy, spectroscopic ellipsometry and attenuated total reflection infrared spectroscopy versus annealing treatment. It was shown that silicon incorporation in the HfO(2) matrix plays an important role in the structure stability of the layers. Thus, the increase of the annealing temperature up to 1000 degrees C did not lead to the crystallization of the films.

The role of atomic scale investigation in the development of nanoscale materials for information storage applications.

It is well established that the response of devices based on the giant magnetoresistance (GMR) effect depends critically on film microstructure, with parameters such as interfacial abruptness, the roughness and waviness of the layers, and grain size being crucial. Such devices have applications in information storage systems, and are therefore of great technological interest as well as being of fundamental scientific interest. The layers must be studied at high spatial resolution if the microstructural parameters are to be characterized with sufficient detail to enable the effects of fabrication conditions on properties to be understood, and the techniques of high resolution electron microscopy, transmission electron microscopy chemical mapping, and atom probe microanalysis are ideally suited.

In Situ Transmission Electron Microscopy Studies of the Magnetization Reversal Mechanism in Information Storage Materials.

: The Foucault and Fresnel modes of Lorentz microscopy, together with a quantitative magnetization mapping technique, summed image differential phase-contrast imaging, were used to study the magnetization reversal mechanism of the sense layer in spin-valve structures exhibiting the giant magnetoresistance effect. In addition to studies of sheet film, lithographically defined spin-valve elements were investigated. A current can be passed through the element during magnetizing so that the effect of the applied current on the giant magnetoresistance and magnetization reversal mechanism can be studied.