Optical Properties Of Aluminum Research Articles

Optical Properties of Aluminum- and Silicon-Nitride Films and Al–Si–N Nanocomposite Coatings Deposited by Reactive Magnetron Sputtering

In this paper, we study the optical properties of aluminum- and silicon-nitride films and Al–Si–N coatings with variable atomic composition deposited by reactive magnetron sputtering on glass, silicon, and steel substrates. The absorption and luminescence characteristics are determined by the composition of the coatings and microstructure and depend on the physical properties of the substrate. The absorption and luminescence centers are associated with intrinsic defects in the nitrides and their simplest complexes. The relationships between the accumulation of growth defects, their interaction, the type of distribution of localized states, the band gap, and the stability of the optical properties are established. At an increase in the silicon content in the coatings, the degree of static induced disorder increases, and the contribution of the continuous distribution of the defect levels and interband absorption increases. Silicon-containing defects stabilize the optical properties of the coatings.

The Influence of Temperature on the Spectral Dependences of Aluminum’s Optical Properties

Data in the literature on the optical properties of aluminum in the range of 198–1173 K are analyzed. Analytical expressions describing the dependences of aluminum permittivity on photon energy and temperature are proposed and tested. The spectral dependences of the aluminum absorption coefficient and specular reflectance at normal incidence, as well as of the absorption-efficiency coefficients of aluminum nanoparticles in a lithium-fluoride matrix, are calculated at different temperatures. The results obtained indicate the appearance of unusual nonlinear absorption effects in nanocomposites containing aluminum nanoparticles, which manifest themselves in a decrease in the absorption efficiency with increasing temperature at photon energies exceeding 1.40 eV.

Tuning the electronic and optical properties of XP(X = Al,Ga) monolayer semiconductors using biaxial strain effect: Modified Becke-Johnson calculations

In this paper, based on full potential density functional theory calculations, the electronic and optical properties of aluminium and gallium phosphide (AlP and GaP) graphene-like structures are investigated under different biaxial compressive and tensile strain loads. One of the fascinating properties of these new monolayers is their high stretch-ability and high mechanosensitivity of their electronic and optical features. The electronic calculations display that the energy gap of materials versus the exerted strain can be estimated by a second order polynomial equation. Furthermore, the optical calculations indicate that the electronic and optical gap of AlP and GaP monolayers can be tuned by biaxial strain loads.

Temperature dependences of the optical properties of aluminum nanoparticles

The spectral dependences of the optical properties of aluminum at various temperatures have been analyzed. We have proposed and tested the approximation expressions for the imaginary part of the dielectric permittivity. The reflection coefficients at normal incidence of light and the optical properties of nanoparticles with a radius of 150 nm in a temperature range of 298–933 K have been calculated for practically important wavelengths. The optical properties of aluminum are found to be atypical, with the absorption coefficient decreasing with increasing temperature. This is due to the contribution of interband transitions to the optical properties of aluminum.

Electronic Structures and Optical Properties of Aluminum in Bulk, Thin Film and Nanoparticulate Forms

The electronic structures of aluminum in bulk, thin film and nanoparticle forms were calculated and compared in order to understand how the optical properties change with the dimensionality of the system. The band structure calculations were performed using the Vienna ab initio simulation package (VASP) based on the density functional theory (DFT)[1] and the projector augmented wave (PAW)-method.[2] We used an exchange-correlation potential Vxc within the generalized gradient approximation (GGA), where Vxc depends on the total electron density ρ(r) and the gradient of ρ(r), namely the Perdew-Burke-Ernzerhof (PBE) functional.[3] The calculated band structure diagrams for each of the three forms are shown in Figure 1. The z-direction was chosen as the direction along which periodicity of the lattice breaks down in going from bulk to thin film structure. In order to describe how the electronic structures of a periodic system evolve with spatial confinement, we have used tetragonal unit cells constructed from the lattice parameters of the conventional fcc unit cell in these calculations. Due to the absence of any bound d-like states, the progression from bands in the bulk to subbands in thin films and discrete energy levels in nanoparticles could be easily followed. Every energy band from the bulk splits into multiple bands for the thin films, referred to as subbands and discrete energy levels for nanoparticles. These subbands of the thin films can be noticed on comparing the lowest band between M and Γ points in the band structure plots of states associated with the bulk and thin films in Figure 1. The discrete structure of the energy levels along the kz -direction can be seen from the dispersion of the subbands along the Γ-Z direction. The nearly parabolic band along the Γ-Z direction in the bulk is replaced by a number of flat bands corresponding to discrete energy levels resulting from the confinement along the Z-direction. The density of states (DOS) and partial density of states (PDOS) were also calculated and will be discussed from the perspective of optical properties of this metal. Figure 2 shows the calculated values of the imaginary part of the dielectric function, ε 2 , as the system changes from bulk to thin film to particle. The free electron contribution is not included, and the peaks are due to interband transitions entirely. For the bulk case, the minor peaks at E > 2 eV appear to be varying randomly and are probably artifacts of calculation. Most likely there are only two meaningful peaks, one being at 0.5 eV and the other at 1.5 eV. For the thin film in the x-direction, ε 2 has a form that is somewhat similar to that seen in the bulk with a slight shift in the lower energy peak. This similarity is expected since the system in not confined in the x- or y-direction. On the other hand, ε 2 for the thin film in the z-direction exhibits a broad peak at ~1 eV and another peak at ~2 eV, which is significantly different from either the bulk or thin film in the x-direction. Finally, Figure 2 also shows ε 2 for the nanoparticles, and with confinement in all directions, the shape of the function differs from both the bulk or thin film case. In this talk, we will discuss the optical properties of this interesting metal based on our calculations, and the effect of spatial confinement.

Experimental Investigations of Thermal Joining of Polyamide Aluminum Hybrids Using a Combination of Mono- and Polychromatic Radiation

In recent years, the joining of plastics and metals for lightweight constructions has become more and more important for industrial applications. This paper presents experimental investigations of transmission joining of polyamide aluminum hybrids using a combination of mono- and polychromatic radiation. The used experimental setup consists of a diode laser, a laser processing head with additional infrared emitters, a robot and a clamping device for lap joints. With this setup, experiments are performed to determine a process window for the thermal joining of polyamide aluminum hybrids and to evaluate geometrical, material-related and process-related limits of the approach. For that, hybrid joints of aluminum with sheet thicknesses of 0.6 mm to 1.0 mm and 3mm thick unfilled polyamide 6 are used. To improve the mechanical interlocking between the polyamide and the aluminum surface a prior laser structuring of the metal is done by a ns-Nd:YAG-laser. Primarily,the influence of surface roughness and surface enlargement on the optical properties of aluminum and the mechanical properties of the joined specimens is investigated.

Structural, Electrical and Optical Properties of Aluminum Doped Zinc Oxide Spin Coated Films Made Using Different Coating Sols

Structural, Electrical and Optical Properties of Aluminum Doped Zinc Oxide Spin Coated Films Made Using Different Coating Sols

Ab initio calculation of transport and optical properties of aluminum: Influence of simulation parameters

This work is devoted to the ab initio calculation of transport and optical properties of aluminum. The calculation is based on the quantum molecular dynamics simulation, density functional theory and the Kubo–Greenwood formula. Mainly the calculations are performed for liquid aluminum at near-normal densities for the temperatures from melting up to 20,000K. The results on dynamic electrical conductivity, static electrical conductivity and thermal conductivity are obtained and compared with available reference and experimental data and the calculations of other authors. The influence of the technical parameters on the results is investigated in detail. The error of static electrical conductivity calculation is estimated to be about 20%; more accurate results require bigger number of atoms.

Electrical and optical properties of in and Al doped ZnO thin film

In this study, to improve the electrical and optical properties of aluminium (Al) doped zinc oxide thin films, we have added small amounts of indium (In) to Al doped ZnO thin films. We will present the results of In and Al doped ZnO thin film on glass substrates prepared by the sol-gel processing method. A rapid thermal annealing process was applied to cure the thin film properties. Different amounts of In were used to dope the AZO thin films to find the optimum process condition. The effects of crystallinity were analyzed by an x-ray diffraction method. In addition, the optical transmittance and electrical proprties of In doped AZO thin films were investigated.

Temperature dependence of optical properties of aluminum(III) meso-tetra(benzo-15-crown-5)porphyrinate solution in toluene

Aluminum(III) meso-tetra(benzo-15-crown-5)porphyrinate (AlClTCP) is produced from aluminum(III) chloride and meso-tetra(benzo-15-crown-5)porphyrin (H2TCP) in boiling pyridine. The structure of the novel compound was determined by electronic absorption spectroscopy, nuclear magnetic resonance, and MALDI TOF mass spectrometry. The color of the AlClTCP solution in toluene was found to depend on temperature, namely, the heated solution is pink, while the cooled one is green. Changes in the electronic absorption spectra and fluorescence spectra of the solution depending on temperature are analyzed. According to the data of dynamic light scattering, gradual cooling of the AlClTCP solution in toluene heated to 120°C results in the formation of nanoparticles with a mean diameter of several hundred nanometers that assume a spherical shape. The self-assembly is assumed to take place via the change from the monodentate coordination of the chloride anion by Al3+ cation in AlClTCP molecules to a bridgelike coordination.

Effect of annealing temperature on the optical and electrical properties of aluminum doped ZnO films

abstract Aluminum doped ZnO thin films were successfully deposited on the silicon substrates by spin coatingmethod. The effects of an annealing temperature on electrical and optical properties were investigatedfor 1.5 at.% of aluminum. Refractive index profile has been obtained for the film annealed at 350 C usingellipsometry and it has shown minimum refractive index of 1.95 and maximum value of 2.1. Thicknessprofile shows quite good uniformity of the film having minimum thickness value of 30.1 nm and maxi-mum value of 34.5 nm. Maximum conductivity value obtained was 4.63 X 1 -cm 1 for the film annealedat 350 3C. Maximum carrier density of 2.20 10 17 cm was deduced from the Hall measurement andFourier transform infrared spectroscopy clearly reveals major peak at 407 cm 1 in the spectra associatedwith the ZnO bond. 2009 Elsevier B.V. All rights reserved. 1. IntroductionTransparent conducting oxide (TCO) films are of prominentinterest due to their potential in optoelectronic devices such astouch panels, flat panel displays (FPD), and thin film solar cells[1,2]. For display applications, TCO films of high optical transmit-tance in the visible region and high electrical conductivity are re-quired. Indium tin oxide (ITO) has been commercially used forthe flat panel displays [3,4]. However, impurity-doped zinc oxides(ZnOs) serves as an alternative for ITO-based TCO because of itsadvantages of low cost, resource availability and nontoxicity. Zincoxide is accepted as wide band gap semiconductors as an alterna-tive to GaN because it has band gap of 3.37 eV at room tempera-ture, large free exciton binding energy (60 meV), and highmechanical and thermal stabilities. With enhancement in the qual-ity andcontrolof conductivityinbulkZnO [5] foundits potentialasa material for short wavelength light emitters and transparentelectronics [6,7].Generally, the undoped ZnO is showing a n-type conductivity.Particularly, an Al doped ZnO transparent conductive oxide (TCO)filmhashightransmittanceinthevisibleregionwithalowresistiv-ity and by doping it with aluminum its electrical properties can beimproved[8,9].Asaresult,theAldopedZnOshowsexcellenttrans-parency over the entire visible spectrum and has better transportproperties than tin oxide due to higher electron mobility. Thereare several methods used for the fabrication of ZnO thin films suchas pulsed laser deposition [10–12], sputtering [13,14], molecularbeam epitaxy [15], and sol–gel process [16], etc. Among thesemethods, the sol–gel technique has several advantages over theothers such as low cost, simplicity; homogeneity and large areafilms can be prepared at lower temperature.Many factors can affect the properties of aluminum doped ZnOfilms prepared by sol–gel method. Among them, Aluminum com-position and annealing temperature have significant effect on theoptical and electrical properties of the film. Present work reportsaluminum-doped zinc oxide films deposited on silicon substrateusing sol–gel spin coating process. We have already reported effectof aluminum doping on the properties of the films [9]. Here, wehave investigated effect of annealing temperature on the Alumi-num doped ZnO films prepared by sol–gel method on the siliconsubstrate by considering 1.5 at.% of aluminum. The main goal ofthe paper is to investigate effect of annealing temperature on theelectrical and optical properties of the aluminum doped ZnO filmsby keeping aluminum concentration fixed.

Synthesis and optical properties of aluminum and zinc quinolates through styryl subsituent in 2-position

4-Methyl(methoxy or chloro)benzaldehyde reacted with 2-methyl-8-quinolinol to afford the corresponding substituted 2-styryl-8-quinolinol. The latter was used as chelating ligand to prepare aluminum and zinc complexes. The spectroscopic, thermal, thermomechanical and optical properties of these complexes were investigated. The thermal stability of the complexes was much higher than the reference complexes AlQ 3 and ZnQ 2. The char yield at 800 °C in N 2 for typical complexes of Al and Zn was 49–64% whereas that for the reference complexes was 13–31%. The processability of the complexes was improved since they were soluble in common organic solvents such as THF, chloroform and acetonitrile. Solutions of complexes in THF emitted blue-green light with photoluminescence (PL) maximum at 513–576 nm that is considerably red-shifted relative to AlQ 3 (514 nm) and ZnQ 2 (535 nm). In addition, the PL maximum in THF of the synthesized Zn complexes was red-shifted as compared to the corresponding Al complexes. The nature of the styryl substituent (methyl, methoxy or chloro) of the chelating ligand influenced also the location of the PL maximum.

Optical Properties of Aluminium and Nitrogen in Compensated 4H-SiC Epitaxial Layers

ABSTRACTCompensating impurities affect the device performance but still the fundamental knowledge of this effect in SiC is poor. We demonstrate that the optical properties are affected by compensation effects between the nitrogen donor and aluminium acceptor in 4HSiC epilayers. As demonstrated using low-temperature photoluminescence measurements, the interaction occurs between the impurity bound excitons caused by changes in the aluminium concentration while the nitrogen concentration is constant. The variation is observed over two orders of magnitude in the aluminium concentration. The interplay is also observed in cathodoluminescence measurements between the band edge luminescence and nitrogen-aluminium donor-acceptor pair emission. These observations may be possible to utilize for a non-destructive characterization of compensated epilayers.

Grazing-incidence X-ray diffraction study of all-sputtered Al/CdS and CdS/Al interfaces

Optical properties of aluminum and cadmium sulfide are investigated at the CuKα wavelength in order to compute the penetration depth versus the angle of incidence. Grazing-incidence X-ray diffraction (GIXD) measurements are used to analyze the structural properties of all-sputtered Al/CdS and CdS/Al interfaces. The results show the existence of a 50 to 80 Å thick microcrystalline layer CdS is deposited on Al. When deposited on CdS. Al is implanted at a depth which is estimated around 150 Å.

Influence of the optical constants on Fabry-Perot coatings characteristics in the vacuum ultraviolet wavelength range

The influence of optical properties of aluminium and magnesium fluoride used as thin films on Fabry-Perot characteristics is studied in the 120-220 nm wavelength range. Reflectance and transmittance of double-layered coatings have been computed using combinations of different optical values. Comparison is made with measured values of reflectance.

Calculation of optical spectra of aluminum

The electronic structure and optical properties of aluminum were studied using the augmented-plane-wave (APW) method. To improve the agreement between the calculated electronic structure and experiment a semiempirical scheme of Chen and Segall was used to adjust the band structure. This parametrization was implemented by employing a few pieces of experimental data on de Haas-van Alphen cross sections, the position of a major optical peak and the bandwidth of A1. The parametrized bands and wave functions were used in a calculation of the dielectric constant of A1 in which the dipole matrix elements were included. The spectrum was analyzed with regard to the origin of structure in $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}$ space, with major structures treated analytically using the pseudopotential model. A novel aspect of this work is the elucidation of small-frequency behavior of the imaginary part of the dielectric constant which was shown to be nonzero at low frequencies due to an accidental degeneracy (in the absence of spin-orbit splitting) of the bands on the $\ensuremath{\Gamma}\mathrm{KWX}$ plane. The calculated spectrum is in very good agreement with optical data with respect to the location, strength, and width of major structures. A comparison between momentum matrix elements calculated by the pseudopotential and APW method is presented.

Ionoluminescence of Al, Cu, and Mo: Optical properties of aluminum

Impact of 10- to 30-keV ${\mathrm{H}}^{+}$ and ${\mathrm{He}}^{+}$ ions on polycrystalline Al, Cu, and Mo targets induces broad-band light emissions in the photon energy range of 2-6 eV; these emissions emanate from the target. For aluminum the emission is particularly intense, increases linearly with incident beam current, and is invariant in relative shape with projectile energy and angle of incidence. The dominant peak is at a photon energy of 2.4 eV; and a weak shoulder is observed at 3.3 eV. An electron-hole recombination model is shown to account for the general form of the emission band. We also calculate the electron density of states and the complex part of the dielectric constant ${\ensuremath{\epsilon}}_{2}$; the energy-band structure based on Ashcroft's Al pseudopotential is presented in tabular form.

Partial disorder in evaporated aluminium films

A simple model where it was assumed that the material near the grain boundaries constitute a disordered phase, has been used to explain the influence of deposition substrate temperature on the optical properties of aluminium.

Optical studies of the electronic structure of aluminium-manganese and aluminium-copper alloys

The authors have used the differential reflectance technique to study the changes in the optical properties of aluminium on alloying with small concentrations of manganese and copper. The measurements indicate that these impurities drastically modify the band structure of the pure metal. At concentrations of only a few atomic percent, the impurities so strongly scatter the aluminium conduction electrons that structure in the energy bands from Brillouin Zone boundaries is washed out, and the electrons in these alloys tend towards a free-electron response, though with short relaxation times. The data support Friedel's model of a rather wide impurity band of states, spanning the Fermi level in the manganese alloys but lying 5 eV below the Fermi level in the copper alloys.

Effect of Different Roughnesses on the Excitation by Photons of the Surface Plasmon of Aluminum

Different roughnesses induce changes of the interaction of incident light with surface-plasma oscillations. We observed those changes in the optical properties of aluminum. Identical aluminum films were deposited in ultrahigh vacuum (uhv) on substrates of varying roughnesses. We measured the reflectance at photon energies in the vicinity of the surface plasmon energy (1000–1600 A). We used overcoated substrates of different dielectrics (CaF2, MgF2, and LiF). In the terms of existing theories, we show that the curves are conveniently interpreted by taking into consideration (a) the light scattering by the surface characterized by the rms roughness σ and (b) the plasmon-photon interaction closely related to the roughness σand correlation length a. Thus, within the limit of accuracy (ΔR = ±0.5%) the roughness can be determined; σ is a function of the dielectric’s thickness with Δσ<0.5 A and the correlation length a (5 A<Δa<10 A) appears to be a characteristic of the nature of the dielectric. A study under an electron microscope confirms the theoretical strong value of roughnesses and shows the condensation process of aluminum on the rough substrates.