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In this article, details of the brake mechanism and the method of determining the concentration of metals in the particles formed from the wear of tires as a result of the movement of cars, as well as a comparative analysis of road dust formed on asphalt-concrete roads of different composition are covered. In cities’ traffic-related sources are a substantial source of particulate pollution. The following categories of traffic-related particles exist: brake mechanism details, formed as a result of tire wear and wear to the road surface, accumulate due to turbulence caused by traffic, and exhaust particles released as a result of incomplete combustion of fuel and volatilization of lubricants during combustion. The method of determining the metal concentration in the formed particles, data on the physical and chemical properties of the particles are presented. Information is given on the negative impact on human health of the particles formed as a result of wear of the details of the car brake mechanism.

The behavior of the trapping times of minority carriers in In-doped CdTe films because of annealing and hydrogenation was examined through photoconductivity (PC) measurements on as-grown, annealed, hydrogenated, and hydrogenated and annealed In-doped CdTe epitaxial films grown on p-CdTe (211) substrates by molecular beam epitaxy. Results of the PC decay curve revealed a slow component with a time constant of a few milliseconds and this behavior was related to the presence of deep travel levels corresponding to minority carriers. The trapping times of the minority carriers were substantially decreased by the hydrogenation treatment.

The p-type GaN epilayers are prepared by metalorganic chemical vapor deposition and subsequently implanted with Fe(super +) ions. The study confirms that the photoluminescence peak at 2.5 eV is a donor-Fe acceptor transition and the photoluminescence peak around 3.1 eV is a conduction band-Fe acceptor transition.

A new study investigates the effect of surface passivation on the photoelectrical and optical properties of undoped p-CdTe(100) by (NH4)2Sx treatment.

In this paper, we report a study on the optical and electrical properties of pure cotton fibers from chemically surface and morphology modified and coated with poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) polymer samples by the dip-coating method. The treated and coated fibers properties were characterized by using scanning electron microscopy (SEM), photoluminescence, and I-V characteristics. The performance of fibers with the MEH-PPV polymer as a coating component was investigated and an excellent white-light emission which consists of blue-, green-, and red-light-emitting bands was demonstrated. I-V characteristics of the sandwich-type devices consisting of successive layers of ITO-PEDOT-PSS- CF/MEH-PPV-Ag show that upon light illumination the current increases in both the forward and reverse bias conditions which suggest that the photoresponse parameters for the heterojunction are better than the composite alone. [ABSTRACT FROM AUTHOR]

Undoped and nitrogen doped ZnO films were deposited on Si substrates by ultrasonic spray pyrolysis at ambient atmosphere. The p type of conductivity for the nitrogen doped ZnO films has been observed. The concentration of free holes in ZnO films has been found to depend strongly on the resistivity of Si substrate. With decreasing of the substrate resistivity the concentration of free holes in ZnO films increases. The hole concentration of 1.1×1018 cm-3 and the hole mobility of 24 cm2 V-1 s-1 were observed in the ZnO films grown on the Si substrates with the resistivity of 0.001 Ω cm. [ABSTRACT FROM AUTHOR]

The study of diluted magnetic semiconductor based on GaN was performed employing a variety of various measurement techniques. p-type GaN epilayers were prepared by metalorganic chemical vapor deposition and were subsequently implanted with Mn[sup +] ions. The properties of Mn[sup +] ion-implanted GaN epilayers were investigated with optical and magnetic measurements. The results of photoluminescence (PL) measurement show that optical transitions related to Mn apparently appear at 2.5 and around 3.0 eV. It is confirmed that the PL peak at 2.5 eV is a donor-Mn acceptor transition and the PL peak around 3.0 eV is a conduction band-Mn acceptor transition. Ferromagnetic hysteresis loop was observed, and the temperature dependent-magnetization displayed a ferromagnetic behavior persisting up to ∼270 K. [ABSTRACT FROM AUTHOR]

Investigates the effects of the band-tail states on the exciton lines in unintentionally doped and Mg-doped GaN epilayers grown on sapphire substrates with the use of plasma-assisted molecular beam epitaxy. Relationship between the radiative recombinations of the carriers and the band-tail states.

A variety of various measurement techniques were employed to perform the study of diluted magnetic semiconductor based on GaN. The properties of Mn(super +1) ion-implanted GaN epilayers were investigated with optical and magnetic measurements.

The thermal diffusivity measurements have been used to study the magnetic phase transition in Zn0.95Mn0.05O doped by nitrogen. The critical parameters of the ferromagnetic-paramagnetic transition have been obtained through the analysis of the inverse of the thermal diffusivity near the Curie temperature. Taking into account that the inverse of the thermal diffusivity has the same critical behavior as the specific heat, the critical exponent α has been determined. The results are consistent with the three-dimensional Heisenberg model for the magnetic phase transition. [ABSTRACT FROM AUTHOR]

In this paper we report the results on the fabrication of diluted magnetic semiconductors Zn 1−x Mn x O 1−y S y thin films with manganese x = 0.05 and sulfur 0 ≤ y ≤ 0.15 compositions, respectively, by using ultrasonic spray pyrolysis method. The influence of the sulfur concentration on the band gap energy, structural and magnetic properties have been studied by using optical transmission, X-ray diffraction and superconducting quantum interference device (SQUID) measurements, respectively. The morphology and composition of samples were studied by using Scanning Electron Microscope (SEM) and X-ray photoelectron spectroscopy (XPS). With increasing of the sulfur concentration the band gap energy of composition decreases, while the magnetization increases proportional to the sulfur concentration. [ABSTRACT FROM AUTHOR]

p-type GaN epilayers were prepared by metalorganic chemical vapor deposition and subsequently implanted with Fe[sup +] ions. The properties of Fe[sup +] implanted GaN epilayers were investigated by various measurements. The results of photoluminescence measurement show that optical transitions related to Fe appear at 2.5 eV and around 3.1 eV. It was confirmed that the photoluminescence peak at 2.5 eV is a donor-Fe acceptor transition and the photoluminescence peak around 3.1 eV is a conduction band-Fe acceptor transition. Apparent ferromagnetic hysteresis loops measured at 10 and 300 K were observed, and the temperature-dependent magnetization displayed a ferromagnetic behavior persisting above 350 K. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Nowadays, oxide-based semiconducting nanostructures are widely regarded as one of the most essential elements of the modern semiconductor industry and for a number of advanced technological functions in electronics and optoelectronic platforms. In this regard, a CuO-based nanocomposite was synthesized through a facile surfactant-free wet chemical strategy, and its potential for photoelectronic applications has been demonstrated. The nature of the composite phase and its other structural characteristics were studied in detail using Raman and X-ray photoelectron spectroscopic tools. The particulate characteristics of the composite were inferred using transmission electron microscopic measurements. Room temperature luminescence measurements revealed that the optical activity of the composite spreads across the red and near-infrared region of the electromagnetic spectrum through corresponding transitions. The optoelectronic capabilities of the processed composite were investigated through fabricating a CuO composite/ZnO nanowire-based p–n heterostructure and studying its associated current–voltage (I–V) characteristics under photon illumination. The nature of charge carriers, flat band potential, charge transfer resistance and carrier density were also studied individually and collectively for each component comprising the heterostructure through Mott–Schottky and Nyquist type impedance plots. [ABSTRACT FROM AUTHOR]

The critical behavior of the ferromagnetic semiconductor Ga1-xMnxAs with different concentrations of Mn was experimentally studied by thermal diffusivity measurements in close vicinity of the Curie temperature. Because the inverse of the thermal diffusivity has the same critical behavior as the specific heat, this allowed us to determine the critical exponent α for the samples investigated. As the critical temperature was approached, the value of the critical exponent α, for most of the samples under investigation, showed a clear crossover from the mean-field-like to the Ising-like critical behavior. Investigation of this crossover behavior has enabled us to determine the values of the Ginzburg number and the exchange interaction length in Ga1-xMnxAs. [ABSTRACT FROM AUTHOR]

Optical and resistance switching properties in the Ag/ZnO/Pt structure were investigated. Two types of resistance switching (bipolar and monopolar) were observed. Photoluminescence measurements showed dissimilar emission spectra for the each type of switching that might be explained by different processes occurred during resistance switching. In case of the bipolar resistance switching, the change in the ultraviolet part of spectrum was observed and it was attributed to Ag+ ions migration. On the other hand, the monopolar switching demonstrated the changes in the visible luminescence emission that could be, in turn, interpreted by the generation/recovery of oxygen vacancies. [ABSTRACT FROM AUTHOR]

The specific heat measurement was used to study the magnetic phase transition in Zn0.95Mn0.05O. The magnetization dependencies on the magnetic field, M(H) curve, and on the temperature, M(T) curve measured by superconducting quantum interference device, indicate the ferromagnetic-paramagnetic phase transition in Zn0.95Mn0.05O doped by nitrogen has a Curie temperature of about 80 K. The temperature dependence of the specific heat reveals a pronounced λ shaped peak at 75 K for the nitrogen-doped sample. Such dependencies indicate a well defined second-order phase transition in this sample. [ABSTRACT FROM AUTHOR]

Zinc-blende-structured MnAs epitaxial films were grown on GaAs (100) substrates with InAs buffer layer. The resistivity and the Hall resistance behavior at various temperatures indicate that the MnAs thin film is half-metallic in nature. A MnAs/GaAs/MnAs spin-valve structure, fabricated utilizing half-metallic MnAs thin films, exhibited giant magnetoresistance properties. The ability to fabricate epirelated half-metallic films on semiconductor surface can facilitate construction of many spin valves and related devices for potential spintronics and magnetic memory applications. [ABSTRACT FROM AUTHOR]

We study properties of the line at 3.33 eV observed in photoluminescence (PL) emission spectra of various ZnO films prepared using pulsed laser deposition method. The influence of deposition parameters, such as oxygen pressure, laser fluence, post-annealing, and electric field exposure on intensity of this luminescence band has been investigated. The recombination characteristics are probed by temperature and excitation dependent PL spectroscopy. The obtained experimental data suggest that the 3.33 eV luminescence line in ZnO depends strongly on surface band bending and originates from recombination of bound excitons (BEs) complex located near the surface and grain boundaries. The anomalously small thermal activation energy of BE in comparison with the localization energy is explained by decreasing of the interface barrier. Possible nature of defects that bind free excitons and cause the 3.33 eV emission line in ZnO is proposed. [ABSTRACT FROM AUTHOR]

We have investigated the effect of additional doping by Be on the properties of Ga[SUB1-x]Mn[SUBx]As(x=50.03). For this relatively low value of x, the Curie temperature is observed to increase with increasing Be concentration. We show that the temperature dependence of the resistivity at zero magnetic field, including the resistivity maximum near the Curie temperature, can be successfully described by the magnetoimpurity scattering model proposed by Nagaev [Phys. Rep. 346, 387 (2001)] in both the paramagnetic and the ferromagnetic temperature regions. Quantitative analysis of the data in terms of this model yields the value of the p-d exchange energy &bar;N[SUB0β&bar;≈1.6eV for Ga[SUB0.97]Mn[0.03]As. [ABSTRACT FROM AUTHOR]

The p-type GaN epilayers were prepared by metalorganic chemical vapor deposition and subsequently Mn[sup +] ions implanted. The properties of Mn[sup +] ions-implanted GaN epilayers were investigated by optical and magnetic measurements. The results of photoluminescence measurement show that optical transitions related to Mn apparently appear at 2.5 eV and around 3.0 eV. It is confirmed that the photoluminescence peak at 2.5 eV is a donor-Mn acceptor transition. Ferromagnetic hysteresis loop was observed, and the temperature-dependent magnetization displayed a ferromagnetic behavior persisting up to ∼270 K. [ABSTRACT FROM AUTHOR]

GaN epilayers grown by molecular beam epitaxy were photoelectrochemically (PEC) oxidized in an aqueous KOH solution. The oxidation effect was investigated by defect-related photoconductivity and photoluminescence. The PEC treated GaN show decreased extrinsic photoresponse and concentration of deep level states in comparison with the as-grown sample. The PEC process also results in enhanced donor-bound exciton photoluminescence at 3.47 eV and restrained 3.4 eV band. No strain is detected in the PEC oxidized GaN. The 3.4 eV band is related to structural defects instead of oxygen impurities. Rather, the defects can be passivated by the PEC oxidation. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]