Alexander A. Berezin

Cuprous oxide–indium–tin oxide thin film photovoltaic cells

We studied thin films of cuprous oxide deposited on glass coated with transparent conducting indium–tin oxide (ITO) films. The deposition of both Cu2O and ITO was made by rf sputtering in an Ar/O2 gas mixture. For the deposition of Cu2O a pure copper target was used and ITO films were deposited from a disk target, the halves of which were made of Sn and In, respectively. This allows variation of the stoichiometry of the deposited ITO film by changing the position of the substrate glass beneath the Sn/In target. X‐ray diffraction of Cu2O films indicates the typical pattern of amorphous material. We were able to produce Cu2O films of different stoichiometry by varying the O2 to Ar ratio during rf sputtering. The maximum resistivity of the films corresponds to an ideal stoichiometry of Cu2O. An activation energy of 0.55 eV found from thermostimulated conductivity is related to excess Cu vacancies. The band gap found from the spectral dependence of the photovoltaic effect is 2.0 eV. The composition of ITO fil...

Formation of thin TiNxOy films by using a hollow cathode reactive DC sputtering system

TiNxOy films were deposited on glass by a reactive DC sputtering process, using a new hollow cathode with a cavity of 1.4 cm3. The discharge processes inside the cavity produces large densities of both sputtered and evaporated titanium particles and strongly affect the reactive processes for formation of titanium oxinitride film. The particles contributing to the film growth are ionized inside the cavity and ejected into the plasma chamber through a 5-mm nozzle, due to a pressure difference. The inner walls of the cavity were made of pure titanium. Pure argon was used as an operating gas, and a mixture of nitrogen and oxygen was added as a reactant gas (20% O2/80% N2). At an operating pressure of 0.05 torr (6.65 Pa), several samples with a thickness of a few microns were produced. Optical emission spectroscopy was used to examine the plasma parameters. The film’s structure was examined by X-ray diffraction methods showing the main peaks of (111), (200), and (220). Atomic force microscopy was used to investigate the surface morphology of the films. The samples were analyzed by energy dispersive X-ray spectroscopy and Auger electron spectroscopy, and a composition of Ti(40)N(20)O(40) was deduced. Measurements showed a microhardness of 1100 kp/mm2 and a surface roughness of 2.510 nm for this film.

Collection efficiency of ultrafine particles by an electrostatic precipitator under DC and pulse operating modes

High particle collection efficiency in terms of particle weight volume mg/m/sup 3/ is well achieved by a conventional electrostatic precipitator (ESP). However, the collection efficiencies in terms of number density for the ultrafine (particle size between 0.01 to 0.1 /spl mu/m) or submicron particles by a conventional ESP are still relatively low. Therefore, it is necessary to improve the collection efficiency for ultrafine particles. In this work, attempts have been made to improve the ultrafine particle collection efficiency using the short pulse energizations. The present version of ESP consists of three sets of wire plate type electrodes. For ESP under DC operation modes, experimental results show that the collection efficiency for DC applied voltage decreases with increasing dust loading when particle density is larger than 2.5/spl times/10/sup 10/ part/m/sup 3/. For ESP under pulse operating modes, the particle collection efficiency increases with increasing pulse peak voltage until 25 kV then decreases with increasing pulse peak voltage. The ultrafine particle collection efficiency based on particle density by DC energizations is much higher compared with pulse energizations without DC bias may be due to the reentrainments of ultrafine particles.

Mercury and other trace elements removal characteristics of DC and pulse energized electrostatic precipitator

Removal of zinc rich ash and mercury from gas stream using electrostatic precipitators has been investigated. Dust particles collected from Mastsuyama municipal incineration plant thermal plasma ash volume reduction system were used to study the performance of ESP to collect zinc rich ash. The ash was analyzed by neutron activation analysis (NAA) using the McMaster Nuclear Reactor. Collection efficiency as high as 99.9% was obtained in the removal of Zn from the flue gas with DC energization of the ESP. The mercury concentration was measured using a cold vapor atomic absorption spectrometer (CV-AAS) after sampling (OSHA-140 method) from the flue gas stream. As a function of concentration, the mercury collection efficiency was higher at higher concentration of mercury. Higher collection efficiency was obtained under negative DC energization compared to other modes of energization of the ESP; however, power consumption under pulse application was much smaller compared to DC energization.

Effects of the diversity of stable isotopes on properties of materials

Abstract We review some physical consequences of the basic premise that most crystalline solids are, in fact, random mixtures of stable isotopes. We place a special emphasis on the meaningful use of isotopic diversity and isotopic structuring for various applications in material science and engineering.

An isotopic disorder as a possible cause of the intrinsic electronic localization in some materials with narrow electronic bands

A new hypothesis relating the possibility of the existence of the intrinsic centers of electron (hole) localization in some crystalline materials with very narrow electronic (hole) bands is put forward. For the sake of definiteness, the discussion is based on the case of beta‐rhombohedral boron—the material with relatively large isotopic mass difference. We consider the supposition that the centers of intrinsic localization could result from Anderson electronic localization (AEL) induced by a random distribution of boron isotopes 10B and 11B among the regular sites of a complex unit cell. An estimation of the width of the narrow band required for the AEL is made in the frameworks of the one‐oscillator electron‐vibrational model. The obtained upper estimate for the width J≂0.3 meV seems to be a realistic one to provide the necessary order‐of‐magnitude for the AEL or, at least, to be comparable in strength with other possible sources of localization. This can be especially plausible in view of the possibili...

Semipilot plant pulse energized cold-precharger electrostatic precipitator tests for collection of moderately high resistivity flyash particles

The performance of an electrostatic precipitator (ESP) to collect moderately high resistivity flyash has been tested under pulse/precharger energization using the semipilot scale integrated electrostatics combustion flue gas (IECFG) cleaning system at Ontario Hydros 640 MJ/h Combustion Research Facility Center. The pulse energization enhanced the performance of the existing de-energized wire-plate electrostatic precipitator in collecting moderately high resistivity (/spl rho//spl sim/10/sup 10/ /spl Omega//spl middot/cm) flyash. A 26% improvement in particle collection efficiency and 30% energy saving were obtained with pulse energization, with moderately high resistivity flyash generated by burning high-sulfur (3.7%) Nova Scotia coal with limestone conditioning. The cold precharger specially designed to suit the three-stage wire-plate ESP has also been tested for its ability to improve the performance of ESP in reducing the back corona. With an additional 30% of energy supplied to the precharger it was possible to obtain up to 40% enhancement in collection efficiency. In general an enhancement factor of 1.8-2.8 was obtained with dust loading /spl sim/2 g/m/sup 3/. A thyratron switched pulse power supply was used for the ESP.

Atomization Characteristics of Electrohydrodynamic Limestone/Water Slurry Spray

Abstract The electrohydrodynamic atomization of limestone-water slurry was experimentally investigated. A double emission atomization mode is observed, which is similar to the fat configuration mode. With increasing the applied voltage, the droplet size and column length decrease, the spread angle, the droplet velocity and the droplet charge-to-mass ratio increase. Experimental results show that the volume-to-surface mean diameter has a minimum value and the droplet size distribution characteristics have two peaks.

Tin-doped In2O3 films deposited by r.f. sputtering

Abstract We studied tin-doped In 2 O 3 thin films deposited by r.f. sputtering2in an ArO 2 gas mixture. The subsequent heat annealing of the films increased their conductivity. The composition of the films was studied by Auger analysis. X-ray diffraction indicates structural changes during the annealing. The optical transmittance of the thin films was 80%–90% in the visible region for film thickness of 1500–2000 A.

Isotopic disorder as a limiting factor for the mobility of charge carriers

Abstract The effect of an isotopic disorder on the mobility of charge carriers in semiconductors is discussed. Weak isotopic variations of the site potentials are described in the model of the randomly placed scattering centers. The concentration of these weak scatterers is, however, very high (of the order of the total atomic concentrations) and, therefore, the additional scattering due to random locations of isotopes could lead to observable effects, especially at very low temperatures. The “ideal” (pure and defect-free) isotopically mixed crystalline silicon is considered as an example.