Luminescent Properties of Glasses Based on Lithium Tetraborate Doped with Sm3+ and Gd3+

Glass Physics and Chemistry - Glasses based on lithium tetraborate obtained by solid-phase synthesis and doped with earth elements Sm3 +, Gd3 + have been investigated. The absorption and...     

The efficacy of recombinant vaccines against hepatitis B and the results of their use in a schedule for pediatric prophylactic inoculations

The results of field clinical trials of Russian and American yeast vaccines against hepatitis B are presented. The study revealed that both vaccines were faintly reactogenic, safe and exhibited high immunological activity. After the full course of immunization following the schedule 0-1-2 months 92.5% and 97.5% of patients receiving, respectively. Russian vaccine "Combiotech" and American vaccine "H-B-Vax II" were found to have specific antibodies. The maximum effect was registered when the vaccines were introduced according to the schedule 0-1-6 months. Seroconversions were observed in 97.5% and 100% of the vaccinees receiving the Russian and American vaccines respectively, in the latter case the highest antibody level being observed. The use of the vaccines within the prophylactic immunization schedule showed that antibodies to hepatitis B appeared in immunized children in 93-100% of cases. Seroconversion indices and the levels of antibodies to diphtheria, tetanus, poliomyelitis and measles were statistically significant and were the same in children receiving only the vaccines according to the immunization schedule and in children immunized, in addition to these vaccines, against hepatitis B.     

An investigation of certain regularities of oxygen-flash smelting of copper sulfide concentrates using computer simulation

Dependences of temperature of the products of oxygen-flash smelting of copper sulfide charge on the furnace capacity, copper content in the charge, oxygen content in the blast, and charge humidity are investigated. A mathematical model is suggested that was obtained by implementing the planned simulation experiment. Mass and heat balances are calculated using developed software. Independent variables are ranged by the force of their effect on the slag temperature. The strongest effects are exerted, first of all, by the copper content in the matte, followed by the amount of copper and sulfur in the charge.     

Texturized interface as a basis of surface-barrier heterostructure for solar cells application

Simulation of the photocurrent of surface-barrier structures (SBS) with texturized interface has been performed on the basis of obtained theoretical expression for internal quantum efficiency of homogeneous SBS and the model of parallelly connected diodes. The role of various sources of recombination losses (in the semiconductor, at the interface and due to the emission of majority carriers into the metal) in solar energy convertors has been analyzed. The complex method of characterization of SBS with texturized interface is proposed that includes an analysis of optical, electric and photoelectric characteristics. The possibility to increase the photosensitivity of the Au/GaAs SBS due to texturization and sulfur passivation of the interface for two types of microrelief (dendritic and quasigrating) obtained by wet anisotropic etching has been investigated. The morphology and statistical geometric characteristics of the interface were investigated by atomic force microscopy (AFM). The obtained results allowed to determine the change of optical and electronic (recombination) parameters of the interface caused by the used processing (texturization, passivation).     

Molybdenum disilicide interaction with barium borates glass in air

Translated from Poroshkovaya Metallurgiya, No. 3, pp. 67–71, March, 1992.     

Photovoltaic converters based on GaAs and AlGaAs epitaxial layers on GaAs substrates with developed surface area

MOCVD and LPE technologies of deposition of GaAs and AlGaAs layers onto (100) GaAs substrates with a developed surface area are developed. Porous GaAs layers and surface microprofiles of dendrite and quasi-grating types were fabricated on these substrates. The quality of layers was determined in comparative studies of the surface morphology and X-ray diffraction. Further, photovoltaic converters based on these layers have been devised. The best parameters among the samples under study were attained in photovoltaic converters based on the layers with the dendrite-type microprofile of substrate, which had the most developed area of the working surface and the dislocation density of 10⁴ cm^?2. In particular, at the wavelength of 0.65 μm, the external quantum efficiency of these photovoltaic converters was 150% higher than in the reference samples produced on a smooth surface.     

Fluctuation model for p–n heterojunction solar cells

Influence of the roughness (microrelief) of an active interface in p–n junction solar cells (SC) on the photovoltage (the open-circuit voltage V_oc) has been studied. Nonuniformity of contact potential difference between p- and n-regions leads to barrier height fluctuation that are exponentially enhanced when dealing with barrier current. This results in some decrease of the V_oc value. Three theoretical models of averaging open-circuit voltage were used. Experimental results on p⁺-Al_xGa_1−xAs/p⁺-n-GaAs heterostructure SC with various microrelief, obtained by the anisotropic chemical etching, are compared with theoretical calculations.     

Analysis of thin film surface barrier solar cells with a microrelief interface

The influence of a microrelief interface between a thin conductive film (emitter) and a semiconductor substrate (absorber) on the optical and recombination losses in surface barrier solar cells is analyzed.Equations for the calculation of monochromatic light transmission through a thin absorbing film with one or two rough surfaces, on an absorbing substrate, are presented. For a weakly texturized interface and a normal direction of the incident light, the influence of the microroughness is taken into account by the formulae obtained. A model of patches with microsurfaces parallel to the structure surface and ones inclined to it at a certain angle (the most probable statistically) was used to describe the experimental results. Au/GaAs surface barrier structures with interface microrelief of a quasigrating or a dendritic type, obtained by chemical anisotropic etching of GaAs, were investigated. The geometric and statistical parameters of the microrelief were determined by atomic force microscopy techniques. The recombination parameters of the textured interfaces were determined from the experimental spectra of the external quantum efficiency, taking into consideration the calculated spectra of light transmittance. A comparison of the internal quantum efficiency spectra with the calculated ones allows a determination of the electronic parameters of the interface. Both the photoconversion parameters under AM0 simulated illumination and the tolerance for ⁶⁰Co γ-irradiation, obtained for structures with various interface microrelief morphologies, allowed identification of microrelief of the quasigrating type as more suitable for solar cell applications.