Persons

The problems in production of polycrystalline silicon for solar cells at present and in the nearest future have been considered. New progressive technologies, already realized in the pilot-scale production, as well as the recent original developments have been presented. In particular, the reduction of silicon oxides in the gas phase is a very promising process for production of high-purity silicon.

• Counter: 252 | Comments : 0

The changes in the structure and phase composition of silicon monoxide in the disproportional reaction at high temperature with the formation of the Si nanocrystalline phase have been investigated. The nanocrystalline powder after separation from silicon oxide by powder diffraction and small-angle X-ray scattering has been studied. It has been found that under optimal conditions of the silicon monoxide heat treatment the obtained powder contains the nanosilicon particles of 17-20 nm size in the volume fraction of 40%.

• Counter: 1286 | Comments : 0

The technological process for the production of silicon nanopparticles from silicon monoxide, which permits to control the particle size in the 2-10 nm range, and the methods of nanosilicon coating for solar cells have been developed. It has been shown that the nanosilicon films are characterized by good anti-reflection and passivating properties and can be successfully used in the solar cell production technology.

• Counter: 1580 | Comments : 0

At present the heteroepitaxial structures based on gallium arsenide and its solid solutions are the basis for manufacturing of solid state electronics devices. The main method of growing heteroepitaxial structures is the chemical deposition from vapors of metalorganic compounds and volatile hydrides. The electrically active impurities, uncontrollably coming into layers during the growing process, worsen the characteristics of the devices based on the heteroepitaxial structures. In this study a comparison of trimethylgallium (TMG) methods of synthesis into the synthesized product from the point of view of incoming of electrically active impurities in gallium arsenide (GaAs) has been carried out. As an object of the study, the methods of TMG obtaining, including the exchange reaction of gallium trichloride with trimethylaluminum (TMA), as well as the organomagnesium syntheses, with metallic magnesium used as an initial reagent, have been chosen. The behavior of the electrically active impurities during the purification of TMG by the rectification method has been studied. The studies have been performed by the methods of spectral analysis and functional control (based on the electrophysical parameters of GaAs epitaxial layers, grown from TMG and arsine. It has been found that the qualitative and quantitative composition of impurities in TMG after the synthesis (crude TMG) depends on their content in the initial reagents. TMG, obtained by the exchange reaction of gallium trichloride with TMA, is a source of the n-type impurities in GaAs. Basically it is an impurity of silicon. TMG, produced using metallic magnesium, is a source of impurities of both p -type (mainly zinc) and n -type (mainly silicon). Regardless of the quality of the crude TMG material, the use of the rectification method at reduced pressure makes it possible to obtain TMG with a low content of impurities. The GaAs epitaxial layers, grown using the purified trimethylgallium samples (TMG rectificate), have the n-type conductivity with a low background doping level ((0.7-4)×10 cm and high mobility of charge carriers - 7300-8500 cm/(V·s) at 300 K and 90 000-15 600 cm/(V·s) at 77 K. This corresponds to the purest samples of GaAs, grown by Metalorganic vapor phase epitaxy (MOVPE) technique using TMG and arsine. Based on the data of the functional control, the content of the impurities, exhibiting the electrical activity in GaAs in the obtained TMG rectificate samples is equal to the level of 10-10.

• Counter: 1835 | Comments : 0