Strebkov D. S., Zadde V. V., Kharchenko V. V.

The All-Russia Institute of the Electrification of an Agriculture.

Silicon, obtained as raw material is a subject to the subsequent processing by directional crystallization, by Cz-growth or casting method. These processes require significient energy expenses. Earlier [1,2] the opportunity of obtaining of silicon ingots in solar furnace with the structure and crystal perfection suitable for manufacturing solar cells with 10% efficiency was shown.

Parameters of obtained silicon.

Ingots of silicon in diameter of 40-50 mm were fabricated in focus of the solar furnace by a method of a floating zone without the special reactionary chamber directly in open air. Energy necessary for fusion of initial silicon energy was applied to a melted zone, formed on a butt — end face of seed rod in the form of the concentrated sunlight.

Ingots of silicon with SOG-Si parameters were obtained. They had a columnar structure with big graines extended along the growth axis and high values of diffusion length of minor carriers. In some cases up to 70 % of the brought up ingots had monocrystalline area. In monocrystal sites of ingots the density of the dislocations determined with etching pit technic use, made value from 10 up to 105cm-2 . The contents of oxygen determined by IR-absorption method despite of constant contact of a melting-pot bath of melt with atmospheric air, did not exceed value of 2.10 16 cm-3. Contents of impurities in the made samples of n and p-type correlated with their contents in initial raw material, however always had lower values.

And this fact concerned not only to the impurity having low segregation factor, but also to impurities which at solidification could be removed with difficulties (phosphorus), or practically could not be removed at all (boron).

In [3] it is shown, that at growing of silicon by the mentioned above method so intensive purification processes take place, that, in opinion of authors, the opportunity of SOG-Si production from metallurgical silicon as initial raw material becomes realistic.