The Chlorine FREE Technology of producing Solar GRADE Silicon
The technology is used for production of polycrystalline silicon of high quality for photovoltaic industry and in the semiconductor electronics.
Chlorine-free technology of polycrystalline silicon production
Initial components: ethanol and metallurgical silicon
Si + 3 C2H5OHSiH (OC2H5)3
4SiH (OC2H5)3 SiH4 + 3 Si(OC2H5)4
SiH4 Si + 2H2
As a result of realization of technology:
n Cost of polycrystalline silicon is reduced in2times up to 15dollars / kg.
n Cleanliness and quality of silicon is increased in 10 times up to 99,999 %
n Manufacture becomes ecologically safe
Some techno-economic statistics
Basic material (metallurgical silicon) containing 1—3% ballast content and ethanol are available in unlimited quantaties at a low price.
Advantages of this technology:
— you dont use chlorine compound, that is why the whole process is ecologically safe, all procedures are carried out under a normal pressure and temperature not higher than 300Ñ;
— chemical reactions are connected only with silicon and are carried out almost without transfer of secondary impurities, this brings down the price of refining;
— reactionary products dont interreact with the reactor walls, minimizing the contamination of the final products;
— energy expenditure is about 30 kWh in comparisson with the usual method, when energy expenditure is about 200 kWh, this brings down the price twofold.
The basic product is monosilane and polycrystalline silicon of high purity.
The high quality of monosilane and polycrystalline silicon are proved by measured data. Specific resistivity of crystal samples is more than 10 000 ohm sm, and the time of life of minority carriers is about 1000 MS.
The technology allows to change the quantity and the range of the produced goods:
Polycrystalline silicon for electronic industry;
Polycrystalline silicon for photovoltaic industry;
Polycrystalline silicon for infrared photodevice and detectors of nuclear particles;
monosilane of high quality and its mixture with hydrogen and argon;
silicon dioxide of high purity;
and some others.