Controlled Crystallinity of Silicon Powders

Silicon powder generated by the pyrolytic reaction of silane (SiH₄) in a free space reactor has been demonstrated to be produced in varying degrees of crystallinity depending on the temperature and other reactor conditions. The reactor is heated to no more than 650°C while flowing a feed gas comprising silane and a carrier gas into the reactor while maintaining an internal pressure of about 2 atm or less. The non-crystalline (amorphous) silicon is produced in a controlled composition with crystalline silicon. The crystallization composition of the powder is determined by a combination of Powder X-Ray Diffraction and Pair Distribution Function Analysis. Work to produce the silicon powder using a free space reactor was completed by the Institutt for energiteknikk (Kjeller, Norway) on research contract for Hemlock Semiconductor Corporation.