Silicon production in a fluidized bed reactor: Final report

Technical Report · Tue Apr 01 04:00:00 EST 1986

OSTI ID:7125562

Rohatgi, N K

Part of the development effort of the JPL in-house technology involved in the Flat-Plate Solar Array (FDSA) Project was the investigation of a low-cost process to produce semiconductor-grade silicon for terrestrial photovoltaic cell applications. The process selected was based on pyrolysis of silane in a fluidized-bed reactor (FBR). Following initial investigations involving 1- and 2-in. diameter reactors, a 6-in. diameter, engineering-scale FBR was constructed to establish reactor performance, mechanism of silicon deposition, product morphology, and product purity. The overall mass balance for all experiments indicates that more than 90% of the total silicon fed into the reactor is deposited on silicon seed particles and the remaining 10% becomes elutriated fines. Silicon production rates were demonstrated of 1.5 kg/h at 30% silane concentration and 3.5 kg/h at 80% silane concentration. The mechanism of silicon deposition is described by a six-path process: heterogeneous deposition, homogeneous decomposition, coalescence, coagulation, scavenging, and heterogeneous growth on fines. The bulk of the grown silicon layer appears to be made up of small diameter particles. This product morphology lends support to the concept of the scavenging of homogeneously nucleated silicon. Excellent purity of the silicon product was obtained from an FBR equipped with a quartz liner. The product silicon had metallic contaminants less than the detection limits of spark source mass spectroscopy (e.g., Fe less than or equal to 0.6 ppMa, Cr < 0.02 ppMa, Zn < 0.04 ppMa, Co less than or equal to 0.1 ppMa). Solar cells fabricated from this pure silicon product showed encouraging results and the data are described in this report.

• Research Organization: Jet Propulsion Lab., Pasadena, CA (USA)
• DOE Contract Number: AI01-85CE89008
• OSTI ID: 7125562
• Report Number(s): DOE/JPL-1012-123; JPL-PUB-86-17; ON: DE87005427
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
CHEMICAL REACTORS
DESIGN
DIRECT ENERGY CONVERTERS
ELEMENTS
EQUIPMENT
FLUIDIZED BEDS
HYDRIDES
HYDROGEN COMPOUNDS
IMPURITIES
MASS SPECTROSCOPY
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PERFORMANCE
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PRODUCTION
SEMIMETALS
SILANES
SILICON
SILICON COMPOUNDS
SILICON SOLAR CELLS
SOLAR CELLS
SOLAR EQUIPMENT
SPECTROSCOPY