Sequential purification and crystal growth for the production of low cost silicon substrates. Annual report, 15 September 1979-14 September 1980
The objective of this program is to identify and develop low cost processing for fabricating large grain size polycrystalline silicon substrates. Metallurgical grade silicon (MG-Si) which is low cost and abundant for industrial usage was chosen as starting material. However, MG-Si cannot be used directly as substrates for solar cell fabrication for the following reasons: (1) it contains 1 to 2% metallic impurities, and (2) it is produced as irregular shapes with a fine grain structure. Various purification techniques have been reported. The techniques being studied under this program use direct methods for the purification of MG-Si. The process uses sequential steps of purification followed by crystal growth. The steps of sequential purification include: (1) leaching of MG-Si charge, (2) phase separation of non-soluble impurities from molten silicon, (3) reactive gas treatment of molten silicon, (4) liquid-liquid extraction (called slagging), and (5) impurity redistribution using ingot pulling. All the purification steps, with the exception of step (1), are performed in a consecutive manner using a crystal puller. The purified ingots will be produced in a desired ingot dimension and further recrystallization is not necessary. The theory and experimental results for each purification technique are presented. The relative effectiveness of the various steps are assessed and the most important step(s) are recommended. Finally the electrical characteristics of solar cells built on a thin epitaxial layer deposited on single pulled MG-Si substrates are discussed and compared to single crystal substrates. (WHK)
- Research Organization:
- Motorola, Inc., Phoenix, AZ (USA). Semiconductor Group
- Sponsoring Organization:
- USDOE, Office of Solar Energy
- DOE Contract Number:
- AC02-77CH00178
- OSTI ID:
- 6602302
- Report Number(s):
- DOE/SERI-8119-3/4
- Country of Publication:
- United States
- Language:
- English
Similar Records
Sequential purification and crystal growth for the production of low cost silicon substrates. Quarterly technical progress report No. 1, 15 September 1979-31 December 1979
Sequential purification and crystal growth for the production of low cost silicon substrates. Final technical report, September 15, 1979-January 1, 1982
Related Subjects
36 MATERIALS SCIENCE
SILICON
CRYSTAL GROWTH
PURIFICATION
SILICON SOLAR CELLS
FABRICATION
ELECTRICAL PROPERTIES
IMPURITIES
LEACHING
PERFORMANCE
POLYCRYSTALS
PRODUCTION
RECOMMENDATIONS
SUBSTRATES
CRYSTALS
DIRECT ENERGY CONVERTERS
DISSOLUTION
ELEMENTS
EQUIPMENT
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
SEMIMETALS
SEPARATION PROCESSES
SOLAR CELLS
SOLAR EQUIPMENT
purification
crystal growth
production
silicon
substrates
polycrystals
impurities
leaching
silicon solar cells
electrical properties
fabrication
performance
recommendations
140501* - Solar Energy Conversion- Photovoltaic Conversion
360601 - Other Materials- Preparation & Manufacture