Phase 2, automated array assembly, Task IV, low-cost silicon solar array project. Quarterly report No. 3

Technical Report · Sat Jul 01 04:00:00 EDT 1978

DOI:https://doi.org/10.2172/6070913· OSTI ID:6070913

Functional 3-inch diameter reference cells were fabricated using conventional processes consisting of: POCL/sub 3/ diffusion, electroless nickel plating, solder dipping, and evaporated SiO AR coating. Both flash and texture-etched surface wafers were used. The flash-etched cells yielded output efficiencies of 10.3%, whereas the texture-etched cells were considerably lower. Other flash and texture-etched cells were processed by /sup 31/P ion implantation 25 keV and 3 x 10/sup 15/ ions/cm/sup 2/, thermal annealing, and electroless nickel plating, resulting in 7% AM1 efficiencies. Problems were experienced in the nickel plating process which contributed to poor ohmic contact adherence and the resulting low efficiencies. Laser annealing was performed by Quantronix with an Nd:YAG laser on our texture-etched, flash-etched, and polished ion implanted wafers. A programmed X-Y positioning stage was used for precise traversing across the wafer surface. Best results of 7.3% AM1 efficiencies were attained on .5 x .5 cm size cells with polished surfaces. These cells had evaporated Ti/Ag contacts but not sintered nor AR coated. I/sub sc/ of these small cells was 5 ma. This represents a 27 ma/cm/sup 2/ output based on active area only, and compares with 32 ma/cm/sup 2/ for a conventionally processed cell of 11% AM1 efficiency. A cost analysis was prepared which reflects potential cost savings of laser annealing over thermal annealing in excess of $35 million. This savings is due to a projected cell efficiency improvement of 2%, resulting in reduced quantities of cells for the 500 megawatt capability. Spraying of tantalum solutions was performed on 2 x 4 cm space cells using the Zicon Autocoater. Cells were electrically tested at the outset in the as-received condition with SiO AR coating.

• Research Organization: Lockheed Missiles and Space Co., Inc., Sunnyvale, CA (USA)
• Sponsoring Organization: USDOE
• OSTI ID: 6070913
• Report Number(s): DOE/JPL/954898-3
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
ANNEALING
COATINGS
CZOCHRALSKI METHOD
DEPOSITION
DIFFUSION COATING
DIRECT ENERGY CONVERTERS
FABRICATION
HEAT TREATMENTS
ION IMPLANTATION
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHOTOVOLTAIC POWER PLANTS
POWER PLANTS
SCREEN PRINTING
SILICON SOLAR CELLS
SOLAR CELL ARRAYS
SOLAR CELLS
SOLAR POWER PLANTS
SPRAYED COATINGS
SURFACE COATING