Pulsed excimer laser processing for cost-effective solar cells. Quarterly report No. 1, May-July 1984

Technical Report · Sun Jan 01 00:00:00 EST 1984

DOI:https://doi.org/10.2172/6241179· OSTI ID:6241179

Wong, D.

The objective of this contract is to develop a solar cell process sequence that incorporates three process steps which use pulsed excimer lasers, to verify that this sequence yields high efficiency cells at a low cost, and to document the feasibility of carrying this technology from the laboratory bench scale to factory size. The three process steps are: junction formation, surface passivation, and front metallization. The effort is to take place during a one-year period. During this reporting period, a series of annealing experiments were conducted. Parameter variations included beam energy density, percentage of beam overlap, sources of diffusant, and different surface conditions such as chemical-mechanical polished, caustic etched, and textured. Diffusant deposition included spin-on liquid dopant and ion implant. Due to the lower surface reflectivity and the wetting effect by the spin-on source, textured wafers experienced more surface damage and stress than polished wafers. Maximum cell efficiency obtained for Cz polished wafers was 9% and for Cz textured wafers was 11.5% (no A/R). Surface damage limited the cell efficiency. Laser annealing on ion-implanted wafers was conducted with phosphorus implant with acceleration energy of 10 keV at fluences of 1-5 x 10/sup 15/ atom/cm/sup 2/. Maximum cell efficiency was less than 8% (no A/R coating). Low J/sub sc/, V/sub oc/, and fill factor suggested incomplete implant damage removal. Decreasing the implant voltage from 10 keV to 5 keV and increasing laser energy to above 0.9 J/cm/sup 2/, some cell efficiencies over 9.4% before A/R. The goal of producing cells of 16.5% has not materialized due to problems in ion implant uniformity, unavailable low keV ion implant, and laser beam inhomogeneity. During the next period, work will focus on developing a 1 keV glow discharge capability and on fabrication of Boron implanted junctions on n type wafers.

• Research Organization: ARCO Solar, Inc., Chatsworth, CA (USA)
• DOE Contract Number: NAS-7-100-956831
• OSTI ID: 6241179
• Report Number(s): DOE/JPL/956831-1; ON: DE85000468
• Resource Relation: Other Information: Portions are illegible in microfiche products. Original copy available until stock is exhausted
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
SILICON SOLAR CELLS
ANNEALING
FABRICATION
CRYSTAL DOPING
ECONOMIC ANALYSIS
EFFICIENCY
EXCIMER LASERS
ION IMPLANTATION
PERFORMANCE
DIRECT ENERGY CONVERTERS
ECONOMICS
EQUIPMENT
GAS LASERS
HEAT TREATMENTS
LASERS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
SOLAR CELLS
SOLAR EQUIPMENT
140501* - Solar Energy Conversion- Photovoltaic Conversion