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Title: High-aspect-ratio silicon-cell metallization technical status report. Final report

Two features of the silicon concentrator solar cell are addressed which affect output at high concentration levels. The first is the development of narrow but high electroplated grid lines with improved conductivity. The object is a reduction in cell series resistance without increase in shadowing. This goal is accomplished by electroplating through a thick photo resist mask to produce lines .7 mil wide by .7 mil high. Advance pulse plating techniques are combined with pure silver plating baths to produce a deposit conductivity equal to the bulk silver conductivity (a 1.5 to 2 X improvement over conventional silver plating). The second feature is a double diffused selectively textured front surface. This development employs a deep diffusion in the silicon under the grid lines. Only the non grid line open area is selectively texture etched removing the deep junction. This open textured area is then given a second shallow diffusion for optimum cell efficiency. This selective procedure maintains the original highly polished wafer surface under the grid lines so that high resolution narrow grid lines are possible. The double diffusion protects the junction from metal diffusion while enabling the optimum shallow junction in the illuminated regions. Combining these two features hasmore » produced a large area concentrator cells (8 cm/sup 2/) with peak efficiency above 16% and exhibiting a broad peak efficiency extending from 50 to 175 suns above 15%.« less
Publication Date:
OSTI Identifier:
5428704
Report Number(s):
SAND-81-7033
ON: DE82011687
DOE Contract Number:
AC04-76DP00789
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of document are illegible
Research Org:
Sandia National Labs., Albuquerque, NM (USA); Boeing Aerospace Co., Seattle, WA (USA)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; CONCENTRATOR SOLAR CELLS; ELECTRIC CONTACTS; ETCHING; GRIDS; SILICON SOLAR CELLS; SILVER; ELECTROPLATING; ASPECT RATIO; DESIGN; DIFFUSION; EFFICIENCY; ELECTRIC CONDUCTIVITY; HYDRAZINE; MASKING; OPTIMIZATION; ROUGHNESS; TEXTURE; DEPOSITION; DIRECT ENERGY CONVERTERS; ELECTRICAL EQUIPMENT; ELECTRICAL PROPERTIES; ELECTRODEPOSITION; ELECTRODES; ELECTROLYSIS; ELEMENTS; EQUIPMENT; LYSIS; METALS; NITROGEN COMPOUNDS; PHOTOELECTRIC CELLS; PHOTOVOLTAIC CELLS; PHYSICAL PROPERTIES; PLATING; SOLAR CELLS; SOLAR EQUIPMENT; SURFACE COATING; SURFACE FINISHING; SURFACE PROPERTIES; TRANSITION ELEMENTS 140501* -- Solar Energy Conversion-- Photovoltaic Conversion