Investigation of high-efficiency monolithic multibandgap solar cells. Final report, 15 Nov 88-14 Nov 90

Technical Report · Tue Jun 25 04:00:00 EDT 1991

OSTI ID:5208384

Olsen, L

This program concerned investigations of multibandgap solar cell structures with potential efficiencies greater than 40%. The basic concept utilized a monolithic stack of three or more cells based on Aluminum Gallium Arsenide and Indium Gallium Arsenide ternary compounds. In particular, the planned work for the two-year program was to involve research related to a three-cell stack comprised of a top Al.37Ga.63As cell, a middle Gallium arsenide cell and a bottom In.3Ga.7As cell. Efforts first concentrated on GaAs cell growth and fabrication, and then on AlGaAs film growth. Although significant progress was made in the development of AlGaAs film growth, efforts to grow InGaAs films and solar cells were not initiated. GaAs solar cells were fabricated from epi-wafers grown at WSU Tri-Cities. The cells had a p/n structure with Gold metallization and silicon monoxide anti-reflection coatings. Cells exhibited AM1.5 efficiencies greater than 21%. Studies of AlGaAs included development of procedures for growth of films of known aluminum concentration and measurement of minority carrier properties. The minority carrier diffusion length was found to be 0.6 micrometer for AlGaAs with a composition corresponding to 10% aluminum. Films with larger amounts of Al exhibited much lower values of diffusion length. Studies were conducted which determined that oxygen impurity levels in the AlGaAs were degrading minority carrier properties.

• Research Organization: Tri-Cities Univ. Center, Richland, WA (United States)
• OSTI ID: 5208384
• Report Number(s): AD-A-238718/1/XAB; CNN: AFOSR-89-0182
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
ALUMINIUM ARSENIDE SOLAR CELLS
ANTIREFLECTION COATINGS
ARSENIC COMPOUNDS
ARSENIDES
CHARGE CARRIERS
COATINGS
DESIGN
DIFFUSION
DIMENSIONS
DIRECT ENERGY CONVERTERS
EFFICIENCY
ELEMENTS
EQUIPMENT
FABRICATION
FILMS
GALLIUM ARSENIDE SOLAR CELLS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
GOLD
IMPURITIES
INDIUM ARSENIDES
INDIUM COMPOUNDS
LENGTH
METALS
NONMETALS
OXYGEN
PERFORMANCE
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PNICTIDES
SOLAR CELLS
SOLAR EQUIPMENT
TRANSITION ELEMENTS