Graded-bandgap solar cells. Annual report, 1 September 1985-31 August 1986

Technical Report · Sat Sep 01 04:00:00 EDT 1984

OSTI ID:6239603

Olsen, L C

Graded-bandgap solar cells were investigated that have a structure consisting of an N-type graded emitter and a base region with a constant bandgap. The emitter bandgap was 2.1 eV at the front surface and then graded to 1.74 eV at the N/P homojunction based on a 1.74 eV bandgap. The aluminum gallium arsenide homojunction had a maximum value for internal photoresponse of 20% while the graded bandgap cell exhibited a peak value of 80%. Analyses of photoresponse data indicates the aluminum gallium arsenide homojunctions are characterized by minority carrier diffusion lengths of only .03 micrometers in the emitter and 0.1 micrometers in the base. Thus, the effective field resulting from the graded emitter in the graded-bandgap cell is necessary for an adequate photoresponse. Investigations of heteroface gallium arsenide solar cells continued with the purpose of building a data base for processing technology and characterization techniques. GaAs solar cells were fabricated with efficiencies over 17% using a P/N homojunction structure and AlGaAs heteroface. Electro-optical characterization of GaAs cells has resulted in improved understanding of minority-carrier properties, surface recombination velocity and current-loss mechanisms.

• Research Organization: Joint Center for Graduate Study, Richland, WA (USA)
• OSTI ID: 6239603
• Report Number(s): AD-A-179491/6/XAB
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
ALUMINIUM ARSENIDES
ALUMINIUM COMPOUNDS
ARSENIC COMPOUNDS
ARSENIDES
CHARGE CARRIERS
DIFFUSION
DIMENSIONS
DIRECT ENERGY CONVERTERS
ELECTRONIC EQUIPMENT
EQUIPMENT
GALLIUM ARSENIDE SOLAR CELLS
HOMOJUNCTIONS
JUNCTIONS
LENGTH
PHOTOELECTRIC CELLS
PHOTOSENSITIVITY
PHOTOVOLTAIC CELLS
PNICTIDES
POWER SUPPLIES
PROCESSING
SEMICONDUCTOR JUNCTIONS
SENSITIVITY
SOLAR CELLS
SOLAR EQUIPMENT
SPACECRAFT POWER SUPPLIES
SURFACES
VELOCITY