High-efficiency AlGaAs-GaAs solar cells with internal Bragg reflector

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:191149

Andreev, V M; Komin, V V; Kochnev, I V; Lantratov, V M; Shvarts, M Z ^[1]

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1. Russian Academy of Sciences, St. Petersburg (Russian Federation). A.F. Ioffe Physico-Technical Inst.

The work presents an investigation of solar cells (SCs) based on AlGaAs/GaAs heterostructures with internal Bragg reflectors grown by low-pressure MOCVD on n-GaAs substrates in a horizontal resistively heated reactor. The typical structure consists of: Bragg reflector (BR) having 12 periods, n-GaAs base layer with the thickness of 1,500--2,000 nm, 400--500 nm thick p-GaAs emitter, 70 nm thick p-AlGaAs passivating window and top p-GaAs contact layers. The BR with the reflectance maximum centered at the wavelength of 860 nm consists of twelve pairs of AlAs/GaAs layers. The resulting BR thicknesses is 71.6 nm for A.As and 59 nm for GaAs. In this case the peak of reflectance spectrum is in the area of 830--900 nm where the reflectance is close to unit. This multi-layer quasi-dielectric stack selectively reflect weakly absorbed photons with energies near the GaAs band gap for a second pass through the photoactive region increasing the photocurrent. The employment of the BR allows to increase the external quantum efficiency in the long wavelength range of the spectrum and to fabricate simultaneously a thinner n-GaAs base layer. The use of the internal BR, Ta{sub 2}O{sub 5} for antireflecting coating and prismatic cover allowed them to obtain efficiency of 23.4% (17.7 suns, AM0, 25 C) and 27.2% (23.4 suns, Am 1.5).

• OSTI ID: 191149
• Report Number(s): CONF-941203--; ISBN 0-7803-1459-X
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
ALUMINIUM ARSENIDE SOLAR CELLS
ALUMINIUM ARSENIDES
ANTIREFLECTION COATINGS
BRAGG REFLECTION
CHEMICAL VAPOR DEPOSITION
CURRENT DENSITY
DOPED MATERIALS
ELECTRIC CONTACTS
ELECTRIC POTENTIAL
FILL FACTORS
GALLIUM ARSENIDE SOLAR CELLS
GALLIUM ARSENIDES
MAGNESIUM
ORGANOMETALLIC COMPOUNDS
PERFORMANCE
QUANTUM EFFICIENCY
SCANNING ELECTRON MICROSCOPY
SILANES
TANTALUM OXIDES