GaAs and Al{sub 0.2}Ga{sub 0.8}As solar cells with an indirect-bandgap Al{sub 0.8}Ga{sub 0.2}As emitter -- Heterojunction cells

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:191137

Venkatasubramanian, R; Timmons, M L; Hutchby, J A ^[1]; Field, H; Emery, K ^[2]

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1. Research Triangle Inst., Research Triangle Park, NC (United States)
2. National Renewable Energy Lab., Golden, CO (United States)

In this work, the authors first present a high-performance p{sup +} Al{sub 0.8}Ga{sub 0.2}As-n GaAs heterojunction (HJ) cell, where the conventional p{sup +}GaAs emitter has been replaced by a p{sup +} Al{sub 0.8}Ga{sub 0.2}As hetero-emitter. The total thickness of the p{sup +} Al{sub 0.8}Ga{sub 0.2}As hetero-emitter is about 0.1 {micro}m, about twice that of window-layer thickness in conventional GaAs homojunction cells. The NREL-measured AM1.5G data on such a GaAs HJ cell include a V{sub oc} of the cell indicates no deleterious effect in placing the Al{sub 0.8}Ga{sub 0.2}As-GaAs hetero-interface in the depletion layer. Second, they describe a high-performance n{sup +} Al{sub 0.8}Ga{sub 0.2}As- Al{sub 0.8}Ga{sub 0.2}As HJ cell, where the conventional n{sup +} Al{sub 0.8}Ga{sub 0.2}As hetero-emitter. This HJ cell has helped them to obtain a significant and reproducible improvement in the cell performance (AM1.5, {eta} = 18.1%) over conventional Al{sub 0.8}Ga{sub 0.2}As HJ cell indicates a 42% improvement in J{sub sc}, a V{sub oc} increase of almost 110 mV, and an improved fill-factor, compared to homojunction cells. The improved J{sub sc} is a result of higher blue-response and an enhanced red-response. The saturation dark current density is not only lower in the HJ diodes but also consistent across the wafer, thus explaining both the higher V{sub oc} and the reproducibility of performance of the Al{sub 0.8}Ga{sub 0.2}As HJ cells.

• OSTI ID: 191137
• Report Number(s): CONF-941203--; ISBN 0-7803-1459-X
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
ALUMINIUM ARSENIDE SOLAR CELLS
ANTIREFLECTION COATINGS
CURRENT DENSITY
DESIGN
EFFICIENCY
ELECTRIC POTENTIAL
EXPERIMENTAL DATA
FILL FACTORS
GALLIUM ARSENIDE SOLAR CELLS
GERMANIUM
GOLD
MAGNESIUM FLUORIDES
MOLECULAR BEAM EPITAXY
NICKEL
PERFORMANCE
SPECTRAL RESPONSE
TITANIUM
VAPOR PHASE EPITAXY
ZINC SULFIDES