Title :
Lattice-mismatched GaAsP Solar Cells Grown on Silicon by OMVPE
Author :
Geisz, J.F. ; Olson, J.M. ; Romero, M.J. ; Jiang, C.-S. ; Norman, A.G.
Author_Institution :
Nat. Renewable Energy Lab., Golden, CO
Abstract :
We report on lattice-mismatched GaAs0.7P0.3 solar cells grown on silicon substrates. This composition of GaAs0.7P0.3 has a band gap of about 1.7 eV and is well suited as the top junction of a III-V/Si two-junction tandem solar cell. Using a thin, high-quality GaP nucleation layer, a lattice-matched GaN0.02P0.98 buffer layer, and a compositionally graded GaAsxP1-x buffer layer, the threading dislocation densities was reduced to less than 108 cm-2 in the active region. The efficiencies of these single-junction cells without any antireflection coatings were as high has 9.8% under the AM1.5G spectrum. The quality of these solar cells based on Voc is comparable to the best III-V solar cells ever grown on Si substrates with a III-V buffer
Keywords :
III-V semiconductors; MOCVD; buffer layers; dislocation density; energy gap; gallium arsenide; nucleation; solar cells; vapour phase epitaxial growth; GaAs0.7P0.3-Si; GaNPAs-GaP; GaP; III-V solar cells; OMVPE; Si; band gap; buffer layer; lattice-mismatched solar cells; nucleation layer; threading dislocation densities; top junction; two-junction tandem solar cell; Buffer layers; Epitaxial growth; Gallium arsenide; III-V semiconductor materials; Photovoltaic cells; Silicon; Substrates; Sun; US Government; Zinc;
Conference_Titel :
Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on
Conference_Location :
Waikoloa, HI
Print_ISBN :
1-4244-0017-1
Electronic_ISBN :
1-4244-0017-1
DOI :
10.1109/WCPEC.2006.279570
