GaAs Solar Cells on Nanopatterned Si Substrates

Journal Article · Wed Oct 10 00:00:00 EDT 2018 · IEEE Journal of Photovoltaics

DOI:https://doi.org/10.1109/JPHOTOV.2018.2871423· OSTI ID:1480234

Warren, Emily L.  ^[1]; Jain, Nikhil ^[1]; Makoutz, Emily ^[1]; McMahon, William E. ^[1]; Tamboli, Adele C. ^[1]; Saenz, Theresa ^[1]; Vaisman, Michelle ^[2]; Li, Qiang ^[3]; Lau, Kei May ^[3]

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1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
2. Yale Univ., New Haven, CT (United States)
3. Hong Kong University of Science and Technology, Kowloon (Hong Kong)

Integrating III-Vs onto Si is a promising route toward tandem photovoltaics and cost mitigation of III-V substrates. While many III-V/Si photovoltaic integration approaches have been studied, epitaxial growth on Si allows for fewer processing steps compared to other approaches. However, current epitaxial pathways utilize expensive techniques, such as thermal cycle annealing or thick buffer layers to control defect densities, undermining the low-cost goal of integrating III-Vs with Si. Here, we present single-junction GaAs solar cells grown directly on Si using selective area growth as an alternative low-cost technique to control material quality with a much thinner buffer. We demonstrate a 10.4%-efficient GaAs device grown on a V-grooved Si substrate, which achieved an antiphase domain-free III-V/Si interface and a threading dislocation density of 2 x 107 cm-2, despite the lack of a graded buffer. We compare this growth on V-grooved Si to solar cells grown on polished Si with and without a patterned silica buffer layer, which demonstrate efficiencies of 6.5% and 6.8%, respectively; the polished Si was patterned using nanoimprint lithography, which is a low-cost patterning technique compatible with III-V selective area growth. Cracking is found to be a critical challenge that hinders solar cell performance and is exacerbated by the V-grooved Si surface topography. The results in this paper provide a promising pathway toward high-efficiency, low-cost III-V/Si tandem photovoltaics.

• Research Organization: National Renewable Energy Lab. (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1480234
• Report Number(s): NREL/JA-5900-71202
• Journal Information: IEEE Journal of Photovoltaics, Vol. 8, Issue 6; ISSN 2156-3381
• Publisher: IEEE
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
III-V/Si photovoltaics (PV) and solar cells
metalorganic chemical vapor deposition (MOCVD)
nanoimprint lithography (NIL)
selective area growth (SAG)