Light-trapping optimization in wet-etched silicon photonic crystal solar cells

Journal Article · Tue Jul 14 04:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4926548· OSTI ID:22489519

Eyderman, Sergey ^[1]; John, Sajeev ^[1]; Hafez, M.; Al-Ameer, S. S.; Al-Harby, T. S.; Al-Hadeethi, Y. ^[2]; Bouwes, D. M. ^[3]

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1. Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7 (Canada)
2. Department of Physics, King Abdul-Aziz University, Jeddah (Saudi Arabia)
3. iX-factory GmbH, Konrad Adenauer–Allee 11, 44263 Dortmund (Germany)

We demonstrate, by numerical solution of Maxwell's equations, near-perfect solar light-trapping and absorption over the 300–1100 nm wavelength band in silicon photonic crystal (PhC) architectures, amenable to fabrication by wet-etching and requiring less than 10 μm (equivalent bulk thickness) of crystalline silicon. These PhC's consist of square lattices of inverted pyramids with sides comprised of various (111) silicon facets and pyramid center-to-center spacing in the range of 1.3–2.5 μm. For a wet-etched slab with overall height H = 10 μm and lattice constant a = 2.5 μm, we find a maximum achievable photo-current density (MAPD) of 42.5 mA/cm{sup 2}, falling not far from 43.5 mA/cm{sup 2}, corresponding to 100% solar absorption in the range of 300–1100 nm. We also demonstrate a MAPD of 37.8 mA/cm{sup 2} for a thinner silicon PhC slab of overall height H = 5 μm and lattice constant a = 1.9 μm. When H is further reduced to 3 μm, the optimal lattice constant for inverted pyramids reduces to a = 1.3 μm and provides the MAPD of 35.5 mA/cm{sup 2}. These wet-etched structures require more than double the volume of silicon, in comparison to the overall mathematically optimum PhC structure (consisting of slanted conical pores), to achieve the same degree of solar absorption. It is suggested these 3–10 μm thick structures are valuable alternatives to currently utilized 300 μm-thick textured solar cells and are suitable for large-scale fabrication by wet-etching.

• OSTI ID: 22489519
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 2 Vol. 118; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION
CRYSTALS
CURRENT DENSITY
ETCHING
FABRICATION
NUMERICAL SOLUTION
OPTIMIZATION
SILICON
SOLAR CELLS
TETRAGONAL LATTICES
TRAPPING
VISIBLE RADIATION
WAVELENGTHS