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Optical Engineering

Broadband absorptance enhancement of silicon nanowire arrays with germanium as the substrate
Author(s): Han Wang; Xin-Lin Xia
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Paper Abstract

A composite structure with silicon nanowire arrays on germanium substrate is proposed as a good candidate for highly efficient solar cells. The Bruggeman approximation considering anisotropic wave propagating in uniaxial media is employed to calculate the radiative properties. Meantime, finite-difference time-domain (FDTD) method is used to verify for both normal and oblique incidence. It is found that the composite structure has superior absorption characteristics over thin Si film, particularly near the bandgap. With a thickness only of 4 μm, the composite structure improved the absorptance to above 0.6 across the whole wavelength band with the lattice constant of 100 nm, and the ultimate efficiency about 10% is higher than that of infinite bulk silicon, owing to the combined effects of suppressed reflection and high light trapping capability. To better understand the absorption enhancement process in the composite structure, the photogeneration profiles are provided by using FDTD method.

Paper Details

Date Published: 8 August 2013
PDF: 7 pages
Opt. Eng. 52(8) 087104 doi: 10.1117/1.OE.52.8.087104
Published in: Optical Engineering Volume 52, Issue 8
Show Author Affiliations
Han Wang, Harbin Institute of Technology (China)
Xin-Lin Xia, Harbin Institute of Technology (China)

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