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Energy Express

Energy Express

  • Editor: Christian Seassal
  • Vol. 20, Iss. S6 — Nov. 5, 2012
  • pp: A997–A1004

Design of input couplers for efficient silicon thin film solar absorbers

Sun-Kyung Kim, Kyung-Deok Song, and Hong-Gyu Park  »View Author Affiliations

Optics Express, Vol. 20, Issue S6, pp. A997-A1004 (2012)

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We investigated light absorption in various Si thin film solar absorbers and designed efficient input couplers using finite-difference time-domain simulation. In the simulation, a dielectric coating on Si thin film led to enhanced light absorption at near-ultraviolet to blue wavelengths, while the absorption peaks at longer wavelengths were nearly preserved. In a 300-nm-thick Si film with a 60-nm-thick Si3N4 top-coated layer, current density was augmented by ~35% compared to a bare Si film. For broadband absorption, we introduced two-dimensional square-lattice periodic patterns consisting of low-index dielectric materials, SiO2 or Si3N4, or high-index material, Si. The periodic pattern exhibited tunable and pronounced absorption peaks that are indentified as horizontally-propagating waveguide modes. The high absorption peaks were significantly amplified with increasing refractive index of the dielectric pattern. For a Si-patterned structure with a pitch size of 400 nm and a pattern depth of 80 nm, current density was achieved up to 17.0 mA/cm2, which is enhanced by a factor of 2.1 compared to the current density of bare Si film. Deep understanding of the light absorption in optical cavities with wavelength-scale thickness will be useful in the design of efficient thin film solar absorbers as well as novel nanophotonic elements.

© 2012 OSA

OCIS Codes
(050.0050) Diffraction and gratings : Diffraction and gratings
(350.6050) Other areas of optics : Solar energy
(070.7345) Fourier optics and signal processing : Wave propagation

ToC Category:

Original Manuscript: September 17, 2012
Revised Manuscript: October 21, 2012
Manuscript Accepted: October 23, 2012
Published: November 1, 2012

Sun-Kyung Kim, Kyung-Deok Song, and Hong-Gyu Park, "Design of input couplers for efficient silicon thin film solar absorbers," Opt. Express 20, A997-A1004 (2012)

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