Design of input couplers for efficient silicon thin film solar absorbers.
Opt Express
; 20 Suppl 6: A997-1004, 2012 Nov 05.
Article
in En
| MEDLINE
| ID: mdl-23187677
ABSTRACT
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 Si(3)N(4) 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, SiO(2) or Si(3)N(4), or high-index material, Si. The periodic pattern exhibited tunable and pronounced absorption peaks that are identified 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/cm(2), 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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Type of study:
Prognostic_studies
Language:
En
Journal:
Opt Express
Journal subject:
OFTALMOLOGIA
Year:
2012
Document type:
Article
Affiliation country:
South Korea