(Color online) (a) Optical bandgap E 04 (corresponding to the energy for which the absorption coefficient is 104 cm−1), and (b) refractive index, at 632 nm, of silicon-carbon alloys deposited by sputtering Si/C composed targets, as a function of silicon concentration determined by RBS. The vertical dotted line indicates the composition adopted in this work, while the horizontal line indicates the desired refractive index.
(Color online) Integrated reflectance spectra for different types of carbon structures: (a) amorphous carbon (DLC, PLC, and ta-C), and (b) a-Si0.32C0.78:H alloy, compared with the reflectance of conventional SnO2 deposited by spray pyrolysis and uncoated polished silicon.
(Color online) Integrated reflectance spectra for PLC/MgF2 and ta-C/MgF2 double-layer antireflective coatings on silicon compared with a conventional ZnS/MgF2 double-layer. The reflectance for textured silicon is also shown for comparison.
(Color online) Current density vs voltage of an illuminated silicon solar cell with and without a double-layer PLC/MgF2 antireflective coating, with a thickness of 59 ± 3 and 98 ± 5 nm, respectively.
(Color online) Variation of the refractive index (at approximately 632 nm) of unhydrogenated amorphous carbon films (a-C) as a function of the sp3 concentration.
(Color online) Variation of the refractive index (at approximately 632 nm) of hydrogenated amorphous carbon films (a-C) as a function of the sp3 concentration.
(Color online) Improvement in the short-circuit current density for some antireflective films developed here (right column), compared with the expected improvement using the experimental reflectance spectra of Figs. 2 and 3, but considering the films to be 100% transparent and the internal quantum efficiency of the solar cells equal to 1 (left column). The “ideal theoretical limit” was calculated considering the reflectance equal to zero in the whole range of the wavelength.
(Color online) Absorption coefficient of different structures of amorphous carbon (PLC, DLC, and ta-C) and a silicon-carbon alloy as a function of the wavelength, compared with the AM1.5 solar irradiance spectrum.
(Color online) Increase in the short-circuit current of crystalline silicon solar cells due to the use of an antireflective coating of a carbon-based material, compared with a conventional SnO2 antireflective coating.
Deposition condition of the different forms of amorphous carbon films.
Optical properties of different carbon structure (DLC, PLC, and ta-C), a-SiC:H, SnO2, and MgF2.
Percentage increase in the short-circuit current density (ΔJ sc ) of a variety of combinations of carbon-based materials in the silicon solar cell, including single- and double-layer antireflective coatings on polished and on texturized silicon (Text). The data in the brackets represents the total increase in the short-circuit current density when the texturization is taken into account.
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