Boron‐doped hydrogenated silicon carbide alloys containing silicon nanocrystallites (p‐nc‐SiC:H) were prepared using a plasma‐enhanced chemical vapor deposition system with a mixture of CH 4 , SiH 4 , B 2 H 6 and H 2 gases. The influence of hydrogen dilution on the material properties of the p‐nc‐SiC:H films was investigated, and their roles as window layers in hydrogenated nanocrystalline silicon (nc‐Si:H) solar cells were examined. By increasing the R H (H 2 /SiH 4 ) ratio from 90 to 220, the Si―C bond density in the p‐nc‐SiC:H films increased from 5.20 × 10 19 to 7.07 × 10 19 /cm 3 , resulting in a significant increase of the bandgap from 2.09 to 2.23 eV in comparison with the bandgap of 1.95 eV for p‐nc‐Si:H films. For the films deposited at a high R H ratio, the Si nanocrystallites with a size of 3–15 nm were formed in the amorphous SiC:H matrix. The Si nanocrystallites played an important role in the enhancement of vertical charge transport in the p‐nc‐SiC:H films, which was verified by conductive atomic force microscopy measurements. When the p‐nc‐SiC:H films deposited at R H = 220 were applied in the nc‐Si:H solar cells, a high conversion efficiency of 8.26% (V oc = 0.53 V, J sc = 23.98 mA/cm 2 and FF = 0.65) was obtained compared to 6.36% (V oc = 0.44 V, J sc = 21.90 mA/cm 2 and FF = 0.66) of the solar cells with reference p‐nc‐Si:H films. Further enhancement in the cell performance was achieved using p‐nc‐SiC:H bilayers consisting of highly doped upper layers and low‐level doped bottom layers, which led to the increased conversion efficiency of 9.03%. Copyright © 2015 John Wiley & Sons, Ltd. Wide bandgap (E 04 = 2.23 eV) p‐nc‐SiC:H window layers with enhanced vertical charge transport were successfully prepared using plasma‐enhanced chemical vapor deposition under a high hydrogen dilution condition, which led to the formation of Si nanocrystallites in the amorphous SiC:H matrix. When applied to n‐i‐p nc‐Si:H solar cells, these films significantly enhanced cell performance due to low recombination at the p/i interfaces, decrease of the series resistance and low absorption loss at the short wavelengths.
Boron‐doped hydrogenated silicon carbide alloys containing silicon nanocrystallites for highly efficient nanocrystalline silicon thin‐film solar cells
Progress in photovoltaics ; 23 , 12
2015
Aufsatz (Zeitschrift)
Englisch
BKL: | 53.36 Energiedirektumwandler, elektrische Energiespeicher |
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