A systematic and detailed analysis of the influence of hydrogen (H2) dilution of silane (SiH4) on the structural properties of thin hydrogenated silicon (Si:H) films was carried out. The Si:H films were prepared by plasma enhanced chemical vapour deposition method at different H2 to SiH4 flow ratios (R) ranging from R¿=¿0 to 40. A detailed structural analysis was carried out by X-ray diffraction (XRD). In order to suppress the XRD intensity from the substrate, Si:H films were deposited onto a [100]-oriented single-crystalline silicon substrate and XRD was carried out with a thin-film attachment. The XRD analysis demonstrated that the first diffraction peak in the Si:H films corresponded to the signal from silicon hydride (Si4H) ordered domains having tetragonal lattice structure. The full width of half maximum (FWHM) of the peak was decreasing with increasing H2 dilution, and remained nearly constant for R¿¿¿20. The FWHM values confirmed that the Si:H films grown at R¿¿¿20 are more ordered than films deposited at lower R. This trend was confirmed by the Raman spectroscopy from the analysis of the shift of the Raman amorphous peak.@en

A systematic structural analysis was carried out on amorphous silicon films prepared from hydrogen-diluted silane using plasma-enhanced chemical vapor deposition. Hydrogen dilution of silane during the growth of a-Si:H absorber layers is used to suppress light-induced degradation of a-Si:H solar cells. Transmission electron microscopy (TEM) shows that for higher hydrogen dilution ratios the growth of films becomes strongly inhomogeneous and the transition from amorphous to microcrystalline phase occurs at a smaller thickness. A detailed X-ray diffraction (XRD) analysis of the amorphous films reveals that the strongest peak in the XRD patterns is located around 27.5° and corresponds to the signal from the ordered domains of tetragonal silicon hydride and not from cubic silicon crystallites. The full width at half maximum of this peak narrows from 5.1° to 4.8° as the ratio of hydrogen to silane flow (R) increases to 20 and does not change significantly for higher hydrogen dilutions. The presence of silicon hydride ordered domains in amorphous films is confirmed by the lattice imaging method applied to the high resolution TEM recordings. The amorphous silicon films fabricated at different hydrogen dilution were applied as absorber layers in single-junction solar cells. The degradation experiment confirms that the cells with absorber layers deposited using hydrogen dilution are more stable to light exposure. A clear reduction of the degradation is observed when the dilution ratio is increased from R = 0 to R = 20. The degradation of solar cells with absorber layers prepared at R > 20 is not reduced by further increasing R.@en

X-ray diffraction (XRD) analysis of thin silicon films was carried out using both the symmetric Bragg-Brentano and asymmetric thin-film attachment geometries. The asymmetric configuration allows quantitative phase analysis of the films and reveals that amorphous silicon films deposited from silane diluted with hydrogen have the strongest peak in the XRD patterns located around 27.5 degrees. This peak corresponds to the signal from ordered domains of tetragonal silicon hydride and not from cubic silicon crystallites. The full width at half maximum (FWHM) of this peak narrows from 5.1 to 4.8 degrees as the ratio of hydrogen to silane flow (R) increases to 20 and does not change significantly for higher hydrogen dilutions. The amorphous silicon films fabricated at different hydrogen dilution were applied as absorber layers in single-junction solar cells. Degradation experiments confirm a substantial reduction of the degradation when the dilution ratio is increased from R=0 to R=20. The light induced degradation of solar cells with absorber layers prepared at R > 20 is not further reduced by increasing R.@en