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International audienceHydrogenated nanocrystalline silicon carbide were grown at various deposition temperatures T-d from 200 to 600 degrees C by means of reactive magnetron sputtering in a plasma of 80% H-2 and 20% Ar mixture. A detailed investigation of the structural, compositional, phase nature, and morphology was carried out by complementary sophisticated techniques, such as Fourier transform infrared spectroscopy, x-ray diffraction (XRD), Rutherford backscattering, nuclear reaction, and elastic recoil detection analysis techniques, in addition to conventional and high-resolution transmission electron microscopy (HRTEM) observations. A crystallization onset with a fraction of 35% was observed for T-d=300 degrees C, which improved to 80% for T-d=600 degrees C, reflected by an increasing density of the SiC nanocrystals which kept an average size of about 5 nm. The observed fiber textures present < 102 > and < 11...> texture components, with ... larger than 2, while SiC nanocrystals elongated along the [111] direction are also evidenced. These latter are supported by the careful analyses of the HRTEM images which show evidence of faulted growing cubic SiC, as the origin of the very close hexagonal 6H-SiC structure taken into account in the XRD refinement. These various features were found quite consistent with the optical properties of the layers, and, in particular, the evolutions of both optical gap and static refractive index

A high effi ciency infrared quantum cutting effect in a Tb 3+ -Yb 3+ codoped silicon oxynitride system is demonstrated. The thin fi lms are deposited on Si substrates by reactive magnetron co-sputtering of a Si target topped with Tb 4 O 7 and Yb 2 O 3 chips under pure nitrogen plasma. The photoluminescence dynamics are investigated, revealing a quantum effi ciency of this system at 980 nm up to 197% for the higher Yb 3+ concentration. Thus, via a cooperative transfer mechanism between Tb 3+ and Yb 3+ , an absorbed UV-visible photon gives rise to almost two emitted IR photons. Such a down-conversion effect is demonstrated upon indirect excitation of energy donors, via defect states in the host matrix. These down-converter fi lms could be directly and easily integrated on top of the Si-based solar cell to improve the photoelectric conversion effi ciency at a lower cost. An evaluation of the additional external quantum effi ciency is deduced from this optical system and found to be almost 2%.Adv. Optical Mater. 2013, 1, 855-862 856 wileyonlinelibrary.com