Thermally induced solid-state reactions between a 70 nm Pt film and a single-crystal (001) β-SiC substrate at temperatures from 300 °C to 1000 °C for various time durations are investigated by 2 MeV He backscattering spectrometry, x-ray diffraction, secondary ion mass spectrometry, scanning electron microscopy, and cross-sectional transmission electron microscopy. Backscattering spectrometry shows that Pt reacts with SiC at 500 °C. The product phase identified by x-ray diffraction is Pt3Si. At 600–900 °C, the main reaction product is Pt2Si, but the depth distribution of the Pt atoms changes with annealing temperature. When the sample is annealed at 1000 °C, the surface morphology deteriorates with the formation of some dendrite-like hillocks; both Pt2Si and PtSi are detected by x-ray diffraction. Samples annealed at 500–900 °C have a double-layer structure with a silicide surface layer and a carbon-silicide mixed layer below in contact with the substrate. The SiC—Pt interaction is resolved at an atomic scale with high-resolution electron microscopy. It is found that the grains of the sputtered Pt film first align themselves preferentially along an orientation of (111)Pt//(001)SiC without reaction between Pt and SiC. A thin amorphous interlayer then forms at 400 °C. At 450 °C, a new crystalline phase nucleates discretely at the Pt-interlayer interface and projects into or across the amorphous interlayer toward the SiC, while the undisturbed amorphous interlayer between the newly formed crystallites maintains its thickness. These nuclei grow extensively down into the substrate region at 500 °C, and the rest of the Pt film is converted to Pt3Si. Comparison between the thermal reaction of SiC-Pt and that of Si–Pt is discussed.

The influence of a gold bulk contamination on the performances of boron doped p-type crystalline silicon solar cells is investigated for different base doping levels and different kinds of materials, such as float zone Si, Czochralski Si, and multicrystalline Si. Solar cells are made from intentionally contaminated silicon wafers. By monitoring the evolution of the electrically active substitutional gold concentration by means of bulk lifetime and minority carrier diffusion length measurements, this paper highlights the eventual gettering or hydrogenation effects occurring throughout the whole process but also of the danger of such an impurity in materials containing large densities of extended defects generating recombination centers by means of the impurity-defect interaction.

In this paper, the impact of iron contamination on the conversion efficiency of single-crystalline p-type silicon solar cells is investigated by means of the combination of numerical simulations and experimental data, taking into account the more recent results about the properties of iron in single-crystalline silicon. Numerical simulations highlight the fill factor losses due to the injection-level dependence of the bulk lifetime, which attenuates the decrease of the open circuit voltage and thus that of the solar cell conversion efficiency with iron concentration. Gettering and hydrogenation effects are quantified by means of experimental results obtained from voluntarily contaminated solar cells and integrated in the simulations. The results show that iron appears to be a metallic impurity rather well tolerated in p-type single-crystalline silicon solar cells, because its injection-level dependent bulk lifetime, like its abilities to be gettered and to be passivated by hydrogenation, limits its influence on the solar cell conversion efficiency.

Hydrogenated silicon nitride SiNx:H films are largely used as antireflective coating as well as passivation layer for industrial crystalline and multicrystalline silicon solar cells. This work is focused on the optical and photoluminescence (PL) properties of SiNx:H deposited by either Plasma-Enhanced Chemical Vapour Deposition (PECVD) or UltraViolet photo-assisted CVD (UVCVD). Photoluminescence phenomena were investigated in SiNx:H having different stoechiometries. On the other hand, spectroscopic ellipsometry was carried out in order to obtain the optical properties of the films, from which the optical gap could be determined. The evolution of the photoluminescence with stoechiometry was correlated to the evolution of the optical properties, and especially the absorption within the SiNx:H layer. A good agreement was found considering the confinement of excitons in strongly absorbing silicon nanostructures (ns-Si) formed in the SiNx matrix, with different sizes according to the NH3 / SiH4 gas flow ratio and the deposition technique. The main PL peak showed an increase of the emission intensity along with a blueshift as silicon concentration decreases. These observations indicate a radiative recombination mechanism dominated by confined excitons within ns-Si rather than emission related to defects. Furthermore, these ns-Si are supposed to be responsible of the global higher absorption, and hence lower optical gap, of the near-stoechiometric SiNx:H films in comparison with the stoechiometric Si3N4 ones. These assumptions were confirmed thanks to transmission electron microscopy (TEM) images performed on one of the samples, showing crystalline silicon quantum dots (c-Si QDs) embedded in the SiNx matrix.

A novel approach for the silicon thin-film solar cells transfer technology was developed at INSA-LYON, named ELIT process (Epitaxial Layers for Interdigitated back contacts solar cells Transferred using porous silicon). In this paper, all the process steps are described. Starting from the formation of a double porous silicon layer on the whole substrate surface, a high crystal quality Si layer is grown by Vapor Phase Epitaxy. This single crystal epitaxial layer is then processed into solar cells by realizing all the contacts on the back side. Finally, these rear contacts solar cells are transferred onto a glass plate and separated from the initial Si substrate before TMAH texturation and deposition of PECVD SiN antireflective coating on the front side. Interdigitated Back Contacts solar cells (IBC) with an efficiency of 7.7% and 8.2% were achieved

The MOVPE (Metal Organic Vapour Phase Epitaxy) growth of GaAs single-junction solar cells on layer transferred GaAs/Si-substrates is reported. This novel type of alternative substrates for III-V epitaxial growth was realised by performing the Smart Cuttrade technology. HRXRD-measurements proved good material quality by a FWHM of about 30 arcsecond reveal a dislocation density below 4times10 5 cm -2 for a 5 mum thick GaAs layer. Due to the formation of cracks the performance of GaAs single-junction solar cells has only been in the range of 12 %

We report the observation of random telegraph signals (RTS) occurring in the forward regime of silicon carbide Schottky diodes. RTS noise is attributed to the modulation of the conductivity either by the trapping/detrapping of a single electron or by the switching of a bistable defect, in the neighbourhood of a localized current path. Noise measurement is therefore a convenient and non-destructive method for assessing the defectivity of SiC power diodes.

We report the results of a series of optical investigations performed on both 6H and 4H epitaxial layers grown at low rate (≈1 μm h−1) in a home-made cold-wall chemical vapor deposition (CVD) reactor. To keep the level of contamination as low as possible, attempts have been made to investigate the origin of residual dopants. In this way, we have found that aluminum comes only from the use of uncoated graphite susceptors. When using a SiC coated susceptor, we have found that the protection is only effective for about ten runs.

To investigate the origin of the high level of electrical compensation induced by hydrogen-implantation during the fabrication of SiCOI (Silicon Carbide layer transferred On Insulator) structures we have performed a comparative investigation of the electrical and optical properties of, both, 6H–SiCOI structures and hydrogen-implanted 6H–SiC epitaxial layers. We have found that the high resistivity of SiCOI structures comes most probably from an effect of compensation by deep traps created during the implantation, rather than H-passivation of dopants. The D1-center, observed by photoluminescence after the high temperature treatment, and the Z1/Z2-center or C-defect, observed by deep level transient capacitance spectroscopy, could be the signature of these compensating centers.