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Based on recent advancements of radial junction silicon nanowire (RJ SiNWs) solar cells, a demonstration of $5\mathrm{x}5 \pmb{\mathrm{cm}^{2}}$ RJ $\mathbf{SiNW}$ solar mini-module is presented in this work. The $\mathbf{SiNW}$ devices were grown by plasma-assisted vapor-liquid-solid technique at low temperature in a plasma-enhanced chemical vapor deposition reactor. The $\pmb{5\mathrm{x}5\ \mathrm{cm}^{2}}$ mini-modules have been obtained using a commercial laser scribing apparatus. The laser scribing insures a monolithic integration of electrically separated cells. We have obtained a power generation of 10 $\mathbf{mW}$ from 5 individual cells of total active area of 8.6 $\pmb{\mathrm{cm}^{2}}$. The mini-module has an open-circuit voltage of 3.85 V. The performance was evaluated using solar simulator and short comings (high series resistance) were analyzed using a home-made electroluminescence setup.

Recent developments have unlocked the main issues arising from the combination of III-V and silicon and have opened a new way to fabricate tandem solar cells. We here propose to evaluate such tandem concept based on inverse metamorphic growth of c-Si(Ge) on GaAs by means of numerical simulation. Electrical and optical models are first faced to experimental realizations of single junction cells to calibrate material parameters and to assess the electrical quality of the epi-SiGe layer. Then the tandem structure is optimized, current matching conditions are given and the benefit of using a 2D grating at the back-side is studied.

The use of Kelvin Probe Force Microscopy to investigate PN junctions under illumination and electrical bias has been shown to be an effective way to analyze the electrical properties of solar cells at the nanoscale. We use it here, for the first time, on interdigitated back contact solar cells. Measurements are performed between the metallic fingers under an electrical bias in the dark and under illumination in open circuit conditions. Our results show that that KPFM could be used to identify and localize diodes resistance losses at the nanoscale.

In this work we show the application of the angle-resolved spectroscopic reflectivity and polarimetry to the characterization of 2D photonic crystal structures in the form of slabs. The method we introduce is based on the combination of i) the numerical simulation of the interaction of the incident light with the photonic crystal, ii) the experimental measurement and iii) the comparison of both results. We show that the calculations predict the coupling of the incident light to photonic modes propagating inside the structure, related to the photonic bands of the infinite photonic crystal. We demonstrate this coupling in the experimental measurements for two kinds of samples consisting of 2D photonic crystal slabs of micro- and nanostructured photoresist on a silicon substrate.