Liquid-phase crystallized silicon absorber layers have been applied in heterojunction solar cells on glass substrates with 10.8% conversion efficiency and an open-circuit voltage of 600 mV. Intermediate layers of SiO x , SiN x , and SiO x N y , as well as the a-Si:H precursor layer, were deposited on 30 cm × 30 cm glass substrates using industrial-type plasma-enhanced chemical vapor deposition equipment. After crystallization on 3 cm × 5 cm area using a continuous-wave infrared laser line, the resulting polysilicon material showed high material quality with large grain sizes. Index Terms-Heterojunction, liquid-phase crystallization, plasma-enhanced chemical vapor deposition (PECVD), thin-film silicon.

Amorphous diamond-like carbon films were irradiated with high-energy heavy ions like 1 GeV uranium or 340 MeV gold. The large energy deposition along the ion track leads to a transformation of the material from insulating diamond-like to conducting graphite-like carbon. The ion tracks form thin straight channels (nanowires) with a diameter of approximately 8 nm and a conductivity of the order of 1–10 S/cm. The conductivity in the tracks is up to eight orders of magnitude larger than in the surrounding material. The surface topography and the conduction properties of these channels were studied with an atomic force microscope.

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The influence of the transparent conducting oxide (TCO) topography was studied on the performance of a silicon oxide intermediate reflector layer (IRL) in a-Si/μc-Si tandem cells, both experimentally and by 3-D optical simulations. Therefore, cells with varying IRL thickness were deposited on three different types of TCOs. Clear differences were observed regarding the performance of the IRL as well as its ideal thickness, both experimentally and in the simulations. Optical modeling suggests that a small autocorrelation length is essential for a good performance. Design rules for both the TCO topography and the IRL thickness can be derived from this interplay. Index Terms-3-D rigorous optical modeling, a-Si/μc-Si, intermediate reflector, micromorph, solar cells, transparent conducting oxide (TCO). I. INTRODUCTION AND BACKGROUND A S THE demand for affordable clean energy grows, amorphous silicon (a-Si) / microcrystalline silicon (μc-Si) tandem solar cells are an interesting technology, as it combines nontoxic and abundant materials with a low temperature/low cost process. However, the conversion efficiency of these de-Manuscript