Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 46: Photovoltaics (joint session HL/CPP/O)

CPP 46.12: Talk

Friday, March 15, 2013, 12:15–12:30, H2

Surface morphology of black silicon produced by metal-catalyzed wet etching — •Maximilian Bernt, Michael Algasinger, Svetoslav Koynov, and Martin Stutzmann — Walter Schottky Institut, Technische Universität München, 85748 Garching, Germany

Nano-textured silicon, also referred to as black silicon (b-Si), is a material with an optically graded surface, which shows reflectivity as low as 1 - 5 % in the whole range of Si absorption and additional light trapping effects. Due to its unique optical properties, b-Si is an interesting material for photovoltaic applications. However, b-Si produced by Au-catalyzed wet etching of crystalline Si (c-Si) wafers exhibits a nano-porous silicon (np-Si) phase in the as-prepared nano-structure. This np-Si phase leads to an increased surface area which could alter the electrical properties significantly. The formation of the nano-texture was investigated at different stages of the etch process by cross sectional scanning electron microscopy. The evolution of the np-Si phase with increasing etch time was observed by photoluminescence and optical reflectivity measurements. In addition, the influence of the doping level of n- and p-type c-Si substrates on the etch process and the morphology of the resulting nano-texture was studied.