Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 84: Photovoltaics (jointly with CPP, DS and HL)
O 84.11: Talk
Friday, March 15, 2013, 12:00–12:15, H2
Surface Modification of Nano-Textured Black Silicon for Photovoltaic Applications — •Michael Algasinger1, Svetoslav Koynov1, Julie Paye1, Florian Werner2, Max Bernt1, Martin S. Brandt1, and Martin Stutzmann1 — 1Walter Schottky Institut, Technische Universität München, 85748 Garching, Germany — 2Institute for Solar Energy Research Hamelin, Am Ohrberg 1, 31860 Emmerthal, Germany
The morphology and the electronic properties of nano-textured silicon, obtained by a metal-catalyzed wet etching process and its improvement by an additional chemical treatment are examined with regard to solar cell applications. Photoluminescence and optical reflectivity measurements show evidence for a nano-porous silicon (np-Si) phase in the as-prepared nanostructure. It is found that an additional wet-chemical treatment removes the np-Si fraction and significantly alters the surface of the nanostructure. Cross-sectional scanning electron microscopy images reveal a drastic reduction of the surface area, to values of only 3 - 6 times of that of a planar surface. Electron spin resonance measurements were performed to investigate the type and quantity of defects induced by the nano-texturing process. First results on the passivation of surface defects via atomic layer deposition of Al2O3 are presented. Photoconductance decay measurements of passivated nanostructures, which received the additional post-etching treatment, show a significant increase in effective carrier lifetimes.