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Tuning the shape of macroporous silicon

Macroporous silicon membranes, prepared by photo‐electrochemical etching, were subjected to pore widening performed by multiple oxidation/oxide‐stripping cycles. We study the dependence of pore cross section and diameter on the oxidation parameters. The anisotropy of the oxidation process allows us to correct the faceted pore shape after the etching and to obtain pores with circular cross section. The shown post‐treatment of macroporous silicon extends the possibilities of the electrochemical etching process to produce structures with a desired geometry. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)