Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 10: Preparation and characterization

HL 10.5: Talk

Monday, February 25, 2008, 10:30–10:45, EW 202

Photoelectrochemical Formation and Shaping of Silicon Nanostructures Controlled by in-situ Brewster-Angle Reflectometry — •Michael Lublow and Hans-Joachim Lewerenz — Hahn-Meitner-Institut Berlin GmbH, Glienicker Str. 100, 14109 Berlin

Silicon nanostructures were produced and manipulated in ammonium fluoride containing solutions at small potentials positive from the open-circuit potential (OCP). In diluted solutions, either divalent or tetravalent electrochemical reactions can be induced by light intensity variations which consequently alter the OCP and therefore the resulting overpotential. During photon flux variation, formation and selective oxidation of the structures were monitored in real-time by the surface sensitive signal of Brewster-angle reflectometry. After subsequent oxide removal, varied aspect ratios and densities of the nanostructures were obtained. Structure alignment effects were analyzed by Atomic Force Microscopy and could be related to the wafer-miscut dependent topographies of the initially H-terminated surfaces. Results for varying miscut angles from 0° to 4° will be presented. The influence of solution concentration and different surface orientations towards (111), (100) and (113) direction will be discussed.