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A solar cell design is presented that allows energy conversion in solid-state photovoltaics as well as in photoelectrochemical and photoelectrocatalytic cells. The energy-converting structure uses a Schottky-type, ͑i.e., metallic͒ nanoemitter, prepared by an oscillatory ͑photo͒electrochemical process. Silicon shows ͑photo͒current oscillations in fluoride-containing electrolytes that form an oxide with interspersed nanopores. Spatially selective electrodeposition of Schottky-barrier metals into these pores produces the nanoemitter contacts. The n-Si/SiO 2 /Pt/redox electrolyte structure shows pronounced photoactivity in a photoelectrochemical cell. Light-induced hydrogen evolution is obtained for structures made with p-Si. The energy-band alignments of the structures are discussed and routes for preparation of efficient solid-state devices are outlined.

The transition from sustained to damped current oscillations or to stationary behavior is described using a model based on morphological aspects. A roughening of the oxide and of the underlying Si surface is predicted, in accordance with measurements. The role of cracks and nanopores in silicon oxide is discussed with regard to roughness increase and macropore formation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Chronoamperometric conditioning of float zone n-Si(111) in 2M NaOH solution in the potential range negative from open-circuit potential is performed in a combined electrochemistry/ultrahigh-vacuum surface analysis experiment. Synchrotron Radiation Photoelectron Spectroscopy measurements at the U49/2 beamline at Bessy II using the SoLiAs facility show formation of a ultrahigh-vacuum-stable permanent accumulation layer without junction formation. Comparison of the Thomas–Fermi screening potential and the mean inelastic scattering length λesc of photoelectrons at hν=150eV (λesc=4Å) and hν=585eV (λesc=15Å) indicates a surface electron concentration of 3×1018cm−3 for a bulk doping level of 1015cm−3. The observed shift of the Si2p3∕2 and 2p1∕2 core level with photon energy is in excellent agreement with the shifted onset of the x-ray photoelectron spectroscopy valence-band spectrum measured at hν=150eV.