Profiling Photoinduced Carrier Generation in Semiconductor Microwire Arrays via Photoelectrochemical Metal Deposition

Abstract

Au was photoelectrochemically deposited onto cylindrical or tapered p-Si microwires on Si substrates to profile the photoinduced charge-carrier generation in individual wires in a photoactive semiconductor wire array. Similar experiments were repeated for otherwise identical Si microwires doped to be n-type. The metal plating profile was conformal for n-type wires, but for p-type wires was a function of distance from the substrate and was dependent on the illumination wavelength. Spatially resolved charge-carrier generation profiles were computed using full-wave electromagnetic simulations, and the localization of the deposition at the p-type wire surfaces observed experimentally correlated well with the regions of enhanced calculated carrier generation in the volumes of the microwires. This technique could potentially be extended to determine the spatially resolved carrier generation profiles in a variety of mesostructured, photoactive semiconductors.

Localized photodeposition of catalysts using nanophotonic resonances in silicon photocathodes

“…The experimentally observed deposition profiles match reasonably well with optical simulations of the photogenerated charge carrier distribution for each shape and wavelength. Most notably, deposition profiles far from those expected from a simple Beer–Lambert law have been obtained, in contrast to previous related work on silicon microwires [32–33]. Our results provide the first step for rationally designed catalyst positioning using the underlying resonant properties of nanoscale photocatalysts, tunable simply by altering the shape, size or excitation wavelength.…”

Template-Free Synthesis of Periodic Three-Dimensional PbSe Nanostructures via Photoelectrodeposition

“…Arrays of semiconductor mesostructures have been extensively developed for electronic, photonic, and sensing applications due to unique physical properties realized by patterning at the micro- and nanoscale. − Conventional photolithographic patterning involves selective exposure of a chemical resist using a spatially structured optical field produced by a physical photomask. Patterning can alternatively be achieved, without a mask or structured optical fields, by methods that exploit inherent asymmetries in light–matter interactions. , These techniques can provide control of the structural evolution and morphology of a deposit by manipulation of the character of illumination (e.g., wavelength), and generate features on length scales below the optical diffraction limit despite using spatially conformal excitation.…”

Light-addressable Electrodes for Dynamic and Flexible Addressing of Biological Systems and Electrochemical Reactions

“…As long as no overpotential is applied, deposition only occurs during illumination. Gold was also used on three-dimensional silicon microwires by applying −1.25 V vs. V Ag/AgCl in 0.01 M HAuCl 4 solution [102]. Anisotropic Au deposition was demonstrated by using cylindrical microwires, whereby the gold position on the microwires mainly depends on the illumination wavelength.…”