title: Radical formation at the gallium nitride nanowire-electrolyte interface by photoactivated charge transfer.
abstract: We investigated the transfer of photogenerated charge carriers from GaN nanowires into a surrounding electrolyte by electron paramagnetic resonance (EPR) and fluorescence spectroscopy. Using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap we find that the formation of hydroxyl radicals dominates in acidic, neutral and moderately basic environments, while in an electrolyte with a pH of 13.5 the superoxide formation becomes detectable. We explain the two processes considering the redox potentials for radical formation in the electrolyte as well as the positions of the conduction and valence bands. The role of surface band bending and surface states in the semiconductor is discussed.
authors.affiliation: I. Physikalisches Institut, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Gießen, Germany. jan.m.philipps@physik.uni-giessen.de
authors.forename: J M
authors.initials: JM
authors.lastname: Philipps
authors.forename: G M
authors.initials: GM
authors.lastname: Müntze
authors.forename: P
authors.initials: P
authors.lastname: Hille
authors.forename: J
authors.initials: J
authors.lastname: Wallys
authors.forename: J
authors.initials: J
authors.lastname: Schörmann
authors.forename: J
authors.initials: J
authors.lastname: Teubert
authors.forename: D M
authors.initials: DM
authors.lastname: Hofmann
authors.forename: M
authors.initials: M
authors.lastname: Eickhoff