Dependence of the flat-band potential of n-type GaAs on the redox potential in methanol and acetonitrile

Photoelectrochemical Behavior of n-Type GaAs(100) Electrodes Coated by a Single Layer of Graphene

“…These data clearly indicate that partial Fermi-level pinning is present in this system over the wide range of solution potentials that was investigated. Partial Fermi-level pinning of GaAs/CH 3 CN contacts has been observed previously in cyclic voltammetric and/or impedance studies. − The observation that GaAs electrodes can produce a photovoltage even at the most negative cell potential has been attributed to the pinning of the Fermi level by surface states. Even when a single layer of graphene was inserted between the GaAs and CH 3 CN, the n-GaAs/Gr contact exhibited exactly the same effects of partial Fermi-level pinning as the n-GaAs/CH 3 CN contacts (Figure ).…”

Picosecond Photoluminescence Study of then-GaAs(100)/Methanol Interface in a Photoelectrochemical Cell

“…The working electrode typically had a dark open circuit voltage ( V oc ) of −0.42 V vs Ag/AgNO 3 immediately after introduction to the cell. According to work by B. Ba et al, the flat band potential ( V fb ) for the n -GaAs/methanol cell is −1.5 V vs Ag/AgNO 3 . V fb was verified by Mott−Schottky analysis.…”

“…The effect of water contamination in the methanol cells can be monitored by spiking the cell with small water additions. Second, there are a variety of outer-sphere redox couples available that are stable in methanol with equilibrium potentials within the band gap of n -GaAs. The ferrocene/ferricenium couple was chosen for this study because its equilibrium potential is close to the n -GaAs valence band edge and because of the extent of information available on it in the literature.…”

Surface states mediated charge transfer in redox behavior of hemin at GaAs(100) electrodes

“…In principle, the inuence of a redox couple on the apparent at band potential, E FB , could be due either to adsorption of the redox components 52 or to Fermi level pining at the redox potential of the solution couple. [53][54][55][56][57] The shi of E FB up to the redox potential of the hemin/hem couple found at the p-doped hemin-modied electrodes is considered to be the result of the electronic equilibrium between the redox potential of the couple and the semiconductor surface states situated above the valence band edge. In the j/E proles recorded during the EIS measurements illustrated in Fig.…”