The Potential Distribution at the Semiconductor/Solution Interface

Abstract

In semiconductor electrochemistry there is considerable confusion concerning the potential distribution at the semiconductor/solution interface under weak depletion and accumulation conditions. The applied potential is partitioned between the space charge layer in the semiconductor and the Helmholtz layer on the solution side of the interface. Under deep depletion conditions, a change in the applied potential usually appears across the space charge layer and the band bending can be determined using the Mott-Schottky relation. Under conditions of weak depletion or accumulation, however, the applied potential is partitioned between the two double layers and determination of band bending is not straightforward. In this paper, expressions for the dependence of the band bending on the applied potential are derived and the consequences for chargetransfer processes are discussed.

Corrosion modelling of iron based alloy in nuclear waste repository

“…Searson and coworkers [43] have shown that the seeming cathodic Tafel slope could be modified by the structure of the interface. These authors have used an equivalent electrical circuit to describe the sharing of voltage drops between the space charge layer and the Helmholtz layer.…”

“…32), but V pzc 0 were equal to V fb . The shift between V fb and V pzc 0 has been emphasized [43,56] to occur when the space charge layer capacitance is too high and not negligible in front of 0 . This was actually the case for magnetite bur not for the slightly reduced maghemite for which the value of the space charge layer capacitance was about 30 times lower than the one for magnetite (cf.…”

Inner-Helmholtz potential development at the hematite (α-Fe2O3) (001) surface

“…If the reference electrode exhibits constant potential independent of the solution composition, changes in E as a function of pH, ionic strength, electrolyte composition, and adsorbate concentration arise from reactions at the mineral/solution interface. Multiple planes of charge can be specified that dictate the total potential drop across this interface, including the space charge layer in the mineral surface, the Helmholtz layer, and the diffuse layer in solution (as opposed to just the latter two for insulators) (Garrett and Brattain, 1955;Morrison, 1980;Natarajan et al, 1998). As will be discussed below, for conditions where the voltage drops across two of the three layers are understood, the third can be directly determined.…”

On the Structure of the Helmholtz Layer and its Implications on Electrode Kinetics

“…The latter is known for H-terminated Si and the values for higher doped samples have been calculated taking into account the deviation from the Boltzmann approximation for very high doped samples (using the FermiDirac integral values). For the determination of the respective potential drop in the space charge layer, V SC , we use the expression [42]: (8) and Table I shows the evaluation. The left four columns give doping level, onset potential for the current, the flatband potential and the difference V on -V fb .…”