The Potential Distribution at the Semiconductor/Solution Interface

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 charge-transfer processes are discussed.