Potential distribution across the electrode interface

The total potential A/ across the electrode interface may be expressed approximately by using the thickness of space charge layer approximated by the Debye length Ld.9c, the thickness of compact layer du, and the thickness of 

In Eqn. 5-65 it appears that most of the change of electrode potential occurs in the space charge layer with almost no change of potential both in the compact layer and in the diffuse layer. This pattern may be regarded as characteristic of semiconductor electrodes. 

In the case in which the charge of the surface state exists at the electrode interface, electrostatics gives Eqn. 5-66 in place of Eqn. 5-64  

If the surface state charge a is relatively great, the potential of the compact layer, is given by Eqn. 5-67  

The potential i t sc of the space charge layer can also be derived as a fixnction of the surface state charge Ou (the surface state density multiplied by the Fermi function). The relationship between of a. and M sc thus derived can be compared with the relationship between and t R (Eqn. 5-67) to obtain, to a first approximation, Eqn. 5-68 for the distribution of the electrode potential in the space charge layer and in the compact layer [Myamlin-Pleskov, 1967 Sato, 1993]  

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