Semiconductor generalized equivalent circuit

Figure 2. Assumed generalized equivalent circuit of the semiconductor—electrolyte interface. Reduced equivalent circuit at high frequencies and the expression for the impedance at low and high frequencies.

Power law behaviour has also been observed by Dutoit et al. [73] and ascribed to more general relaxation processes within a narrow layer at the surface of the semiconductor. It is, of course, not possible to distinguish by a.c. techniques alone the model put forward by Dutoit et al. [73] and that described above since the mathematical development is the same and the differences may, in any case, be largely semantic. Nevertheless, Dutoit et al. s analysis is of considerable interest. An equivalent circuit of the form... 

Surface states can be determined for semiconductor-solution interfaces (38) by making measurements of the capacitance of the semiconductor-solution interface and then by producing equivalent circuits which simulate the measurement to the best extent. An example is given (Fig. 15) which shows the surface states for gallium phosphide as a function of potential. Here, concentration of surface states is large, corresponding to the second model of the interface. This seems likely to be the most general case because of the presence in the double layer of adsorbed ion and solvent molecules. 

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