Quantitation quasi-equilibrium theory

In the theory of non-equilibrium processes at solid state junction and also semiconductor-liquid interfaces, as developed in the previous section, frequently quasi-Fermi levels have been used for the description of minority carrier reactions [90, 91], A concept for a quantitative analysis for reactions at n- and p-type electrodes has been derived [92, 93], using the usual definition of a quasi-Fermi level (Eqs. (3a) and (3b)). Taking a valence band process as an example, the quasi-Fermi level concept can be illustrated as follows ... 

The situation is quite different if minority carriers are involved. Then electrons and holes are not in equilibrium and their quasi-Fermi levels become different. In the case of an n-type semiconductor, f,p can be located above or below depending on the minority carrier process, i.e. on whether minority carriers are extracted from or injected into the semiconductor. However, quasi-Fermi levels have been qualitatively used in the theory of non-equilibrium processes in solid state devices, such as the excitation and recombination of electrons and holes (see Section 1.6), and also for the descriptions of charge transfer processes in p-n junctions (see Section 2.3). In this section a quantitative analysis of reactions at n- and p-type electrodes in terms of quasi-Fermi levels will be derived [19, 54]. 

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