Charge-separation model energy requirement

The model of Cabrera and Mott is discussed in die book on low-temperature oxidation by Fehiner [5b]. The basis of the model is die quantum mechanical concept of electron tunneling. An electron can penetrate an energy barrier without die requirement for thermal activation. As soon as a three-dimensional oxide forms on a metal, electrons tunneling through the oxide are captured by adsorbed oxygen on die oxide surface. The charge separation thus established between die oxide surfece and the metal sets up an electric field across the oxide. The proposed mechanism is illustrated in Figure 1. 

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