Electronic states amplitude fluctuations

The adiabatic limit in this case corresponds to the situation where an electron is emitted from the localized acceptor state into the conduction band whenever large-amplitude fluctuations of atoms push the acceptor level up to the conduction-band... 

A typical example of a special state is as follows. Electron transfer reactions at an atom are aided by vibrations that equilibrate the interatomic distances that differ for the two oxidation states. Thus a low-energy, high-amplitude vibration is desirable. The vibration could have the further function that it provided a time-dependent fluctuation of the redox potential. As I and Goldanskii in this volume have pointed out, this allows a precise matching of the redox potential of one redox couple with another leading to tunneling of electrons. 

The amplitude and spatial dimensions of the potential fluctuations are different in undoped, doped, and compensated a-Si H. The band tail electrons and holes provide the mobile screening charge in doped a-Si H and the doping dependence of the potential fluctuations can be estimated from the experimental data. The magnitude of n. depends on the thermal equilibrium state, but is usually about 10 % of the donor and defect density. According to the square root law for doping,... 

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