Activated hopping

The treatment of the time-dependent equation (4.1.23) has shown [55] that the transient kinetics is controlled by three parameters the ratio of the diffusion coefficients, D = D T2)/D T ) = exp(— a<5iyif)) (5T = T2 — T is temperature increment), oor /D and r /D. The first parameter, >, defines an increase in recombination intensity I(T2)/I(T ) (vertical scale) and thus permits us to get the hopping activation energy Ea. The parameter r /D could be found by fitting the calculated transient time to the experimentally observed one (horizontal scale). 

With respect to the electronic structure, several influences of the C atoms are indicated in the quotient reflectivity spectrum in Fig. 25 (114). Most important for the transport properties are the effects at and within the band gap. The interband photoconductivity (105) increases, the spin density of trapped electrons increases (see Ref. 58), and the hopping activation energy (see... 

More recently, D. Emin [24] developed an alternative analysis of activated hopping by introducing the concept of coincidence. The tunneling of an electron from one site to the next occurs when the energy state of the second site coincides with that of the first one. Such a coincidence is insured by the thermal deformations of the lattice. By comparing the lifetime of such a coincidence and the electron transit time, one can identify two classes of hopping processes. If the coincidence lime is much laigcr than the transit lime, the jump is adiabatic the electron has lime to follow the lattice deformations. In the reverse case, the jump is non-adia-batic. 

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