Activation energies for mobility

Experimental mobility values, 1.2 X 10-2 cm2/v.s. for eam and 1.9 x 10-3 cm2/v.s. for eh, indicate a localized electron with a low-density first solvation layer. This, together with the temperature coefficient, is consistent with the semicontinuum models. Considering an effective radius given by the ground state wave-function, the absolute mobility calculated in a brownian motion model comes close to the experimental value. The activation energy for mobility, attributed to that of viscosity in this model, also is in fair agreement with experiment, although a little lower. 

The vacancy is very mobile in many semiconductors. In Si, its activation energy for diffusion ranges from 0.18 to 0.45 eV depending on its charge state, that is, on the position of the Fenni level. Wlrile the equilibrium concentration of vacancies is rather low, many processing steps inject vacancies into the bulk ion implantation, electron irradiation, etching, the deposition of some thin films on the surface, such as Al contacts or nitride layers etc. Such non-equilibrium situations can greatly affect the mobility of impurities as vacancies flood the sample and trap interstitials. 

Notice that the energy of the ion is the same at the beginning and the end of the jump the energy required to make the jump, E, is known as the activation energy for the jump. This means that the temperature dependence of the mobility of the ions can be expressed by an Arrhenius equation ... 

It hag been shown that transition of a backbone carbon from the sp to sp state is promoted by tensile stresses and inhibited by compressive strains (10,44). The acceleration of the process of ozone oxidation of the polymers under load is not associated with the changes in supramolecular structure or segmental mobility of the chain. The probably reason of this effect is a decreasing of the activation energy for hydrogen abstraction (44). The mechanism of initial stages of the reaction of ozone with PP can be represented as ... 

The activation energy for conduction, is the major factor controlling the ionic mobility, u. The Arrhenius expression for conductivity is either... 

Step-mobilities for Ge(OOl) using Eq. 14 are included in Fig. 6 by scahng the annealing temperature by the ratio of the cohesive of energy of Si to Ge, 1.20 [32]. In other words, to enable a comparison between the Ge and Si experiments, we assume that activation energies for Si(OOl) are 1.20 times larger than the equivalent activation energies for Ge(OOl). 

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