Hole and electron conduction

An explanation of the effect nature, compatible with the experimental data, was proposed by B. Kadomtsev [3]. It is based on assumption, that the atom, flying over the metal surface, interacts with the conductive electrons and holes in a thin surface layer. This results in an entangled state of the atom with a huge number of electrons and holes. Such an interaction gives rise to appearance a coherent admixture of the 2P-state to initial state 2S. The amount of this addition from each individual electron is infinitesimally small, but the net effect is observable because of great number of electrons. Thus, according to Kadomtsev, the effect observed is due to coherent superposition of EPR-interactions, and ought to be considered in terms of correlations (like Pauli-principle) rather than in terms of forces. 

The ionic charge carriers in ionic crystals are the point defects.1 2 23,24 They represent the ionic excitations in the same way as H30+ and OH-ions are the ionic excitations in water (see Fig. 1). They represent the chemical excitation upon the perfect crystallographic structure in the same way as conduction electrons and holes represent electronic excitations upon the perfect valence situation. The fact that the perfect structure, i.e., ground structure, of ionic solids is composed of charged ions, does not mean that it is ionically conductive. In AgCl regular silver and chloride ions sit in deep Coulomb wells and are hence immobile. The occurrence of ionic conductivity requires ions in interstitial sites, which are mobile, or vacant sites in which neighbors can hop. Hence a superionic dissociation is necessary, as, e.g. established by the Frenkel reaction ... 

Fig. 5.10 Conduction electrons and holes can be created energetically more easily from donor or acceptor states, that occur within the band gap. If the distances to the band edges (at T=0 in a pure semiconductor, LU and HO...

Remarkably, although band stmcture is a quantum mechanical property, once electrons and holes are introduced, theit behavior generally can be described classically even for deep submicrometer geometries. Some allowance for band stmcture may have to be made by choosing different values of effective mass for different appHcations. For example, different effective masses are used in the density of states and conductivity (26). 

Sihcon (33) is a semiconductor and thus the electrical conductivity. O, is deterrnined by contributions from both electrons and holes, ie,... 

The relatively high mobilities of conducting electrons and electron holes contribute appreciably to electrical conductivity. In some cases, metallic levels of conductivity result ia others, the electronic contribution is extremely small. In all cases the electrical conductivity can be iaterpreted ia terms of carrier concentration and carrier mobiUties. Including all modes of conduction, the electronic and ionic conductivity is given by the general equation ... 

Where b is Planck s constant and m and are the effective masses of the electron and hole which may be larger or smaller than the rest mass of the electron. The effective mass reflects the strength of the interaction between the electron or hole and the periodic lattice and potentials within the crystal stmcture. In an ideal covalent semiconductor, electrons in the conduction band and holes in the valence band may be considered as quasi-free particles. The carriers have high drift mobilities in the range of 10 to 10 cm /(V-s) at room temperature. As shown in Table 4, this is the case for both metallic oxides and covalent semiconductors at room temperature. 

It is to be expected that tire conduction data for ceramic oxides would follow the same trends as those found in semiconductors, i.e. the more ionic the metal-oxygen bond, the more the oxides behave like insulators or solid elee-trolytes having a large band gap between the valence electrons and holes, and... 

As is customary, the conductivity is described by independent transport of electrons and holes such that... 

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