Transport in Semiconductors Junctions

In conclusion, we observe that the crossing of crystal phase boundaries by matter means the transfer of SE s from the sublattices of one phase (a) into the sublattices of another phase (/ ). Since this process disturbs the equilibrium distribution of the SE s, at least near the interface, it therefore triggers local SE relaxation processes. In more elaborated kinetic models of non-equilibrium interfaces, these relaxations have to be analyzed in order to obtain the pertinent kinetic equations and transfer rates. This will be done in Chapter 10. 

We have discussed transport in the bulk and transport across interfaces and phase boundaries (i.e., discontinuities). In this section, we shall mainly treat an intermediate transport situation, the so-called junction. At junctions, the atomistic processes that occur under a load have much in common with interface processes, such as the relaxation behavior of the SE s which are swept across them. 

Fick s second law states the conservation of the diffusing species i no i is produced (or annihilated) in the diffusion zone by chemical reaction. If, however, production (annihilation) occurs, we have to add a (local) reaction term r, to the generalized version of Fick s second law c, = —Vjj + fj. In Section 1.3.1, we introduced the kinetics of point defect production if regular SE s are thermally activated to become irregular SE s (i.e., point defects). These concepts and rate equations can immediately be used to formulate electron-hole formation and annihilation 

The second term on the right hand side accounts for the bimolecular recombination reaction (see, for example, Eqn. (1.2) //.). 

if the length of the one dimensional recombination zone rs di the steady state condition in Eqn. (4.121) for the minority species in this zone simplifies to 

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