Transition Region Recombination Current Density

Using (6.15) in (5.5), the band-band recombination current density due to the transition region is 

SO that only a weak n dependence is left inside the braces in (8.2) and (8.3). Thus J (bb) depends mainly as (exp n - 1) on the voltage 

For narrower band gaps the ratio will be smaller and a value of 100 has been adopted in fig. 8.1. Even so, the Auger effect increases the recombination current only slightly. For large enough - n 

The recombination current via traps in the transition region will be considered next, and this requires the second term in (6.15), As there are now six recombination coefficients, let us suppose for simplicity that 

Thus if higher forward voltages are developed so that single-electron trapping effects dominate 

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Fig. 8.2 The transition region recombination current density via traps according to equation (8.11). Key to the curve...

The transition region recombination current density depends on the voltage developed across the junction through a factor (exp n " 1), but the integral... 

As an example of a recombination current density calculation consider the transition region of a p-n junction, fig. 7.1. Band edges and quasi-Fermi levels are... 

Fig. 8.1 The transition region band-band recombination current density according to equation (8.3) with x)jy = 20.

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