  The recombination rate in the space charge region (SCR) of a silicon-based
barrier structure with long Shockley-Reed-Hall lifetime is calculated
theoretically taking into account the concentration gradient of excess
electron-hole pairs in the base region. The effects of the SCR lifetime and the
applied voltage on the structure's ideality factor are analyzed. The ideality
factor is significantly reduced by the concentration gradient of electron-hole
pairs. This mechanism provides an increase of the effective lifetime compared
to the case when it is insignificant, which is realized at sufficiently low
pair concentrations. The theoretical results are shown to be in agreement with
experimental data.
