Thermal and optical generation current in reverse-biased gold-doped silicon p+n junctions without the depletion approximation

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Abstract
Optical and thermal generation currents in reverse‐biased p‐n junctions have been calculated for an exponential tail of free‐charge carriers extending from the neutral regions into the transition region. Net generation of electron‐hole pairs can then be neglected at the ends of the transition region because of recombination processes. The width W0 of these regions has been calculated for step junctions and asymmetrical linearly graded junctions. For a symmetrical step junction, W0 is independent of bias at constant illumination intensity. For a linearly graded junction, however, the widths of these regions become monotonically smaller with increasing reverse bias. In all cases, the regions with negligible net generation decrease logarithmically with intensity. The calculations are in good agreement with experimental results for gold‐doped silicon diodes. Furthermore, it is shown that, for moderate average electric fields, neither the optical nor the thermal hole emission rate for the gold acceptor in silicon is field dependent.