The effect of diffusion on the impulse response of RCE detector

We present a theory which demonstrates how the diffusion of photogenerated carriers affects the impulse response of a resonant-cavity enhanced photodetector (RCE). Analytic expressions for carrier densities and short-circuit current are derived, The theory indicates that diffusion introduces a significant tail in the temporal response of photodetectors. The influence of diffusion rises as the absorption width decreases, and a discrepancy in bandwidth as high as 35% between our results and previous theoretical predictions is observed. Therefore, the effect should be taken into account while calculating the critical parameters of RCE photodetectors with thin absorption region.