Differences in p-side and n-side illuminated p-i-n photodiode nonlinearities

The advantages of illumination through the p-contact of p-i-n photodetectors are experimentally and numerically studied. Nonlinearity and compression current measurements are compared to simulations of harmonic distortion for a 3-GHz p-side-illuminated photodiode to further our understanding of signal compression. It is shown that the 1-dB compression current may be improved by an order of magnitude for capacitively limited detectors simply by illumination from the p-side. This effect is attributed to the decreasing hole velocity at low electric fields and the steady-state carrier density distributions at high current levels.