Supralinear behavior and its wavelength dependence of silicon photodiodes with over-filled illumination in visible range.

Spectral supralinear behavior of silicon (Si) photodiodes (PDs) with over-filled illumination in the visible region was investigated. Comparing the results with the supralinearity results in under-filled illumination conditions, the supralinearities of the Si PDs with over-filled illumination sharply increased at the photocurrent over hundreds of nA, and the maximum supralinearity value of approximately 5% was observed at the 405-nm wavelength. To validate the supralinearity increase under over-filled illumination in visible light, the linearity factor and the photocurrent relating to the Si PD position and their wavelength dependence were examined. The linearity factors increased as the laser beam approached the Si PD electrode as well as with decreasing wavelength, although the examined photocurrent decreased as the laser beam strayed off the beam detection area of the Si PD. These results show that the supralinearity with over-filled illumination in the visible region was caused by the recombination losses near the Si PD electrode. These experimental results can help obtain accurate measurements with photometry instruments constructed of Si PDs and for the three-dimensional theoretical modeling of the Si photo devices.