Spectral supralinearity of silicon photodiodes with over-filled illumination in the near-infrared region.

Abstract

The spectral nonlinearities of silicon (Si) photodiodes (PDs) with over-filled illumination in the near-infrared region were investigated under reverse-bias and zero-bias voltage conditions. The supralinear behaviors and their wavelength dependences were clearly observed with over-filled illumination under both the reverse-bias and zero-bias voltage conditions at the selected wavelengths. Comparing these results with the nonlinearity results obtained in the under-filled illumination condition, it was evident that the maximum supralinearity values observed under the over-filled illumination condition were larger than those in the under-filled illumination condition, and the maximum value (∼10%) was obtained at the incident wavelength of 1060 nm. To validate the relatively large supralinearity value obtained under the over-filled illumination condition in the near-infrared region, the linearity factor and the photocurrent, as a function of the Si PD positions, and their wavelength dependences were examined under both the reverse-bias and zero-bias voltage conditions at all wavelengths. The linearity factors at the selected wavelengths, under both conditions, exceeded unity at all the PD positions; specifically, the values near the PD electrode were larger than those near the PD center, although the examined photocurrent decreased as the laser beam strayed off the beam detection area of the Si PD. These results highlighted that the relatively large supralinearity was generated under the over-filled illumination condition and that the minority carrier traps for the supralinearity-generating recombinations exist not only near the PD center but also near the PD electrode. These experimental results can facilitate the 3D theoretical modeling of Si-based photodetectors and aid the achievement of high-accuracy measurements with Si PDs in the fields of radiometry and radiation thermometry.