Monolithic silicon avalanche photodetector utilizing surface state defects operating at 1550 nm

In this work, we report on all-silicon waveguide photodetectors utilizing surface state defects and bulk defects to sensitize the silicon to sub-bandgap light. The detectors are foundry fabricated, waveguide-integrated p-i-n junctions with post-processing consisting of HF acid exposure, ion implantation, annealing, or a combination of the three. HF exposure increases the photoresponse of the as-received detectors due to the increase in unpassivated surface states. The efficiency of surface state detection is greater than that for bulk defect detection in terms of mode overlap with the defected volumes of the silicon waveguide. Detectors in all cases have a 3dB bandwidth of 7GHz.