InGaAs/InP single photon avalanche diodes with negative feedback

We have designed and fabricated various NFAD devices, and they show reasonable dark count rate and afterpulse probability at 10% PDE. These NFAD devices have great promise to reduce charge flow compared to passively quenched SPADs with hybridly integrated resistance and purely active quenched SPADs, and therefore significantly reduce afterpulse effects. Operating the NFAD is very simple compared to actively quenched free-running SPAD devices. The NFAD matrix devices have the potential of resolving photon numbers. These characteristics of NFAD devices make them attractive for many applications that require single photon sensitivity with free-running operation at SWIR wavelengths.