Edge-coupled digital alloy AlInAsSb SPAD with high avalanche breakdown probability

Waveguide-coupled single-photon avalanche detectors (SPADs) with near-unity detection efficiencies at 1550 nm operating at moderate temperatures are a crucial component for numerous quantum optics applications. The III–V compound quaternary AlxIn1−xAsySb1−y, has material characteristics that make it attractive for low-noise linear-mode APDs and high-detection-efficiency SPADs. It can be grown on mature substrates with a high degree of flexibility with respect to absorption cutoff and can also achieve high avalanche breakdown probabilities due to its strongly asymmetric ionization coefficients. In this work, we simulate and experimentally characterize the avalanche breakdown probability of an edge-coupled, 1550 nm-illuminated AlInAsSb-based SPAD. We report avalanche breakdown probabilities greater than 85% at an over-bias of less than 2.5%.