High gain, low noise 1550 nm GaAsSb/AlGaAsSb avalanche photodiodes

We report the demonstration of a room temperature, ultra-high gain (M=278, λ=1550 nm, V=69.5 V, T=296 K) linear mode avalanche photodiode (APD) on an InP substrate using a GaAs0.5Sb0.5/Al0.85Ga0.15As0.56Sb0.44 separate absorption charge and multiplication (SACM) heterostructure. This represents a ~10× gain improvement (M=278) over commercial, state-of-the-art InGaAs/InP based APDs (M∼30) operating at 1550 nm. The excess noise factor is extremely low (F<3) at M=70 which is even lower than Si APDs. This design gives a quantum efficiency of 5935.3% at maximum gain. This SACM APD shows an extremely low-temperature breakdown sensitivity (Cbd) of ~11.83 mV/K, which is ~10× lower than equivalent InGaAs/InP commercial APDs. This demonstration opens a pathway to realize high sensitivity receiver systems at eye-safe, infrared wavelengths (1400 - 1650 nm) for a variety of applications.