Reliable InP-based Geiger-mode avalanche photodiode arrays

Arrays as large as 256 x 64 of single-photon counting avalanche photodiodes have been developed for defense applications in free-space communication and laser radar. Focal plane arrays (FPAs) sensitive to both 1.06 and 1.55 μm wavelength have been fabricated for these applications. At 240 K and 4 V overbias, the dark count rate (DCR) of 15 μm diameter devices is typically 250 Hz for 1.06 μm sensitive APDs and 1 kHz for 1.55 μm APDs. Photon detection efficiencies (PDE) at 4 V overbias are about 45% for both types of APDs. Accounting for microlens losses, the full FPA has a PDE of 30%. The reset time needed for a pixel to avoid afterpulsing at 240 K is about 3-4 μsec. These devices have been used by system groups at Lincoln Laboratory and other defense contractors for building operational systems. For these fielded systems the device reliability is a strong concern. Individual APDs as well as full arrays have been run for over 1000 hrs of accelerated testing to verify their stability. The reliability of these GM-APDs is shown to be under 10 FITs at operating temperatures of 250 K, which also corresponds to an MTTF of 17,100 yrs.