Radiation hardness properties and DCR reduction via laser annealing of InGaAs/InP SPADs for space applications

We present a theoretical and experimental study of proton radiation effects on the performance of InGaAs/InP single-photon avalanche diodes (SPADs), used in applications such as space communications and remote sensing, where single-photon detectors for the telecom-compatible near-infrared (NIR) wavelengths are required. The devices were exposed to 3 MeV protons at different fluences. At high fluences (above 10¹⁰ protons/cm²), we measured large variations in dark current, breakdown voltage, and dark count rate, while at lower fluences (below 10⁹ protons/cm²), minor variations in dark count rate, negligible variations in the dark current, and no shift in the breakdown voltage were observed. Combining experimental results with TRIM simulations, we determined the proton radiation hardness parameters, including the acceptable displacement damage dose (DDD) to avoid catastrophic failure of these types of photodiodes. Furthermore, we experimentally investigated the mitigation of the radiation damage through annealing by means of high-power lasers, and we observed a significant reduction in the dark count rate of the InGaAs/InP SPADs that were irradiated at low fluences. Our study provides important guidance on using telecom-wavelength compatible single-photon detectors in a space environment and shows that such devices are good candidates for satellite-based quantum communication nodes.