Repeated radiation damage and thermal annealing of avalanche photodiodes

Abstract

Avalanche photodiodes (APDs) are well-suited for single-photon detection on quantum communication satellites as they are a mature technology with high detection efficiency without requiring cryogenic cooling. They are, however, prone to significantly increased thermal noise caused by in-orbit radiation damage. Previous work demonstrated that a one-time application of thermal annealing reduces radiation-damage-induced APD thermal noise. Here we examine the effect of cyclical proton irradiation and thermal annealing. We use an accelerated testing environment which emulates a realistic two-year operating profile of a satellite in low-Earth-orbit. We show that repeated thermal annealing is effective at maintaining thermal noise of silicon APDs within a range suitable for quantum key distribution throughout the nominal mission life, and beyond. We examine two strategies—annealing at a fixed period of time, and annealing only when the thermal noise exceeds a pre-defined limit. We find both strategies exhibit similar thermal noise at end-of-life, with a slight overall advantage to annealing conditionally. We also observe that afterpulsing probability of the detector increases with cumulative proton irradiation. This knowledge helps guide design and tasking decisions for future space-borne quantum communication applications.

Enhancing the optical communication telescope laboratory to support quantum communications between earth and space

“…This is a considerable challenge, due to the adverse effects of space radiation on detector dark count rates. However, using laser or thermal annealing techniques, QEYSSat is designed to plausibly maintain the dark count rate below that required for many quantum experiments [17], [18], [19]. Since the objective of the ongoing development is to demonstrate a quantum uplink to QEYSSat as an initial verification experiment, we use this section to summarize some important parameters of the QEYSSat mission [11] that impact the ground station design.…”

Finite resource performance of small satellite-based quantum key distribution missions

“…Commencement of the QEYSSat mission in 2018 was preceded by several theoretical and experimental investigations into the mission's feasibility, both as a whole [31] and with focus on critical subsystems including pointing [32,33] and photon measurement [34,35]. Of these, one early work [36] numerically modelled the quantum optical link to establish the loss and fidelity of polarizedphoton transmission under the assumptions of the ex- pected orbital configuration and (generally conservative) atmospheric conditions.…”

Repeated γ Irradiation and Thermal Annealing via Built-In Thermo-Electric Coolers of Si Avalanche Photodiodes

“…However, the satellite method is not without problems. Satellites in LEO are exposed to radiation that can damage on-board Silicon Geiger-mode Avalanche Photodiodes (GM-APDs) [5][6][7][8][9][10], a key consequence of which is an increase in GM-APD dark count rate [8][9][10][11][12][13][14][15][16]. This is detrimental for operations involving single photons such as quantum key distribution, as the quantum bit error rate is proportional to the dark count rates.…”

“…Matters are further complicated when dopants and impurities react with vacancies and interstitials to form more complex defects with various energy levels [18]. Other GM-APD properties such as breakdown voltage, afterpulsing probability and timing jitter may also be affected by displacement damage, but prior studies have shown negligible changes [8,11,12,14,16]. Additionally, mean dark count rates may fluctuate between 2 or more levels, a phenomenon referred to as Random Telegraph Signals (RTS) [19][20][21].…”

“…Ways to mitigate radiation damage are needed. Thermal annealing has been shown to reduce dark count rate after a GM-APD has been exposed to radiation damage, with higher temperatures accelerating the process by making vacancies and interstitials more mobile and increasing the odds that they meet and annihilate each other [8,11,12,14,15,17,18]. However, current methods require heating up the entire body of the GM-APD to around 100°C for a few hours, which would demand significant energy on the cubesat.…”