Germanium-on-silicon (Ge-on-Si) single photon avalanche diodes (SPADs) operating in the short-wave infrared (SWIR) have various applications such as long-range eye-safe LIDAR, quantum imaging, and quantum key distribution. These SPADs offer compatibility with Si foundries and potential cost advantages over existing InGaAs/InP devices. However, cooling is necessary to reduce dark-count rates (DCR), which limits photon absorption at 1550 nm wavelength. To address this, we propose integrating a photonic crystal (PC) nano-hole array structure on the Ge absorber layer. While this technique has shown enhanced responsivity in linear Ge detectors, its potential in Ge-on-Si SPADs remains unexplored. Our simulations consider temperature dependence and the impact of electric-field hot-spots on dark count rates. Through these simulations, we have identified means of enhancing single-photon detection efficiency (SPDE) without adversely affecting DCR. We predict significant improvements in performance, including at least a 2.5x enhancement in absorption efficiency.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Charlie McCarthy, Charlie Smith, Hannah Mowbray, Douglas J. Paul, and Ross W. Millar, "Ge-on-Si single photon avalanche diode performance enhancement with photonic crystal nano-hole arrays," Proc. SPIE 12880, Physics and Simulation of Optoelectronic Devices XXXII, 1288006 (Presented at SPIE OPTO: January 31, 2024; Published: 11 March 2024); https://doi.org/10.1117/12.3001610.