Afterpulsing in Ge-on-Si Single-Photon Avalanche Diodes
Xin Yi, Zoë M. Greener, Fiona Fleming, Jarosław Kirdoda, Derek C. S. Dumas, Lisa Saalbach, Dave Muir, Lourdes Ferre-Llin, Ross W. Millar, Douglas J. Paul, Gerald S. Buller
Abstract
In this letter, we investigate afterpulsing in 26 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100~\mu \text{m}$ </tex-math></inline-formula> diameter planar geometry Ge-on-Si single-photon avalanche diode (SPAD) detectors, by use of the double detector gating method with a gate width of 50 ns. Ge-on-Si SPADs were found to exhibit a 1% afterpulsing probability at a delay time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$200~\mu \text{s}$ </tex-math></inline-formula> and temperature of 78 K, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$130~\mu \text{s}$ </tex-math></inline-formula> at a temperature of 150 K. These delay times were measured with an excess bias of 3.5% applied, which corresponded to a single-photon detection efficiency of 15% at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.31~\mu \text{m}$ </tex-math></inline-formula> . We demonstrate that reducing the detector diameter can also be an effective way to restrict afterpulsing in this material system.