Abstract
The design, modeling, fabrication, and characterization of single-photon avalanche diode detectors with an epitaxial Ge absorption region grown directly on Si are presented. At 100 K, a single-photon detection efficiency of 4% at 1310 nm wavelength was measured with a dark count rate of ~ 6 megacounts/s, resulting in the lowest reported noise-equivalent power for a Ge-on-Si single-photon avalanche diode detector (1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-14</sup> WHz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1/2</sup> ). The first report of 1550 nm wavelength detection efficiency measurements with such a device is presented. A jitter of 300 ps was measured, and preliminary tests on after-pulsing showed only a small increase (a factor of 2) in the normalized dark count rate when the gating frequency was increased from 1 kHz to 1 MHz. These initial results suggest that optimized devices integrated on Si substrates could potentially provide performance comparable to or better than that of many commercially available discrete technologies.
Highlights
A NUMBER of emerging application areas require the technological development of efficient, low-noise, picosecond-response, single-photon detection at near-infrared wavelengths
The after-pulsing probability can be reduced by decreasing the charge passing through the device during the avalanche event by using electrical gating techniques, such that the detector is active only for a short window around the expected photon arrival time [8], [9]
Previous work demonstrated an improvement in single-photon detection efficiency (SPDE) at infrared wavelengths in a SPAD utilizing a strained SiGe/Si multiple quantum well (MQW) absorbing layer, but the necessarily low fraction of Ge and narrow thickness of MQW layer resulted in low efficiency above 1000 nm wavelength—i.e., only
Summary
A NUMBER of emerging application areas require the technological development of efficient, low-noise, picosecond-response, single-photon detection at near-infrared wavelengths. InGaAs/InP avalanche photodiodes (APDs) operated above breakdown for single-photon detection were first reported in 1996 [5], and, subsequently, custom-designed InGaAs/InP SPADs were fabricated and characterized [6].
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