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A current assisted avalanche photodetector (CAAPD) is presented with a large detection window of 40 × 40 μm2, having a small 1-fF avalanche diode in its center. To quickly guide the photogenerated electrons to the center for avalanche multiplication, a drift field with associated majority hole current is applied across the neutral detection volume. This first type of CAAPD is fabricated in a conventional 350-nm CMOS process on a high resistive p− epi-layer. The low diode-junction capacitance can be of interest to integrated receivers. The CAAPD is characterized for its basic functionality, including the effects of lateral detection delay and gain.

A current-assisted single-photon avalanche diode (CASPAD) is presented with a large and deep absorption volume combined with a small p-n junction in its middle to perform avalanche trigger detection. The absorption volume has a drift field that serves as a guiding mechanism to the photo-generated minority carriers by directing them toward the avalanche breakdown region of the p-n junction. This drift field is created by a majority current distribution in the thick (highly-resistive) epi-layer that is present because of an applied voltage bias between the p-anode of the avalanching region and the perimeter of the detector. A first CASPAD device fabricated in 350-nm CMOS shows functional operation for NIR (785-nm) photons; absorbed in a volume of 40 × 40 × 14 μm3. The CASPAD is characterized for its photon-detection probability (PDP), timing jitter, dark-count rate (DCR), and after pulsing.

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