Single-photon avalanche diodes in 90 nm CMOS imaging technology with sub-1 Hz median dark count rate

(SPADs) is reported in 90nm CMOS imaging technology with active diameters of 8, 4 and 2µm. An imaging-specific low doped p-well is used to create a junction with relatively high breakdown voltage (≈ 17.5 V) to reduce tunnelling and lower the DCR. The devices achieve: a peak photon detection efficiency of≈ 33% at 450nm and a spectral response comparable to 130nm SPADs; improving median DCR as the diameter is reduced of 132, 5, and 0.8 Hz, respectively, at room temperature; improving timing jitters of≈ 130,≈ 92, and≈ 78ps FWHM, respectively; and a relatively low afterpulsing of≈ 3.725% for the 4µm device.