A SPAD Depth Sensor Robust Against Ambient Light: The Importance of Pixel Scaling and Demonstration of a 2.5μm Pixel with 21.8% PDE at 940nm

A 3.06 μm Single-Photon Avalanche Diode Pixel with Embedded Metal Contact and Power Grid on Deep Trench Pixel Isolation for High-Resolution Photon Counting

“…Here, the PDE obtained in this study is not the highest value, but it is significantly higher than that of previous research [14 -16], which uses 5 µm pitch or smaller pixels, while the DCR is comparable to that of previous research using 6 µm pitch pixels [12,17,18]. The best PDE and DCR with the smallest pixel pitch (3.3 or 3 µm) were reported in [19], which were better than those of the present study. However, comparing the other pixel characteristics, as shown in Table 2, revealed that the crosstalk is lower than those of [19].…”

“…The peak PDE obtained by the green color filter is 57% with V ex = 3 V and 60% with V ex = 4 V. This can be achieved with a fill factor near 100% owing to the back-illuminated stacked structure and by optimizing the potential slope in the SPAD pixel for electron transfer [24]. The PDE under infrared light, e.g., at a wavelength of 940 nm, is much smaller than the PDE value in previous works [17][18][19]. This is due to the thinner Si thickness (2.5 µm) in our 3.06 µm pitch pixel prototype.…”

“…research can resolve this problem by achieving over 80% PDE and under 5 cps (counts per second) DCR with a 3.0 µm pitch SPAD pixel [19]. However, the crosstalk is higher compared to a 6 µm SPAD pixel [17] due to the small pitch.…”

“…We propose this idea as one of the solutions for the SPAD pixel size decreasing below 3 um pitch, despite the complexity of the fabrication process. research can resolve this problem by achieving over 80% PDE and under 5 cps (counts per second) DCR with a 3.0 µm pitch SPAD pixel [19]. However, the crosstalk is higher compared to a 6 µm SPAD pixel [17] due to the small pitch.…”

Real-time entangled photon-pair imaging towards field deployment

“…A highly scalable solution for imaging entangled photon pairs is provided by single-photon avalanche diode (SPAD) arrays, which can be affordably fabricated in standard complementary metal oxide semiconductor (CMOS) processes [22]. Recent advances include the demonstration of a 3.2 megapixel SPAD array [23], as well as a record maximum detection efficiency of 82.5% [24], indicating therefore a promising future for SPAD array cameras in high-SNR imaging of entangled photons with high spatial resolution.…”