Crosstalk-Free Single Photon Avalanche Photodiodes Located in a Shared Well

Vilà, A.; Figueras, E. Vilella; Alonso, O.; Diéguez, A.

doi:10.1109/led.2013.2288983

Cited by 13 publications

(9 citation statements)

References 9 publications

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“…Moreover, crosstalk can also be caused by the lateral diffusion of carriers, which also becomes a correlated noise source. In the literature, different techniques had been exploited to reduce crosstalk, such as increasing the distance between the devices, tailoring process steps (optical trenches), and gated-on mode circuitry, at the expense of smaller fill-factor [16][17][18]. Coincidence measurements were performed to evaluate the correlation between the SPADs output signals, whose time stamps were recorded by a digital oscilloscope with 10GSa/s sampling rate.…”

Section: Crosstalkmentioning

confidence: 99%

Design and characterization of a p+/n-well SPAD array in 150nm CMOS process

Pancheri

Betta

et al. 2017

Opt. Express

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This paper reports on characterization results of a single-photon avalanche diode (SPAD) array in standard CMOS 150nm technology. The array is composed by 25 (5 × 5) SPADs, based on p/n-well active junction along with a retrograde deep n-well guard ring. The square-shaped SPAD has a 10µm active diameter and 15.6µm pitch size, achieving a 39.9% array fill factor. Characterization results show a good breakdown voltage uniformity (40mV max-min) within each chip and 17mV/°C temperature coefficient. The median DCR is 0.4Hz/µm, and the afterpulsing probability is 0.85% for a dead time of 150ns at 3V excess bias voltage. The peak PDP is 31% at 450nm wavelength and a good uniformity (1.1% standard deviation) is observed for the array at 5V excess bias. The single SPADs exhibit a timing jitter of 52ps (FWHM) and 42ps (FWHM) under a 468-nm and a 831-nm laser, respectively. The crosstalk probability as a function of pixel-to-pixel distance and excess bias voltage is presented, and random telegraph signal (RTS) noise is also discussed in detail.

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Section: Crosstalkmentioning

confidence: 99%

Design and characterization of a p+/n-well SPAD array in 150nm CMOS process

Pancheri

Betta

et al. 2017

Opt. Express

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“…On the other hand, the crosstalk-probability reduction from D1 to D2 is greater than the theoretically expected rate of direct optical attenuation (1/r 2 )e -αr , where r is the distance from the emitter, and α is the absorption coefficient of silicon [9,15]. This also suggests the presence of electrical crosstalk, which is attenuated with a higher rate proportional to e -r2 [11]. The exponential shape of the crosstalk distribution in D1 indicates that electrical crosstalk has significant involvement, whereas for D2, a distinct combination of a Gaussian distribution (due to optical crosstalk) and an exponential distribution (due to electrical crosstalk) is evident.…”

Section: Noise-based Crosstalk Measurements and Resultsmentioning

confidence: 97%

“…The measurements showed a crosstalk distribution with an FWHM of ~250 ps corresponding to the combined jitter of the emitter and detector, indicating the non-existence of electrical crosstalk in the given structure with the center-to-center distance between the two measured devices exceeding 100 µm. In [11,19], Vila et al performed dark noise-generated coincidence crosstalk measurements on a very dense (67% fill factor) 5 × 1 CMOS SPAD array, counting crosstalk coincidences in minimum-2.5 ns time windows. The result emphasized the importance of the electrical crosstalk in structures with small spacing between SPADs.…”

Section: Discussionmentioning

confidence: 99%

“…A portion of these photons travel in direct and indirect optical paths, finding their way to neighboring pixels, leading to optical crosstalk [3,9]. The crosstalk may also be electrical, i.e., some of the carriers generated during the avalanche may exit the depletion region and diffuse laterally, eventually reaching the depletion region of another SPAD [10,11]. SPAD arrays, in which each pixel has its own separate terminals, have negligible electrical crosstalk because minority carriers can no longer diffuse to the nearby SPAD.…”

Section: Introductionmentioning

confidence: 99%

“…Although studies and experiments have been performed on crosstalk probability and its dependence on various parameters (distance between two devices, excess voltage, die thickness, etc [9, [11][12][13][14][15][16][17][18]. ), temporal correlation of the crosstalk coincidences in SPAD arrays has not been discussed extensively or has been reported with limited timing resolutions [11,12,17,19,20] (a more detailed review is presented in the Discussion section).…”

Section: Introductionmentioning

confidence: 99%

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Timing and probability of crosstalk in a dense CMOS SPAD array in pulsed TOF applications

Jahromi

Kostamovaara

2018

Opt. Express

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As the distance between neighboring devices in large CMOS single-photon avalanche diode (SPAD) arrays is reduced for improving the density, increased crosstalk becomes an important issue, limiting the maximum practical fill factor of the array. In this study, the temporal correlation of crosstalk events, as well as the crosstalk probability, and their dependence on parameters, such as the illumination wavelength and intensity, and the distance between SPADs, are investigated via measurement of a ~45%-fill factor CMOS SPAD array fabricated using 0.35-µm high-voltage CMOS technology. The SPADs have 24 µm × 24 µm square-shaped active areas, and all devices share a common deep-N-well cathode. On-chip time-to-digital converters with 65-ps resolution are used to measure the timing of crosstalk events in "coincidence measurements." For the crosstalk measurements, the internal noise in one SPAD is used to produce crosstalk events in the neighboring devices. The measurement results indicate both optical and electrical crosstalk with the crosstalk events, having a specific temporal distribution. The crosstalk probability in the first two adjacent pixels is found to be 0.3% and 0.01%, with a distribution having full widths at half maximum (FWHMs) of 700 and 400 ps, respectively. In pulsed time-of-flight measurements, when one SPAD is triggered with external short-pulsed (FWHM of approximately 200 ps) illumination, extra correlated noise in the adjacent SPADs added to the crosstalk noise, increasing the correlated noise considerably. This additional noise was a secondary effect of the absorbed laser photons deep in the substrate.

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