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High-rate photon counting and picosecond timing with silicon-SPAD based compact detector modules

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Andrea Giudice at Micro Photon Devices
Andrea Giudice
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Massimo Ghioni
Massimo Ghioni
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Roberto Biasi
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Roberto Biasi
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Franco Zappa
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Abstract and Figures

New detector modules exploit recent progress in the technology of silicon single-photon avalanche diodes (SPADs) and in the design of associated electronic circuits. SPAD detectors with diameter up to 100 µm, good photon detection efficiency (48% peak at 550 nm wavelength) and low dark counting rate are used in these modules. Monolithic integrated active-quenching circuits (iAQC) and fast time-pickoff circuits ensure efficient photon counting and timing, with better than 50 ps FWHM time resolution and less than 50 ps centroid shift for counting rates up to 4 Mc/s. Experimental tests of the module performance and an application example are presented.
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High
High-
-Rate Photon Counting and
Rate Photon Counting and Picosecond
Picosecond Timing
Timing
with Silicon
with Silicon-
-SPAD based Compact Detector Modules
SPAD based Compact Detector Modules
A. Giudice*, M. Ghioni°*, R. Biasi*, F.Zappa°*, and S. Cova°*
*Micro Photon Devices
Bolzano, Italy
www.micro-photon-devices.com
°Politecnico di Milano
Dipartimento di Elettronica e Informazione
Italy
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Outline
Outline
• Introduction
– Picosecond photon timing at high repetition rate
• Single Photon Avalanche Diode (SPAD)
– Performance of state-of-the-art silicon devices
• Timing electronics
– Integrated Active Quenching Circuit (i-AQC)
– Current Pick-Up Circuit
• Single Photon Timing Module
– Module performance
• Conclusions
Introduction
Introduction
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Picosecond
Picosecond photon
photon timing
timing
at high
at high repetition
repetition rate
rate
Basic goal
Æ
reduction of the acquisition time
TCPC cards working up to 4 MHz already available !
Applications
• Fluorescence Lifetime measurements
in life science and material science
• Single Molecule Spectroscopy
• Quantum Key Distribution
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
•Ultra-high Sensitivity
– High photon detection efficiency > 40 %
– Low dark counting rate < 50 c/s
•Large Active Area Diameter > 50 µm
– High collection efficiency
– Simplified optics
– Fiber pigtailing
•High Time Resolution
– Short fluorescence lifetimes < 50 ps
•Stable Instrumental Response Function (IRF)
– Minimal variation of IRF Width and Centroid at high counting rate
Detector
Timing electronics
Requirements
Requirements
Single
Single Photon
Photon Avalanche
Avalanche Diode
Diode (SPAD)
(SPAD)
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Planar Silicon
Planar Silicon SPADs
SPADs: previous devices
: previous devices
active region diameter
typically limited to ~ 20 µm
• Good QE
• Picosecond timing
• Low voltage : 15 to 40V
• Low power : cooling not necessary
• Standard Si substrate
•COMPATIBLE with array detector
and integrated circuits
• Robust and reliable
• Low-cost
• Dark counting rate increase
with active area steeper than linear
A.Lacaita, M.Ghioni, S.Cova, Electron.Lett. 25, 841 (1989)
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Planar Silicon
Planar Silicon SPADs
SPADs:
: present
present devices
devices
–Active area diameter up to 100 µm
–Dark counting rate scales linearly with active area
–35 ps FWHM time resolution with 100µm device
–Time resolution independent of diameter
Planar SPADs
SPADs with:
with:
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Breakdown
Breakdown Voltage
Voltage
4’’ Silicon wafer:
• Mean Value:28.7V
• Total Spread: 2.3V
–Good process control
– Good performance uniformity
• Photon detection efficiency
• Series resistance
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Dark
Dark Counting
Counting Rate
Rate
Dark Counting Rate (DCR)
• Avalanche pulses triggered by
thermally generated carriers
• Detector Shot Noise
• Equivalent to the dark current
in PINs and APDs
10%
40%
65%
Yield
4000100
150050
30020
DCR
(c/s)
Diameter
(µm)
Comparison of SPAD devices
with different diameter
Tested @ room temp. (23°C) with 5V overvoltage
•DCR of good devices scales linearly with area
• Yield of good devices decreases with the area,
likely due to extended defects
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
DCR
DCR vs
vs Temperature
Temperature
Combined Physical Effects in DCR
• Field enhanced SRH generation @ higher T
• Band to band tunneling @ lower T
Practical Exploitation of DCR vs T :
Peltier cooling to -20°C
– is simple / cheap / rugged
– reduces DCR by a factor of 30
Fast timing
Fast timing electronics
electronics
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
F.Zappa, S.Cova, M.Ghioni, US patent 6,541,752 B2, 2003 (prior. March 9, 2000)
iAQC
iAQC: integrated Active Quenching Circuit
: integrated Active Quenching Circuit
Practical advantages
• Miniaturization Æmini-module detectors
• Low-Power Consumption Æportable modules
• Rugged and Reliable
Plus improved performance
• Reduced Capacitance
• ImprovedPhotonTiming
• Reduced Avalanche Charge
• Reduced Afterpulsing
• Reduced Photoemission Æreduced crosstalk
in arrays
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
0 40 80 120 160 200
Threshold
v
ol
t
age (mV)
25
75
125
0
50
100
150
Time resolution FWHM (ps)
Signal pick
Signal pick-
-up for
up for improved
improved photon
photon-
-timing
timing
• Avalanche current sensing
at very low level (< 100 µA)
• Can be added to any AQC
S.Cova, M.Ghioni, F.Zappa, US patent No. 6,384,663 B2, 2002 (prior. March 9, 2000)
50 µm active
area diameter
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Formerly LARGE area detectors
DID NOT achieve highest time resolution
Now by using the current pick-up circuit and
sensing the avalanche current
at very low level (< 100 µA):
– FWHM practically independent of the
detector diameter
–35ps FWHM checked for 100µm device
at room temperature
0 400 800 1200 1600
Time (ps)
Counts
10
0
1
2
3
4
FWHM = 35 ps
FW1/100M = 370 ps
10
10
10
10
Recent advancement
35100 3450 3220
Time Resolution
FWHM (ps)
Active Area
Diameter
(µm)
35100 3450 3220
Time Resolution
FWHM (ps)
Active Area
Diameter
(µm)
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Single Photon Counting / Timing Module
Single Photon Counting / Timing Module
Planar SPAD detector
Planar SPAD detector
+
+ iAQC
iAQC
Compact and user-friendly
Single Photon
Counting/Timing Module
+ Timing pick
+ Timing pick-
-up network
up network
Single
Single Photon
Photon Timing
Timing Module
Module
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
¾Easy to use
¾Robust and Rugged
¾Low power consumption
¾Low cost
¾5V power supply
¾GATE input
Size
5cm x 4 cm x 8cm
Photon Detection Module
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
At 5V overvoltage
•Max PDE = 48% @530nm
•PDE >30% over all the visible
range
PDE = QE x η
- QE = quantum efficiency
-η= avalanche triggering probability
Photon
Photon Detection
Detection Efficiency
Efficiency
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
400 450 500 550 600 650 700 750 800 850 900 950 1000
Wavelength (nm)
Photon Detection Efficiency
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
IRF
IRF stability
stability
100
1000
10000
2 2.2 2.4 2.6 2.8 3 3.2
Time (ns)
Counts (A.U.)
8.5kc/s
340kc/s
2.2Mc/s
λ
λ= 820 nm
= 820 nm
20
40
60
80
100
1 10 100 1000 10000
Background counts
Picoseconds
1k 10k 100k 1M 10M
0
25
50
75
100
1 10 100 1000 10000
Back
g
round counts
Picoseconds
1k 10k 100k 1M 10M
FWHM value
Centroid shift
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Afterpulsing
Afterpulsing Effect
Effect
Courtesy by Picoquant GmbH
•50 µm detector
• Time Tagged
Time Resolved (TTTR) method
• Afterpulsing negligible after 1 µs
• Total afterpulsing probability < 1%
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
1
10
100
1000
10000
100000
0 5 10 15 20 25 30 35
Time (ns)
Counts
2.8 ns
FWHM=100ps
• Synchrotron emission
of light pulses
@ 630 nm wavelength
• Mean photon counting
rate ~ 1 Mc/s
Onset of electron bunch train in a synchrotron
measured by TCPC with SPTM Module
Single-Photon Workshop 2005
A. Giudice et al
National Physical Laboratory ,Teddington, UK, 24 - 26 October 2005
Micro Photon Devices, Bolzano, Italy
Conclusions
Conclusions
• Planar SPAD devices with improved technology provide
– Active area diameter up to 100 µm
– Low dark counting rate, scaling with detector area
– Low afterpulsing effect
• New time pick-up circuit produces
– Time resolution independent of active area diameter
– 35 ps FWHM time resolution with 100 µm SPAD @RT
– stable IRF up to very high photon counting rates
• Single-Photon detector modules grant overall performance
– adequate to accurate picosecond timing
– up to multi-MHz photon rate
... Single-channel SPADs and other SPAD-based sensors such as silicon photomultipliers (SiPMs) are commercially available either in dedicated technologies [4], [5] or as a standard library cell within some CMOS technologies [6]. They are used in the field of radiation instrumentation [7], [8], light detection and ranging [9] and quantum communication [10]. ...
... The dark count rate and afterpulsing can also be tested with the die-level setup. However, DCR and AP require a large sample to properly infer the population distributions [4]. To this end, the wafer-level configuration is more appropriate. ...
... 5 ------ The median V BD of Fig. 17 is 24.3 V with a standard deviation of 0.5%. The measurement is done at 18±2 o C. The V BD result of Fig. 17 is typical with respect to previously reported V BD statistics for commercial single cell SPAD [4] and for commercial SiPMs [18], [29]. The wafer-scale patterns/regions visible on the contour plot could highlight slight non-uniformities during processing (e.g. ...
Wafer-Level Characterization and Monitoring Platform for Single-Photon Avalanche Diodes
Article
Full-text available
  • Jan 2024
When developing a technology based on single-photon avalanche diodes (SPADs), the SPAD characterization is mandatory to debug, optimize and monitor the microfabrication process. This is especially true for the development of SPAD arrays 3D integrated with CMOS readout electronics, where SPAD testing is required to qualify the process, independently from the final CMOS readout circuit. This work reports on a characterization and monitoring platform dedicated to SPAD testing at die and wafer level, in the context of a 3D SPAD technology development. The platform relies on a dedicated integrated circuit made in a standard CMOS technology and used in different configurations from a prototype printed circuit board (die-level testing) to active probe cards (wafer-level mapping). The platform gives full access to SPAD characteristics in Geiger mode such as the dark noise, photon detection efficiency and timing resolution. The integrated circuit and its configuration are described in detail as well as results obtained on different SPAD test structures. In particular, the dark count rate mapping demonstrates the benefits of testing SPADs at wafer level at the R&D stage.
View
... Single-channel SPADs and other SPAD-based sensors such as silicon photomultipliers (SiPMs) are commercially available either in dedicated technologies [4], [5] or as a standard library cell within some CMOS technologies [6]. They are used in the field of radiation instrumentation [7], [8], light detection and ranging [9] and quantum communication [10]. ...
... The dark count rate and afterpulsing can also be tested with the die-level setup. However, DCR and AP require a large sample to properly infer the population distributions [4]. To this end, the wafer-level configuration is more appropriate. ...
... The median V BD is 24.3 V with a standard deviation of 0.5%. The measurement is done at 18±2 o C. The V BD result of Fig. 16 -0.7 6.6 6.9 -1. is typical with respect to previously reported V BD statistics for commercial single cell SPAD [4] and for commercial SiPMs [17], [27]. The wafer-scale patterns/regions visible on the contour plot could highlight slight non-uniformities during processing (e.g. ...
Wafer-level Characterization and Monitoring Platform for Single-Photon Avalanche Diodes
Preprint
Full-text available
  • Oct 2023
p>When developing a technology based on single-photon avalanche diodes (SPADs), the SPAD characterization is mandatory to debug, optimize and monitor the microfabrication process. This is especially true for the development of SPAD arrays 3D integrated with CMOS readout electronics, where SPAD testing is required to qualify the process, independently from the final CMOS readout circuit. This work reports on a characterization and monitoring platform dedicated to SPAD testing at die and wafer level, in the context of a 3D SPAD technology development. The platform relies on a dedicated integrated circuit made in a standard CMOS technology and used in different configurations from a prototype printed circuit board (die-level testing) to active probe cards (wafer-level mapping). The platform gives full access to SPAD characteristics in Geiger mode such as the dark noise, photon detection efficiency and timing resolution. The integrated circuit and its configuration are described in detail as well as results obtained on different SPAD test structures. In particular, the dark count rate mapping demonstrates the benefits of testing SPADs at wafer level at the R&D stage.</p
View
... Single-channel SPADs and other SPAD-based sensors such as silicon photomultipliers (SiPMs) are commercially available either in dedicated technologies [4], [5] or as a standard library cell within some CMOS technologies [6]. They are used in the field of radiation instrumentation [7], [8], light detection and ranging [9] and quantum communication [10]. ...
... The dark count rate and afterpulsing can also be tested with the die-level setup. However, DCR and AP require a large sample to properly infer the population distributions [4]. To this end, the wafer-level configuration is more appropriate. ...
... The median V BD is 24.3 V with a standard deviation of 0.5%. The measurement is done at 18±2 o C. The V BD result of Fig. 16 -0.7 6.6 6.9 -1. is typical with respect to previously reported V BD statistics for commercial single cell SPAD [4] and for commercial SiPMs [17], [27]. The wafer-scale patterns/regions visible on the contour plot could highlight slight non-uniformities during processing (e.g. ...
Wafer-level Characterization and Monitoring Platform for Single-Photon Avalanche Diodes
Preprint
Full-text available
  • Oct 2023
p>When developing a technology based on single-photon avalanche diodes (SPADs), the SPAD characterization is mandatory to debug, optimize and monitor the microfabrication process. This is especially true for the development of SPAD arrays 3D integrated with CMOS readout electronics, where SPAD testing is required to qualify the process, independently from the final CMOS readout circuit. This work reports on a characterization and monitoring platform dedicated to SPAD testing at die and wafer level, in the context of a 3D SPAD technology development. The platform relies on a dedicated integrated circuit made in a standard CMOS technology and used in different configurations from a prototype printed circuit board (die-level testing) to active probe cards (wafer-level mapping). The platform gives full access to SPAD characteristics in Geiger mode such as the dark noise, photon detection efficiency and timing resolution. The integrated circuit and its configuration are described in detail as well as results obtained on different SPAD test structures. In particular, the dark count rate mapping demonstrates the benefits of testing SPADs at wafer level at the R&D stage.</p
View
... The PDC has an 8 × 8 SPAD [15,16] array in addition to the electronics on-chip (see Figure 1). This implementation is suboptimal because the 65 nm SPADs, although having a good timing resolution (7.8 ps FWHM SPTR at 410 nm wavelength [17]), suffer from low photon detection efficiency (7% at 410 nm in this work) and high noise (680 kcps average per SPAD). ...
... B-SPADs: Single-photon avalanche diodes are photodiodes that are reverse biased beyond their breakdown voltage [15,16,18]. Because of this high electric field, an incoming single photon causes an avalanche current, which is detected and stopped by the quenching circuit. ...
Towards a Multi-Pixel Photon-to-Digital Converter for Time-Bin Quantum Key Distribution
Article
Full-text available
  • Mar 2023
  • SENSORS-BASEL
We present an integrated single-photon detection device custom designed for quantum key distribution (QKD) with time-bin encoded single photons. We implemented and demonstrated a prototype photon-to-digital converter (PDC) that integrates an 8 × 8 single-photon avalanche diode (SPAD) array with on-chip digital signal processing built in TSMC 65 nm CMOS. The prototype SPADs are used to validate the QKD functionalities with an array of time-to-digital converters (TDCs) to timestamp and process the photon detection events. The PDC uses window gating to reject noise counts and on-chip processing to sort the photon detections into respective time-bins. The PDC prototype achieved a 22.7 ps RMS timing resolution and demonstrated operation in a time-bin setup with 158 ps time-bins at an optical wavelength of 410 nm. This PDC can therefore be an important building block for a QKD receiver and enables compact and robust time-bin QKD systems with imaging detectors.
View
... In reference [7], a double-epitaxy SPAD was presented. The planar structure (see figure 1.4) consists of an n+/p+ junction situated in a p-type epitaxial layer. ...
... Cross section of a double-epitaxy SPAD (not to scale)[7]. ...
View
... This is independent of any emitting laser characteristics but may change with detector technology such as the cross-sectional area of the sensor. For single element detectors, a widely used commercial SPAD (the MPD's PDM series) is able to provide a dark count rate (DCR) of <50 cps (counts per second) [46]. For large-scale array detectors, a 192 × 128 CMOS SPAD array with 25 cps median DCR/pixel has been reported in 2019 [47]. ...
Assessing Novel Lidar Modalities for Maximizing Coverage of a Spaceborne System through the Use of Diode Lasers
Article
Full-text available
  • May 2022
Current satellite lidars have sparse spatial coverage, leading to uncertainty from sampling. This complicates robust change detection and does not allow applications that require continuous coverage. One potential way to increase lidar sampling density is to use more efficient lasers. All current spaceborne lidars use solid-state lasers with a limited efficiency of 5–8%. In this paper, we investigate the potential for using diode lasers, with their higher efficiencies, as an alternative. Diode lasers have reported efficiencies of about 25% and are much smaller and lighter than solid-state lasers. However, they can only emit good beam quality at lower peak powers, which has so far prevented them from being used in spaceborne lidar applications. In this paper, we assess whether the novel lidar modalities necessitated by these lower peak powers are suitable for satellite lidar, determined by whether they can match the design performance of GEDI by being able to accurately measure ground elevation through 98% canopy cover, referred to as having “98% beam sensitivity”. Through this, we show that a diode laser can be operated in pulse train or pulse compressed lidar (PCL) mode from space, using a photon-counting detector. In the best case scenario, this setup requires a detected energy of Edet=0.027fJ to achieve a beam sensitivity of 98%, which is less than the 0.28fJ required by a full-waveform solid-state lidar instrument, exemplified by GEDI. When also accounting for the higher laser and detector efficiency, the diode laser in pulse train mode requires similar shot energy as a photon counting solid-state laser such as ICESat-2 which along with the higher laser efficiency could result in a doubling of coverage. We conclude that there is a clear opportunity for diode lasers to be used in spaceborne lidars, potentially allowing wider coverage through their higher efficiencies.
View
... 21 Another important benefit of short wavelength operation is the widespread availability of efficient single photon avalanche diodes (SPADs) with very high timing resolution at wavelengths near 550 nm. These SPADs with high efficiency $50%, but more importantly, with timing jitter as low as 35 ps, 22,23 provide a jitter much lower than the typical timing jitter between 300 and 1500 ps for wavelengths > 650 nm. 24 Both the detection efficiency and the timing jitter are of great importance toward practical applications: on the one hand, detection efficiency leads to a higher generated key rate and faster image acquisition. ...
Visible-wavelength polarization-entangled photon source for quantum communication and imaging
Article
Full-text available
  • Feb 2022
  • APPL PHYS LETT
We present a polarization-entangled photon pair source operating in the visible light range around 532 nm. Employing a collinear crossed-crystal scheme with type-I degenerate phase matching in barium borate (BBO), our source achieves a brightness of 9.5 k pairs/s/mW and a quantum state fidelity of 98.3%, making it a candidate for integration in microscopes and make use of the advantages of mid-visible optimized single-photon detection technologies. In order to study potential applications, we present a trade-off between source brightness and polarization entanglement visibility and propose use cases for different filtering configurations of the source, capable of a brightness up to 1.23 M pairs/s/mW.
View
View
Implémentation de diode à avalanche à photon unique (SPAD) dans une technologie CMOS FD-SOI 28nm
Thesis
  • Dec 2021
L'objectif de cette thèse concerne la simulation, la conception et la caractérisation de nouvelles structures de diodes à avalanche à photon unique (Single Photon Avalanche Diode - SPAD) implémentées dans la technologie CMOS FD-SOI (Fully Depleted Silicon On Insulator) 28nm de STMicroelectronics. Les photodétecteurs SPAD présentent une grande sensibilité de détection (associée à un temps de réponse très court) qui fait d’eux d’excellents candidats pour la mesure du temps de vol (Time Of Flight – ToF) dans des applications de télémétrie, de reconnaissance faciale et de LIDAR (Light Detection And Ranging) pour les voitures autonomes. L’intégration de la SPAD en CMOS FD-SOI permet de créer un pixel intrinsèquement 3D, i) en incorporant la SPAD au niveau de la jonction PW (P-Well) / DNW (Deep N-Well) dans le silicium bulk sous l’oxyde enterré (BOX) et ii) en utilisant le film silicium situé au-dessus du BOX pour intégrer l'électronique associée au détecteur (circuits d'étouffement et d'adressage), tout en optimisant le facteur de remplissage avec une approche BSI (back side illumination). Les SPAD réalisées dans la technologie native (avec respect des règles de dessin) ont mis en évidence plusieurs points faibles : un DCR (Dark Count Rate) élevé pour des tensions d'excès faibles (500Hz/µm2 à Vex = 0.5V pour une tension de claquage de 9.5V) ainsi qu'un claquage prédominant sur la périphérie de la zone active. Dans ce contexte, les travaux présentés dans cette thèse ont porté sur l'optimisation des performances électriques de la SPAD FD-SOI par des modifications de la structure respectant ou non le procédé de fabrication : adaptation des conditions d’implantation du caisson profond DNW, remaniement des tranchées STI (Shallow Trench Isolation) etc. Les structures SPAD-FD-SOI ainsi optimisées ont démontré expérimentalement un bien meilleur niveau de DCR (17Hz/µm2 à Vex = 1V pour une tension de claquage de 15.8V). Des caractérisations électro-optiques préliminaires ont été réalisées avec une probabilité de détection des photons de l’ordre de 7% à Vex = 1V et une longueur d’onde de 650nm. Même si ces travaux n’ont pas permis d’atteindre les performances des SPAD les plus performantes de l’état de l’art, ils ont exploré de nombreuses voies d’optimisation, certaines conduisant à une amélioration significative des performances des SPAD réalisées dans cette technologie. La poursuite de ces travaux (association de ces structures SPAD FD-SOI optimisées avec une électronique intégrée performante, amincissement des dispositifs pour opérer avec un éclairage par la face arrière etc.) devrait permettre de réaliser des pixels SPAD intrinsèquement 3D (sans recours à du collage de wafers) très performants dans le proche infrarouge pour les applications d’imagerie 3D embarquées.
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Fluorescence-encoded Infrared (FEIR) spectroscopy is a vibrational spectroscopy technique that has recently demonstrated the capability of single-molecule sensitivity in solution without near-field enhancement. This work explores the practical experimental factors that are required for successful FEIR measurements in both the single-molecule and bulk regimes. We investigate the role of resonance conditions by performing measurements on a series of coumarin fluorophores of varying electronic transition frequencies. To analyze variations in signal strength and signal to background between molecules, we introduce an FEIR brightness metric that normalizes out measurement-specific parameters. We find that the effect of the resonance condition on FEIR brightness can be reasonably well described by the electronic absorption spectrum. We discuss strategies for optimizing detection quality and sensitivity in bulk and single-molecule experiments.
View
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Recent advances in single-molecule detection and single-molecule spectroscopy at room temperature by laser-induced fluorescence offer new tools for the study of individual macromolecules under physiological conditions. These tools relay conformational states, conformational dynamics, and activity of single biological molecules to physical observables, unmasked by ensemble averaging. Distributions and time trajectories of these observables can therefore be measured during a reaction without the impossible need to synchronize all the molecules in the ensemble. The progress in applying these tools to biological studies with the use of fluorophores that are site-specifically attached to macromolecules is reviewed.
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Full-text available
  • Apr 1996
Avalanche photodiodes, which operate above the breakdown voltage in Geiger mode connected with avalanche-quenching circuits, can be used to detect single photons and are therefore called singlephoton avalanche diodes SPAD's. Circuit configurations suitable for this operation mode are critically analyzed and their relative merits in photon counting and timing applications are assessed. Simple passive-quenching circuits (PQC's), which are useful for SPAD device testing and selection, have fairly limited application. Suitably designed active-quenching circuits (AQC's) make it possible to exploit the best performance of SPAD's. Thick silicon SPAD's that operate at high voltages (250-450 V) have photon detection efficiency higher than 50% from 540- to 850-nm wavelength and still ~3% at 1064 nm. Thin silicon SPAD's that operate at low voltages (10-50 V) have 45% efficiency at 500 nm, declining to 10% at 830 nm and to as little as 0.1% at 1064 nm. The time resolution achieved in photon timing is 20 ps FWHM with thin SPAD's; it ranges from 350 to 150 ps FWHM with thick SPAD's. The achieved minimum counting dead time and maximum counting rate are 40 ns and 10 Mcps with thick silicon SPAD's, 10 ns and 40 Mcps with thin SPAD's. Germanium and III-V compound semiconductor SPAD's extend the range of photon-counting techniques in the near-infrared region to at least 1600-nm wavelength.
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Measuring Conformational Dynamics of Biomolecules by Single Molecule Fluorescence Spectroscopy
Article
Full-text available
  • Oct 2000
  • Nat Struct Biol
Dynamic structural changes of macromolecules undergoing biochemical reactions can be studied using novel single molecule spectroscopy tools. Recent advances in applying such distance and orientation molecular rulers to biological systems are reviewed, and future prospects and challenges are discussed.
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Protein Conformational Dynamics Probed by Single-Molecule Electron Transfer
Article
Full-text available
  • Nov 2003
  • SCIENCE
Electron transfer is used as a probe for angstrom-scale structural changes in single protein molecules. In a flavin reductase, the fluorescence of flavin is quenched by a nearby tyrosine residue by means of photo-induced electron transfer. By probing the fluorescence lifetime of the single flavin on a photon-by-photon basis, we were able to observe the variation of flavin-tyrosine distance over time. We could then determine the potential of mean force between the flavin and the tyrosine, and a correlation analysis revealed conformational fluctuation at multiple time scales spanning from hundreds of microseconds to seconds. This phenomenon suggests the existence of multiple interconverting conformers related to the fluctuating catalytic reactivity.
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35 ps time resolution at room temperature with large area single photon avalanche diodes
Article
Full-text available
  • Apr 2005
It is demonstrated that remarkable timing performance is achievable with large area single photon avalanche diodes (SPADs), provided that the avalanche current is sensed at very low level, when the multiplication process is still confined within a small area around the photon absorption point. By employing a suitable current pick-up circuit, an unprecedented time resolution of 35 ps was obtained with a 100 μm active area diameter SPAD.
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Advanced Time-Correlated Single Photon Counting Techniques
Book
  • Jan 2005
Optical Signal Recording.- Overview of Photon Counting Techniques.- Multidimensional TCSPC Techniques.- Building Blocks of Advanced TCSPC Devices.- Application of Modern TCSPC Techniques.- Detectors for Photon Counting.- Practice of TCSPC Experiments.- Final Remarks.- References.
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Monitoring Conformational Dynamics of a Single Molecule by Selective Fluorescence Spectroscopy
Article
  • Mar 1998
A recently developed, real-time spectroscopic technique, burst-integrated fluorescence lifetime (BIFL), is shown to be well suited for monitoring the individual molecular conformational dynamics of a single molecule diffusing through the microscopic, open measurement volume (≈10 fl) of a confocal epi-illuminated set-up. In a highly diluted aqueous solution of 20-mer oligonucleotide strand of DNA duplex labeled with the environment-sensitive fluorescent dye tetramethylrhodamine (TMR), fluorescence bursts indicating traces of individual molecules are registered and further subjected to selective burst analysis. The two-dimensional BIFL data allow the identification and detection of different temporally resolved conformational states. A complementary autocorrelation analysis was performed on the time-dependent fluctuations in fluorescence lifetime and intensity. The consistent results strongly support the hypothesized three-state model of the conformational dynamics of the TMR–DNA duplex with a polar, a nonpolar, and a quenching environment of TMR.
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Analyzing single protein molecules using optical methods
Article
  • Sep 2001
  • CURR OPIN BIOTECH
Studies on single protein molecules have advanced from mere proofs of principle to insightful investigations of otherwise inaccessible biological phenomena. Recent studies predict a tremendous number of possible future applications. The long-term vision of biologists to watch single molecular processes in real time by peering into a cell with three-dimensional resolution might finally be realized. Another fascinating perspective is the identification and selection of single favorable variants from complex libraries of diverse biomolecules.
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Probing Single Molecule Dynamics
Article
  • Aug 1994
The room temperature dynamics of single sulforhodamine 101 molecules dispersed on a glass surface are investigated on two different time scales with near-field optics. On the 10(-2)- to 10(2)-second time scale, intensity fluctuations in the emission from single molecules are examined with polarization measurements, providing insight into their spectroscopic properties. On the nanosecond time scale, the fluorescence lifetimes of single molecules are measured, and their excited-state energy transfer to the aluminum coating of the near-field probe is characterized. A movie of the time-resolved emission demonstrates the feasibility of fluorescence lifetime imaging with single molecule sensitivity, picosecond temporal resolution, and a spatial resolving power beyond the diffraction limit.
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A process and deep level evaluation tool: afterpulsing in avalanche junctions
Conference Paper
  • Oct 2003
A technique for a separate experimental characterization of generation centres and deep levels in junctions is presented. The test device required is a small junction that operates in Geiger-mode above the breakdown level. Time-resolved measurements of correlated afterpulsing effects are exploited for separating noise contributions due to generation centres and to carrier trapping in deep levels. Release transients down to the nanosecond range are characterised and lifetimes of individual trap levels are measured. Experimental data for devices fabricated with different technologies illustrate the information gained about the efficiency of the fabrication process and in particular of gettering steps.
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