Post on 02-Oct-2020
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CMOS-based
Single Photon
Detectors and
Potential ApplicationsDr A. Rochas, Project Leader, idQuantique SA (Switzerland)
A. Pauchard, O. Guinnard, L. Monat, and A. Matteo
2/21www.idquantique.com
Outline
- idQuantique presentation
- Motivations: limits of the present products, applications
- CMOS technology
- Single photon detector presentation
- Main features: - dead time,
- dark counts,
- afterpulsing,
- detection probability,
- timing resolution.
- Conclusion and Outlook
3/21www.idquantique.com
Company at a glance
Spun-out of University of Geneva in 2001
Strategic focus on opportunities offered by Quantum Photonics
Serve network security
and optical instrumentation markets
4/21www.idquantique.com
Optical Instrumentation
short pulse LASER source (850nm; 1.31µm; 1.55µm)
single photon counter: infrared (0.9µm to 1.6µm)
single photon counters: visible spectrum
5/21www.idquantique.com
The Present Limits
Silicon Single Photon Avalanche Diodes (Geiger Mode)Photomultiplier Tubes
High internal gain (106): single photon counting☺ ☺
Low noise level(dark counts and afterpulses)☺☺
Detection probability< 20% in the visible
Detection probability> 70% at λ = 650nm ☺
BUT:Difficult to integrate in arrays
Poor timing resolution: 500ps for PMTs, 350ps for SPADs Bulky, easily damaged
6/21www.idquantique.com
The Motivation
- a compact, solid-state,
single photon detector
- with low timing resolution
- and array integration capability.
Need for:
7/21www.idquantique.com
The Motivation
Single molecule detection: Fluorescence correlation spectroscopyor fluorescence decay time measurements
Laser ranging in space applications and telemetry
Quantum cryptography, random numbers generation
Optical fiber testing (Optical time domain reflectometry)
Laser diode characterization
8/21www.idquantique.com
Single Photon Detector
id100-20-MMFid100-20
Optical Fiber
InputFree Space
sensing part:CMOS (complementarymetal-oxide-semiconductor) chip
9/21www.idquantique.com
CMOS Technology
PC Microprocessor
- low cost fabrication- integration of electronic circuits on the same silicon chip with the SPADs- mature technology
10/21www.idquantique.com
Single Photon Detector
100µmCO OUT
GND
VDD=+5V
CMOS chip
INN
INP
VREFRq
VH
- Geiger mode: VDD + VH > Vbd
- Passive quenching
Comparator QuenchingResistor
SPAD
VDD
Ve
VREF
OUT
Time
11/21www.idquantique.com
Comparator QuenchingResistor
SPAD
100µmCO OUT
GND
VDD=+5V
CMOS chip
INN
INP
VREFRq
VH
VDD
Ve
VREF
OUT
Low C
Single Photon Detector
Time
12/21www.idquantique.com
Full Integration
Vop
npulse =C.Ve
q
Vbd
Time
IA Vop
Rq
C RdIA VVd
dead time ~ ∆trecharge α RqC
0
V
dead time < 70ns
13/21www.idquantique.com
The Noise
Unwanted counts:
- dark counts
- afterpulses
14/21www.idquantique.com
Trap-assisted
thermal generation
p+ undepleted region depletion region n-tub undepleted
region
z0 zw z
Ec
EV
TRAP
α process cleanliness: concentration and energylevel of traps
α temperature T
α excess bias voltage:probability for avalanchebreakdown
15/21www.idquantique.com
Dark Count Rate
At room temperature, for 20µm diameter:- typically < 200Hz- production yield > 90%
diameter
DCR α surface
yield
Cooling is required for larger SPADs or arrays
16/21www.idquantique.com
Afterpulsing
α process cleanliness: concentration and energy levelsof traps in the forbidden band
npulse =C.Ve
qα
Low C
p+ undepleted region depletion region n-tub undepleted
region
z0 zw z
Ec
EV
TRAP
α excess bias voltage:probability for avalanchebreakdown
17/21www.idquantique.com
Afterpulsing
Autocorrelation of a constant laser signalat a count rate of 10kHz
Becker and Hickl
Integral afterpulsing < 1%
At room temp, afterpulses in the first µs
18/21www.idquantique.com
Detection Probability
Peak in blue and decrease in the red / IR:CMOS process shallow depletion region width
junction close to the surfacep+
n
depletionregion
Photon Detection Probabilityλ=400nm, PDP=18%λ=500nm, PDP=35%λ=600nm, PDP=25%λ=700nm, PDP=20%λ=900nm, PDP=4%
19/21www.idquantique.com
Timing Resolution
p+
n
depletionregion
CMOS process: depletion region width ~1µm
40ps timing resolution (FWHM)
stable at high counting rate
Instrument Response Function at 5MHz, 2.7MHz, 62kHz
20/21www.idquantique.com
Conclusion
Technology CMOSDiameter 20µm / MMFDead Time 70ns (up to 15ns)
Detection Proba. up to 35% at 500nm
Dark Count Rate <200Hz at room T.Afterpulsing <1%
Timing Resolution 40ps FWHM / stable
id100-20
Free Space
21/21www.idquantique.com
Outlook
Large diameter single photon avalanche diodesCooling required
Development of application-oriented smart sensorsand smart sensors arrays32x32 SPADs array
smart: data processing, additional functionalities on the silicon chip
id150
by courtesy of E.Charbon-EPFL
1x10 SPADs array