hgcdte avalanche photodiodes development at cea/leti-minatec
DESCRIPTION
2009. HgCdTe avalanche photodiodes development at CEA/Leti-Minatec. Johan Rothman CEA: L. Mollard, S. Bisotto Sofradir: X. Lefoule, F. Pistone. Outline. HgCdTe e-APD development in France Why HgCdTe e-APDs? Performance Applications HgCdTe e-APDs for photon-counting - PowerPoint PPT PresentationTRANSCRIPT
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
1
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
HgCdTe avalanche photodiodes development at CEA/Leti-MinatecJohan Rothman
CEA: L. Mollard, S. Bisotto
Sofradir: X. Lefoule, F. Pistone
2009
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
2
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
Outline
HgCdTe e-APD development in FranceWhy HgCdTe e-APDs?
PerformanceApplications
HgCdTe e-APDs for photon-countingFocal plane array resultsHgCdTe e-APD road map at LETI-
Minatec and SofradirConclusion/perspectives
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
3
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
HgCdTe e-APD development in France
CEA/LETI E-APD technology
and design Epitaxy, µ-tech.
E-APD physics and test Response time Multiplication process
(gain, noise) Sensitivity limits
ROIC design EO FPA test
Sofradir ROIC design EO FPA test E-APD FPA
industrialisation Fab etc..
ONERA E-APD physics
Multiplication process (gain, noise)
EO FPA test
Astro-physics labs LAOG ( Grenoble) and
LAM (Marseille) Adaptiv optics, fringe
tracking Photon-counting imaging
e-APDs
Detector lab and fab
System labs
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
4
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
The photodiode: an ideal light detector?
High timing resolutionQE100% i.e. no loss of informationHigh Sensitivity
Dark currents can be lower than 1 electron/sLimited by proximity-electronics (PE) noise
Can be reduced by amplified photo detection!
M
M x Photo-current
PE noise
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
5
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
APDs Advantages vs. Photo-multipliers or amplified-CCD
High Quantum efficiency 100% All detection-modes are possible
Photon-counting Real time measurement of the flux f(t) at high speed Integration (standard imaging operation) Non-linear geiger mode (avalanche breakdown)
Small and fast Compatible with imaging and telecom applications
…but furious (other than HgCdTe-APDs…) Multiplication of both electrons and holes in Si and III-V
material APDs Gain is strongly dependent on junction profile High
dispersion (not good for imaging) Strong degradation of the SNR: F=SNRSNL/SNRout>2-5 at
M>10 Response time is slowed down at high gain Limited
gain- Band-Width product < 340GHz (Intel record, Nature Photonics, 3, 2008)
After pulsing probability >0 (photon counting) Dead time (photon counting)
dtttint
t
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
6
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
Exclusive electron multiplication in HgCdTe APDs
Exponential gain without avalanche break down (Beck,DRS, 2001) Exclusive electron multiplication
Felectric~1-1.2 (DRS, SELEX, LETI, BAE, TELEDYNE) Response time independent of gain GBW>16THz (LETI) Low gain dispersion Noise equivalent input counts Neq_in< 10 000 e/s (LETI, DRS)
Stable up to M>5000 (LETI APD Record, 2006)PLUS all the standard properties of HgCdTe
High quantum efficiency (close to 100% internal QE) Detect wavelengths from visible to IR (with QE~100%)Low operating temperatures due to small Eg
1.0
10.0
100.0
1000.0
10000.0
-14.0 -13.0 -12.0 -11.0 -10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0
Bias (V)
Ga
inG
ain
M=
I/I C
C
HgCdTe e-APDc=5µm, T=80K
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
7
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
A new horizon of applications from visible to IR wavelengths with MCT e-APDs :(M>1000, F~1, Neq_in<10 000 e/s)
Photon counting Quantum optics
Physics, astronomy, quantum cryptography Imaging in Astronomy, biomedical applications, high-energy physics
Astronomy : higher order correlation functions! Real-time measurements
Telecommunications Time resolved Raman and Fluorescence spectroscopy, Doppler effect
Environmental surveillance, element recognition Real-time dynamics observations
Integration (Imaging FPAs) Active laser assisted imaging
Long range identification, safe planetary landing (NASA), bio-medical (fluorescence imaging), observation through semi transparent surfaces
Passive amplified imaging Low flux applications ; hyper spectral imaging, wave front
detection for astronomy, high dynamic range The geiger modes is not (yet) possible due to the absence
of avalanche break-down threshold
dtttint
t
This talk (1)
This talk (2)
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
8
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
Performance optimization of HgCdTe e-APDs?
MW (c=4.2-5µm) e-APD performances:M>100, F=1.2, Ieq_in~10000 e/s, tresp~2 ns, Top<100K
Application Photon countingM, F ok
Passive amplified imagingM, F, tresp ok
Critical parameter
1. Reduce tresp : <100 psReduce Ieq_in : <1000 e/s(Operability)
1. Reduce Ieq_in :
< 1000 e/s2. Increase Top
(Operability)
This talk E-APD gain (F~1) for photon countingResponse time limits (jitter)
Impact of xCd:
Gain, F, dark current(Diodes and FPAs)
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
9
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
Photon counting
Counter : Direct pixel digitalization Read-out noise supression High dynamic range (>16 bit) High frame-rate Dark-current thresholding
Timer :Estimation of the time of arrival of the photons 3D imaging Quantum optics and imaging
higher order photon correlation functions
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
10
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0 100 200 300 400 500 600 700 800 900
Output counts
pro
ba
bil
ity
de
ns
ity
Exclusive electron multiplication for Linear mode proportional photon counting
Low F Proportional photon counting Distinguish the number of photons that arrives simultaneously in the
depletion layer (not possible in GM-APDs) Reduce after-pulsing effects 0% (GM –APDs ~10%)
High order temporal correlation function A new window for astronomy !
No quenching high repetition rates >GHz is possible (GM-APDs ~ 10MHz)
1 photon2 photons
Output count probability distribution for <M>=300 and F=1.04
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
11
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0 100 200 300 400 500 600 700 800 900
Output counts
pro
ba
bil
ity
de
ns
ity
Exclusive electron multiplication for Linear mode proportional photon counting
Low F Proportional photon counting Reduce after-pulsing effects (GM –APDs ~10%) No quenching high repition rate >GHz is possible (GM-APDs ~
10MHz) Low F Discrimination of non-amplified dark current Low DCR
Depends on the distribution of the dark current generation Homogeneous distribution <M>dark=52 for Mdiff=300
1 photon2 photons
Output count probability distribution for <M>=300 and F=1.04
Distributed dark-current generation p i n
DC generation
diffdiff
diff
gencontdark MM
MM
11
ln__
<M>dark
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
12
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
Response time optimization in APDs
n-
n+
p
Depletion layer = mutliplication region
E
Collection of minority electrons Diffusion ~ 1-5 ns1
Drift (xCd gradient) Vd of e in p type HgCdTe 50-100 ps jitter3
Transit time of e and h Vd(E) : th=10-50ps GBW limit ~20THz (MW)1,2
RC charge evacuation ~ 10-50 ps Ultimate photon counting timing resolution <100ps!
Collection of minority electrons
Transit time of e and h
RC charge evacuation
1. G. Perrais et al. JEM, 37, 20082. G. Perrais et al. JEM, 38, 20093. J. Rothman et al. to be published, JEM, 40 (2010)
Response time jitter limits the timing precision
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
13
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
CTIA coupled one-shot TOF+R imaging (3D) Pulse detection in C10 (1)
Sample time sweep TOF (2) Switch to integrate the total light pulse in C20 (3)
+
-
Vth
C3D
Track & Hold
Vref
C2D
Lock
Time base(analog voltage ramp)
+
-
OTAN1
N2 N3
Iin
Return intensity
T.O.F.
Pixel outputs :
RESET
Precharge
"Advanced pixel design for infrared 3D LADAR imaging"F. Guellec, SPIE DSS, 6940-84
First move towards photon counting (2008): Active 3D Imaging 4x10 test FPA, 40µm pitch
Sequential and spatial TOF<2ns over 4x10 pixels range resolution < 30 cm
320x256, 30µm pitch array under test today Objectives: TOF<2 ns and read noise < 2 e-
Vsub<0V
(1)
(2)
(3)
0
1
2
3
4
0 25 50 75 100 125 150 175 200 225 250 275
laser pulse delay (ns)
T.O
.F. N
oise
(ns
)
TOF noise measured with a flux of 560/e per pixel, at M=100 variable delay, T=80K
First 3D event driven pixel
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
14
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
Gain performance in e-APDs (xCd)
c=5.3 µm
LPE
c=4.2 µm
LPE
c=3.3 µm
MBE
c=2.9 µm
MBE
c=2.9 µm
MBE, larger depletion layer
Exponential gain exclusive electron multiplication at M>600 for c=2.9 µm (T=80K) Hole multiplication is still negliable up to high gains at high xcd c=2.9µm is compatible with high operating temperature active laser
imaging (Isat~20pA in VHg doped MCT at T=200K) Gain is dependent on junction geometry also at c=2.9µm
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
15
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
Excess noise factor in c=2.9µm e-APD (T=80 K)
M=10
M=600
M=60
qIinoise 2
FqIMinoise 2
M=1
Noise factor F~1 for c=2.9 µm MCT e-APD up to M=600 Noise is √F higher than the shot-noise
Consistent with a high stability of the exclusive electron multiplication at high xCd
Absence of 1/f noise !
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
16
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
0.01
0.1
1
10
100
1000
3.0 3.5 4.0 4.5 5.0 5.5
Cut-off wavelength (µm)
Ieq_
in -
Icc
(fA
)
e-APD sensitivity :Equivalent input dark current M=100, T=80K: FqM
iI FOV
ineq 2
20
_ 2
Icc=0, A1, ZFIcc=0, A2, ZFIcc, A1, RFIcc, A2, RF
Ieq_in =200-500 fA at M=100 for c=5.3 µm Strong reduction for shorter c Ieq_in~ fA
(10 ke/s) Needs Low noise ROIC to measure at M<100 or c<4µm
M<300
Test array diode
Measurements
without
ROIC
M=380
ROIC needed
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
17
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
M
2D identification :
Cactive=30fF (0.3Me, 90 e rms noise)
Passive thermal surveillance
Cpassive=120fF (1.2Me, 150 e rms noise)Specification Expected value Complianc
e
Max frame rate 450 Hz (10MHz, 4 outputs)
C
Linearity >99.7% from 0% to 90% of ROIC
Well-fill
C
Mini Integration time / gating
100 nsec C
Blooming No parasitic effect
C
Max diode reverse bias 7 V C
320x256 30µm pitch MCT bi-mode e-APD FPASuccess of DEFIR in 2009 (collaboration with Sofradir)
MW e-APD, c=5.3µm à 80K
TIA
3:rd demonstration of large format e-APD FPA for 2D imaging
Selex (2004) , DRS (2006), both with gain operability of 99%
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
18
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
1.0
10.0
100.0
1000.0
-9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0
Bias (V)
Gai
n
Test array gain
FPA average gain
<M>=14.1/<M>=7.7%Op50%=99.84%
320x256 30µm pitch MCT bi-mode e-APD FPA Gain measurements
f/2, 5VTest array / FPA gain
An identical gain is measured in test-arrays and FPAs Record high 99.8% operability QE>70% FPA compatible low gain dispersion (<10%) up to 7V reverse bias
Gain dispersion is dominated by the EPL ripple Reduced dispersion by using MBE or reduced ripple EPL
Excess noise factor Fmax=1.4 (consistent with similar test diodes) Excess noise factor operability <F>+/-100%=99.7% up to M=70!
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
19
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
320x256 MW HgCdTe e-APD c=5.4 µm, T=80 K(Narrow multiplication layer tunneling)
Bias M Ieq_in (A) Iobs (A) <M>dark <M>cont_gen
2.5 5 5.0E-15 4.0E-14 3.13 2.50
3.5 10 1.0E-14 7.5E-13 1.33 3.90
4.5 25 7.0E-14 7.0E-11 0.63 7.45
Flux (BB at T=290K)
FOV=0° +Photon leakage
Zero flux
Ieq_in 3.5V, M=10, C1=120fF, tint=40ms
Ieq_in=10 fA (60 ke/s)
4.5V, M=25, C1=120fF, tint=300µs
Ieq_in=70 fA (420 ke/s)
<M>dark<< <M>cont_gen. for M>10: Dark current can be suppressed using photon counting thresholding
p i n
DC generation
dark
ineqdiffdark I
IMM _
2
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
20
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
320x256 30µm pitch c=3.3µm T=80K
Flux (BB at T=290K)
Zero flux
6 V, M=6 (M/M=2.3%), C1=30fF, tint=2 s
Ieq_in=95 aA (590 e/s)
Gain ~test array gain <Mdark>=2.6 ~ <M>cont_gen=2.7
continuos GR in the junction at low gain p i n
DC generation
M=6
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
21
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
0.01
0.1
1
10
100
1000
3.0 3.5 4.0 4.5 5.0 5.5
Cut-off wavelength (µm)
Ieq_
in -
Icc
(fA
)
e-APD sensitivity :Equivalent input dark current M=100, T=80K: FqM
iI FOV
ineq 2
20
_ 2
Icc=0, A1, ZFIcc=0, A2, ZFIcc, A1, RFIcc, A2, RF
Reduction is lower than M=100 trend line Evaluation of parameter space is under way
xCd, gain, LPE, MBE hetero-structure APDs
M=380
MSW-FPA=6 (590 e-/s)
MMW-FPA=10
Late news data (14/10/2009):
M=24 (12 e-/s) at 10.5V
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
22
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
LETI/Sofradir HgCdTe e-APD Road-map
Exclusive electron multiplication HgCdTe APDs
2009 2010 2011
Q2
2D Active/passive FPA
320x256, p30µm
Q3
3D Active FPA
320x256, p30µm
Wavefront/Fringe tracking
320x256, > 1.5kFPS,
noise < 2 e-
photon counting
Single element
Photon counting array
Format to be defined
Q4
Real time BW>GHz
Single element
Q3
2D TOF imaging
320x256, p30µm
Optimizing HgCdTe e-APDs Operability >99.9%, low dark noise (10 e-/s), speed (<100ps)
Develop dedicated proximity electronics to address a maximum of applications (RON < 1 e-)
© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA
All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA
23
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
Conclusions/Perspectives MCT e-APDs
F~1 at M>600 for c=2.9 µm to 5.4 µm at T=80K Linear mode photon counting
Proportional counting (detect 1, 2.. photons) Discriminate non-amplified dark currents
Low DCR Timing precision below 100 ps No after pulsing is expected
ROIC (CMOS)-design is the key to harnest the potential of MCT e-APDs 2D active imaging array
Neq_in<12 e-/s in c=2.9 µm array at M=25 enables wave front sensing
3D AI array under testing : timing precision~1ns (15cm) 2010
Low noise-high speed wave front sensor Neq_in < 1 e-/s at M>10 Single element photon counting