HgCdTe avalanche photodiodes development at CEA/Leti-Minatec Johan Rothman CEA: L. Mollard, S. Bisotto Sofradir: X.
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Transcript HgCdTe avalanche photodiodes development at CEA/Leti-Minatec Johan Rothman CEA: L. Mollard, S. Bisotto Sofradir: X.
2009
2007
HgCdTe avalanche
photodiodes development
at CEA/Leti-Minatec
Johan Rothman
CEA: L. Mollard, S. Bisotto
Sofradir: X. Lefoule, F. Pistone
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Detectors for Astronomy Workshop 2009 - 1
HgCdTe e-APDs at CEA/LETI - Johan Rothman
Outline
HgCdTe e-APD development in France
Why HgCdTe e-APDs?
Performance
Applications
HgCdTe e-APDs for photon-counting
Focal plane array results
HgCdTe e-APD road map at LETIMinatec and Sofradir
Conclusion/perspectives
2007
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Detectors for Astronomy Workshop 2009 - 2
HgCdTe e-APDs at CEA/LETI - Johan Rothman
HgCdTe e-APD development in France
CEA/LETI
E-APD technology
and design
Detector lab and fab
Sofradir
ROIC design
EO FPA test
E-APD FPA
industrialisation
Epitaxy, µ-tech.
E-APD physics and
test
Response time
Multiplication process
(gain, noise)
Sensitivity limits
2007
ROIC design
EO FPA test
System labs
e-APDs
ONERA
E-APD physics
Multiplication process
(gain, noise)
EO FPA test
Fab etc..
Astro-physics labs
LAOG ( Grenoble) and
LAM (Marseille)
Adaptiv optics, fringe
tracking
Photon-counting imaging
© CEA 2008. Tous droits réservés.
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Detectors for Astronomy Workshop 2009 - 3
HgCdTe e-APDs at CEA/LETI - Johan Rothman
The photodiode: an ideal light detector?
High timing resolution
QE100% i.e. no loss of information
High Sensitivity
Dark currents can be lower than 1 electron/s
Limited by proximity-electronics (PE) noise
Can be reduced by amplified photo detection!
2007
M x Photo-current
M
PE noise
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Detectors for Astronomy Workshop 2009 - 4
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
t
t dt
t int
Compatible with imaging and telecom applications
…but furious (other than HgCdTe-APDs…)
2007
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 gainBand-Width product < 340GHz (Intel record, Nature
Photonics, 3, 2008)
After pulsing probability >0 (photon counting)
Dead time (photon counting)
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Detectors for Astronomy Workshop 2009 - 5
HgCdTe e-APDs at CEA/LETI - Johan Rothman
Exclusive electron multiplication in HgCdTe
APDs
10000.0
HgCdTe e-APD
lc=5µm, T=80K
Gain M=I/I
CC
Gain
1000.0
100.0
10.0
1.0
-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)
Exponential gain without avalanche break down (Beck,DRS, 2001)
2007
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
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Detectors for Astronomy Workshop 2009 - 6
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
This talk (1)
Quantum optics
Physics, astronomy, quantum cryptography
Imaging in Astronomy, biomedical applications, high-energy physics
Astronomy : higher order correlation functions!
t
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
t int
Long range identification, safe planetary landing (NASA), bio-medical
(fluorescence imaging), observation through semi transparent
surfaces
Passive amplified imaging
This talk (2)
Low flux applications ; hyper spectral imaging, wave front detection
for astronomy, high dynamic range
2007
t dt
The geiger modes is not (yet) possible due to the absence of
avalanche break-down threshold
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Detectors for Astronomy Workshop 2009 - 7
HgCdTe e-APDs at CEA/LETI - Johan Rothman
Performance optimization of HgCdTe eAPDs?
MW (lc=4.2-5µm) e-APD performances:
M>100,
F=1.2, Ieq_in~10000 e/s, tresp~2 ns, Top<100K
Application
Photon counting
M, F ok
Passive amplified
imaging
M, F, tresp ok
Critical
parameter
1. Reduce tresp :
<100 ps
Reduce Ieq_in :
<1000 e/s
(Operability)
1. Reduce Ieq_in :
< 1000 e/s
2. Increase Top
(Operability)
This talk
E-APD gain (F~1)
for photon
counting
Response time
limits (jitter)
Impact of xCd:
Gain, F, dark
current
(Diodes and FPAs)
2007
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Detectors for Astronomy Workshop 2009 - 8
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
2007
Timer :Estimation of the time of
arrival of the photons
3D imaging
Quantum optics and imaging
higher order photon correlation
functions
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Detectors for Astronomy Workshop 2009 - 9
HgCdTe e-APDs at CEA/LETI - Johan Rothman
Exclusive electron multiplication for
Linear mode proportional photon counting
Output count probability distribution for <M>=300 and F=1.04
0.014
probability density
0.012
0.01
1 photon
0.008
2 photons
0.006
0.004
0.002
0
0
2007
100
200
300
400
500
600
700
800
900
Output counts
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 (GMAPDs ~ 10MHz)
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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
Detectors for Astronomy Workshop 2009 - 10
HgCdTe e-APDs at CEA/LETI - Johan Rothman
Exclusive electron multiplication for
Linear mode proportional photon counting
Output count probability distribution for <M>=300 and F=1.04
DC generation
0.014
Distributed dark-current
generation
probability density
0.012
p
i
n
0.01
1 photon
0.008
2 photons
0.006
0.004
M
0.002
1 1
ln M diff M diff
M diff
dark _ cont _ gen
0
0
100
<M>dark
2007
200
300
400
500
600
700
800
900
Output counts
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
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Detectors for Astronomy Workshop 2009 - 11
HgCdTe e-APDs at CEA/LETI - Johan Rothman
Response time optimization in APDs
p
n-
Response time
jitter limits
the timing
precision
E
Depletion layer =
mutliplication region
n+
Collection of minority electrons
Collection of
minority electrons
Transit time of e
and h
RC charge
evacuation
2007
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!
1.
2.
3.
© CEA 2008. Tous droits réservés.
G. Perrais et al. JEM, 37, 2008
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G. Perrais et al. JEM, 38, 2009
Detectors for Astronomy Workshop 2009 - 12
J. Rothman et al. to be published, JEM, 40 (2010)
HgCdTe e-APDs at CEA/LETI - Johan Rothman
First move towards photon counting (2008):
Active 3D Imaging 4x10 test FPA, 40µm pitch
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)
First 3D event driven
(2)pixel
4
Pixel outputs :
TOF noise measured with
a flux of 560/e per pixel, at
M=100 variable delay,
T=80K
Return intensity
Track & Hold
(analog voltage ramp)
Vref
+
N1
OTA
-
Iin
(1)
+
Vth
N2
Lock
T.O.F.
T.O.F. Noise (ns)
Time base
N3
-
C3D
C2D
Vsub<0V
2007
(3)
Precharge
3
2
1
RESET
"Advanced pixel design for infrared 3D LADAR imaging
"
F. Guellec, SPIE DSS, 6940-84
0
0
25 50 75 100 125 150 175 200 225 250 275
laser pulse delay (ns)
Sequential and spatial DTOF<2ns over 4x10 pixels range
resolution < 30 cm
320x256, 30µm pitch array under test today
Objectives: DTOF<2 ns and read noise < 2 e-
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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
Detectors for Astronomy Workshop 2009 - 13
HgCdTe e-APDs at CEA/LETI - Johan Rothman
Gain performance in e-APDs (xCd)
lc=3.3 µm lc=4.2 µm
MBE
LPE
lc=5.3 µm
LPE
lc=2.9 µm
MBE
lc=2.9 µm
MBE, larger depletion layer
2007
Exponential gain exclusive electron multiplication at M>600
for lc=2.9 µm (T=80K)
Hole multiplication is still negliable up to high gains at high xcd
lc=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 lc=2.9µm
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Detectors for Astronomy Workshop 2009 - 14
HgCdTe e-APDs at CEA/LETI - Johan Rothman
Excess noise factor in lc=2.9µm e-APD (T=80 K)
M=600
M=60
inoise M 2qI F
M=10
M=1
inoise 2qI
2007
Noise factor F~1 for lc=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 !
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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
Detectors for Astronomy Workshop 2009 - 15
HgCdTe e-APDs at CEA/LETI - Johan Rothman
e-APD sensitivity :
Equivalent input dark current M=100, T=80K:
I eq _ in
1000
Ieq_in - Icc (fA)
Test array diode
Measurements
without
ROIC
Icc=0, A1, ZF
Icc=0, A2, ZF
Icc, A1, RF
Icc, A2, RF
100
2
iFOV
0
2qM 2 F
10
M=380
1
ROIC needed
0.1
0.01
2007
3.0
3.5
4.0
4.5
5.0
5.5
Cut-off wavelength (µm)
Ieq_in =200-500 fA at M=100 for lc=5.3 µm
Strong reduction for shorter lc Ieq_in~ fA
(10 ke/s)
Needs Low noise ROIC to measure at M<100 or lc<4µm
M<300
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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
Detectors for Astronomy Workshop 2009 - 16
HgCdTe e-APDs at CEA/LETI - Johan Rothman
320x256 30µm pitch MCT bi-mode e-APD FPA
Success of DEFIR in 2009 (collaboration with Sofradir)
MW e-APD,
lc=5.3µm à 80K
TIA
M
2007
2D identification :
Cactive=30fF (0.3Me, 90 e rms noise)
Passive thermal surveillance
Cpassive=120fF (1.2Me, 150 e rms noise)
Specification
Expected value
Compliance
Max frame rate
450 Hz
(10MHz, 4 outputs)
C
>99.7% from 0% to
90% of ROIC Well-fill
C
100 nsec
C
No parasitic effect
C
7V
C
Linearity
Mini Integration time / gating
Blooming
Max diode reverse bias
3:rd demonstration of large format e-APD FPA for 2D imaging
Selex (2004) , DRS (2006), both with gain operability
99% Workshop 2009 - 17
Detectors of
for Astronomy
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HgCdTe e-APDs at CEA/LETI - Johan Rothman
320x256 30µm pitch MCT bi-mode e-APD FPA
Gain measurements
Test array / FPA gain
f/2, 5V
1000.0
<M>=14.1
s/<M>=7.7%
Op50%=99.84%
Test array gain
FPA average gain
Gain
100.0
10.0
1.0
-9.0
-7.0
-6.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
Bias (V)
2007
-8.0
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!
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Detectors for Astronomy Workshop 2009 - 18
HgCdTe e-APDs at CEA/LETI - Johan Rothman
320x256 MW HgCdTe e-APD lc=5.4 µm, T=80 K
(Narrow multiplication layer tunneling)
4.5V, M=25, C1=120fF, tint=300µs
Ieq_in=70 fA (420 ke/s)
Flux (BB at T=290K)
Zero flux
FOV=0° +
Photon leakage
Ieq_in
3.5V, M=10, C1=120fF, tint=40ms
Ieq_in=10 fA (60 ke/s)
DC generation
2007
M dark
M
2
diff eq _ in
I
I dark
p
i
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
n
<M>dark<< <M>cont_gen. for M>10:
Dark current can be suppressed using photon counting thresholding
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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
Detectors for Astronomy Workshop 2009 - 19
HgCdTe e-APDs at CEA/LETI - Johan Rothman
320x256 30µm pitch lc=3.3µm T=80K
Flux (BB at T=290K)
6 V, M=6 (sM/M=2.3%), C1=30fF, tint=2 s
Ieq_in=95 aA (590 e/s)
Zero flux
2007
Gain ~test array gain
<Mdark>=2.6 ~ <M>cont_gen=2.7
continuos GR in the junction at low gain
DC generation
p
i
n
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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
Detectors for Astronomy Workshop 2009 - 20
HgCdTe e-APDs at CEA/LETI - Johan Rothman
e-APD sensitivity :
Equivalent input dark current M=100, T=80K:
I eq _ in
2
iFOV
0
2qM 2 F
1000
Icc=0, A1, ZF
Icc=0, A2, ZF
Icc, A1, RF
Icc, A2, RF
Ieq_in - Icc (fA)
100
MMW-FPA=10
10
M=380
1
0.1
MSW-FPA=6 (590 e-/s)
0.01
2007
3.0
3.5
4.0
4.5
5.0
5.5
Cut-off wavelength (µm)
Late news data (14/10/2009):
M=24 (12 e-/s) at 10.5V
Reduction is lower than M=100 trend line
Evaluation of parameter space is under way
xCd, gain, LPE, MBE hetero-structure APDs
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Detectors for Astronomy Workshop 2009 - 21
HgCdTe e-APDs at CEA/LETI - Johan Rothman
LETI/Sofradir HgCdTe e-APD Road-map
2010
2009
2011
Exclusive electron multiplication HgCdTe APDs
Q2
2D Active/passive FPA
320x256, p30µm
Q3
3D Active FPA
320x256, p30µm
Q4
Real time BW>GHz
Single element
Wavefront/Fringe tracking
320x256, > 1.5kFPS,
noise < 2 e-
Photon counting array
Format to be defined
2007
Q3
2D DTOF imaging
320x256, p30µm
photon counting
Single element
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-)
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Detectors for Astronomy Workshop 2009 - 22
HgCdTe e-APDs at CEA/LETI - Johan Rothman
Conclusions/Perspectives
MCT e-APDs
F~1 at M>600 for lc=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
2007
2D active imaging array
Neq_in<12 e-/s in lc=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
© CEA 2008. Tous droits réservés.
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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
Detectors for Astronomy Workshop 2009 - 23
HgCdTe e-APDs at CEA/LETI - Johan Rothman