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 Presentation
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1
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
HgCdTe avalanche photodiodes development at CEA/Leti-MinatecJohan Rothman
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2
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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-
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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
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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
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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
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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
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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)
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8
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
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
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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
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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
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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
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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
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13
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
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
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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
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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
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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%
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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!
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19
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
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
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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
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22
2007
Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman
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