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HgCdTe avalanche photodiodes development at CEA/Leti-Minatec

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

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HgCdTe avalanche photodiodes development at CEA/Leti-Minatec

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  1. 2009 HgCdTe avalanche photodiodes development at CEA/Leti-Minatec Johan Rothman CEA: L. Mollard, S. Bisotto Sofradir: X. Lefoule, F. Pistone Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  2. 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 LETI-Minatec and Sofradir • Conclusion/perspectives Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  3. 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 Detector lab and fab Sofradir • ROIC design • EO FPA test • E-APD FPA industrialisation • Fab etc.. System labs e-APDs Astro-physics labs • LAOG ( Grenoble) and LAM (Marseille) • Adaptiv optics, fringe tracking • Photon-counting imaging ONERA • E-APD physics • Multiplication process (gain, noise) • EO FPA test Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  4. The photodiode: an ideal light detector? High timing resolution QE100% 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! M x Photo-current M PE noise Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  5. 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) Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  6. Exclusive electron multiplication in HgCdTe APDs HgCdTe e-APD lc=5µm, T=80K • 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 Gain M=I/ICC Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  7. A new horizon of applications from visible to IR wavelengths with MCT e-APDs :(M>1000, F~1, Neq_in<10 000 e/s) This talk (1) • 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 This talk (2) Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  8. Performance optimization of HgCdTe e-APDs? • MW (lc=4.2-5µm) e-APD performances: • M>100, F=1.2, Ieq_in~10000 e/s, tresp~2 ns, Top<100K Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  9. 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 Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  10. 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) Output count probability distribution for <M>=300 and F=1.04 1 photon 2 photons Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  11. 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 Output count probability distribution for <M>=300 and F=1.04 DC generation Distributed dark-current generation p i n 1 photon 2 photons <M>dark Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  12. Response time optimization in APDs 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! Response time jitter  limits the timing precision Collection of minority electrons p Transit time of eand h n- Depletion layer = mutliplication region E RC charge evacuation n+ • G. Perrais et al. JEM, 37, 2008 • G. Perrais et al. JEM, 38, 2009 • J. Rothman et al. to be published, JEM, 40 (2010) Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  13. 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 move towards photon counting (2008): Active 3D Imaging 4x10 test FPA, 40µm pitch First 3D event driven pixel (2) TOF noise measured with a flux of 560/e per pixel, at M=100 variable delay, T=80K (1) (3) Vsub<0V "Advanced pixel design for infrared 3D LADAR imaging" F. Guellec, SPIE DSS, 6940-84 • 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- Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  14. Gain performance in e-APDs (xCd) lc=3.3 µm MBE lc=4.2 µm LPE • 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 lc=5.3 µm LPE lc=2.9 µm MBE lc=2.9 µm MBE, larger depletion layer Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  15. Excess noise factor in lc=2.9µm e-APD (T=80 K) 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 ! M=600 M=60 M=10 M=1 Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  16. e-APD sensitivity :Equivalent input dark current M=100, T=80K: 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 Icc=0, A1, ZF Icc=0, A2, ZF Icc, A1, RF Icc, A2, RF Test array diode Measurements without ROIC M=380 ROIC needed Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  17. 320x256 30µm pitch MCT bi-mode e-APD FPASuccess of DEFIR in 2009 (collaboration with Sofradir) MW e-APD, lc=5.3µm à 80K TIA 2D identification : Cactive=30fF (0.3Me, 90 e rms noise) M Passive thermal surveillance Cpassive=120fF (1.2Me, 150 e rms noise) 3:rd demonstration of large format e-APD FPA for 2D imaging Selex (2004) , DRS (2006), both with gain operability of 99% Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  18. 320x256 30µm pitch MCT bi-mode e-APD FPA Gain measurements Test array / FPA gain f/2, 5V <M>=14.1 s/<M>=7.7% Op50%=99.84% • 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! Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  19. 320x256 MW HgCdTe e-APD lc=5.4 µm, T=80 K(Narrow multiplication layer  tunneling) <M>dark<< <M>cont_gen. for M>10: Dark current can be suppressed using photon counting thresholding 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) Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  20. 320x256 30µm pitch lc=3.3µm T=80K Gain ~test array gain <Mdark>=2.6 ~ <M>cont_gen=2.7 continuos GR in the junction at low gain 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 M=6 Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  21. e-APD sensitivity :Equivalent input dark current M=100, T=80K: Reduction is lower than M=100 trend line Evaluation of parameter space is under way xCd, gain, LPE, MBE hetero-structure APDs Icc=0, A1, ZF Icc=0, A2, ZF Icc, A1, RF Icc, A2, RF MMW-FPA=10 M=380 MSW-FPA=6 (590 e-/s) Late news data (14/10/2009): M=24 (12 e-/s) at 10.5V Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  22. LETI/Sofradir HgCdTe e-APD Road-map photon counting Single element Q4 Real time BW>GHz Single element Wavefront/Fringe tracking 320x256, > 1.5kFPS, noise < 2 e- 2010 2009 2011 Exclusive electron multiplication HgCdTe APDs • 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-) Q2 2D Active/passive FPA 320x256, p30µm Q3 3D Active FPA 320x256, p30µm Photon counting array Format to be defined Q3 2D DTOF imaging 320x256, p30µm Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

  23. 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 • 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 Detectors for Astronomy Workshop 2009 - HgCdTe e-APDs at CEA/LETI - Johan Rothman

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