IR Detectors Developments for Space Applications

Transcription

1 CMOS Image Sensors for High Performance Applications Toulouse, France, 6 th & 7 th December 2011 IR Detectors Developments for Space Applications Harald Weller SELEX GALILEO Infrared Ltd, Southampton, UK

2 SELEX GALILEO Southampton Nearly 50 years experience in research and development Vertically integrated, Southampton s manufacturing starts from basic elements Hg, Cd and Te Experienced in growing and processing a range of semiconductor materials (PC and PV technologies) Clean room capacity and infrastructure to run higher volumes (11,200 m² facility of which 3,200 m² are clean rooms) Design of custom integrated read out circuits Site highly specialised in packaging and testing of sensors (including cryogenics) with capability of moving into adjacent sensor markets Developing electronics design capability

3 RECENT PROJECTS SPACE APPLICATIONS MTG pre-development ( , concluded) ESA-APD ( , concluded) Sentinel 3 pre-development ( , concluded) METimage pre-development (on-going) ESO Gravity (on-going) ESA Large Format Near InfraRed (LFNIR)

4 Evolution of APDs at SELEX-GALILEO x256, 2D, (SWIFT) x256, 2D and 3D, (SWALLOW) x256, 2D and Thermal Mode, (SWAN) x256, SW, High Speed, (SAPHIRA) MAJOR TRIALS International Airborne 320x256, Multifunctional, Thermal, 2D, 3D and Range Finder 2011

5 SW APD - Application areas 1000 Photon counting or linear mode detectors Cut-off wavelength Avalanche gain Burst Illumination LIDAR (BIL) imaging 2.5 µm 3 µm 3.5 µm 4 µm 4.5 µm Bias volts Low background flux applications

6 HgCdTe Avalanche Photodiode Detector with >2 um Cut-off Wavelength ESA/ESTEC Contract 21751/08/N/EM

7 ESA APD Objectives Objectives of Contract Design and manufacture a mercury cadmium telluride (MCT) avalanche photodiode (APD) detector and Transimpedance (TIA) pre-amplifier circuit such that the MCT APD/TIA combination meets a set of performance criteria suitable for a LIDAR receiver Test and characterise the MCT-APD/TIA Why use MCT for Avalanche Photodiodes? Near-ideal single-carrier cascade avalanche almost noiseless gain in the pixel Composition-tuneable bandgap suitable for many IR wavelengths

8 ESA APD - Construction: Encapsulated Detector Hybrid Preamp Die Final Device Metallised Leadout Encapsulation

9 ESA APD - Performance Criteria Summary of Performance Demands Parameter Operating wavelength Value 2051 nm Detector quantum efficiency > 70% Active area diameter > 150µm Excess noise factor (F) <1.5 Operating temperature > 200 K Input signal/dynamic range. minimum: 8000 maximum: 2E6 Bandwidth NEP Gain stability Linearity Total ionizing dose Proton irradiation >20 MHz < 100 fw/ Hz 0.1% rms. 5% rms 5 krad (Si) minimum 1E10 p/cm2

10 ESA APD - Performance Summary Summary Conditions: Low flux: Avalanche Bias: Signal Frequency: Noise frequency: 7.9kphotons/50ns/pixel from 1000K Blackbody Source 9.25 ± 0.05 Volts reverse bias 500Hz (mechanical chopper) 500kHz (10kHz measurement bandwidth) Device Identity Low Flux Signal Low Flux Noise White Noise (No flux) Low Flux QE* NEP mv nv/ Hz nv/ Hz - fw/ Hz 4720-E G L M I J K K

11 HgCdTe Avalanche Photodiode Detector with >2 um Cut-off Wavelength Radiation Testing

12 ESA APD - Dark Current: Whole Pixel 100 Dark Current Detector 10G44092-K03 Element Dark Current at 9.3V bias (na) Before Radiation After Radiation Element Dark Current (na) 10 Detector* 4720-E G L I J Diode Bias (V)

13 ESA APD - Total Ionising Dose Facility: Dose rate: Condition: Time between irradiation and test: ESTEC Co-60, Noordwijk, Netherlands 2.5 krads/hr (approx) Powered, biased, room temperature 15 days L01 5kRad (Si) 4720-E05 10kRad (Si) Before After Change Units Signal % mv Noise (Low Flux) % nv/ Hz Noise (Blind) % nv/ Hz Gain % - Cut-off % µm NEP fw/ Hz Before After Change Units Signal % mv Noise (Low Flux) % nv/ Hz Noise (Blind) % nv/ Hz Gain % - Cut-off % µm NEP fw/ Hz

14 ESA APD - Proton Facility: Dose rate: Condition: Time between irradiation and test: PSI, Villigen, Switzerland 1 10¹º protons/cm², 3 10¹º protons/cm² (10MeV eq.). Unpowered, room temperature 57 days Device ID: I02 Device ID: J02 Dose: p+/cm², 10MeV eq. Dose: p+/cm², 10MeV eq. Before After Change Units Before After Change Units Signal % mv Noise (Low Flux) % nv/ Hz Noise (Blind) % nv/ Hz Gain % - Cut-off % µm NEP fw/ Hz Signal % mv Noise (Low Flux) % nv/ Hz Noise (Blind) % nv/ Hz Gain % - Cut-off % µm NEP fw/ Hz

15 ESA APD - Summary Novel approach of hybridising diode directly to TIA preamplifier has been successful Device is sensitive to primary wavelength (2.051µm) but also suited to other wavelengths (1.3µm to 2.2µm) The device exceeds the key performance criterion (NEP<100fW Hz) Most other performance criteria achieved (though some not fully demonstrated) Manufacturing method for diode established. Viability of manufacturing demonstrated yields sustainable Encapsulated detector designed (and available for breadboard activities) Exploitation of device in LIDAR system yet to be demonstrated

16 SW APD MCT APD for Wavefront Sensors and Interferometry

17 Uniformity of avalanche gain Normalised laser signal as function of avalanche gain Output signal (mv) Pixel number Gain - x14 Gain - x28 Gain - x38 Avalanche gain adds virtually nothing to non-uniformity Depends only on voltage and alloy composition

18 Wavefront sensors and interferometry Typical requirements: Avalanche gains x10 to x30 Waveband in region of 1.0 to 2.5µm - mainly J,H and K band 256x256 array Frame rate >1KHz Sensitivity <3e rms at pixel rate of 5MHz/channel 24µm pixel size Multiple readout windows with independent reset Low noise floor Non-destructive readout 32 parallel outputs Temperature range 30K to 80K Acknowledgements: All the data presented here is courtesy of European Southern Observatories, ESO With special thanks to Dr Gert Finger

19 SW APD evaluation at ESO APD sensor SELEX-Galileo Swallow 3D detector Operated in simple non-destructive read mode Voltage controlled avalanche gain 2.5µm cutoff arrays ESO APD test kit Cooled optics for few photons imaging Cryogenic symmetric pre-amplifier Two stage engine to 30K Typical exposure

20 Avalanche gain versus bias voltage black diamonds: measured exponential dependence on bias voltage ROIC ME788 Cutoff wavelength µm Temperature - 40K model Data courtesy of ESO

21 Noise histogram with eapd APD sensor ROIC ME788 Cutoff µm Temperature - 40K Int. time 5.06ms Bandwidth 5MHz APD gain 33x Data courtesy of ESO

22 9.3 e/pixel test pattern versus APD gain APD sensor Optics ROIC ME788 Cutoff wavelength µm Temperature - 40K Integration time 5.06ms Bandwidth 5MHz Filter K short Pattern contrast 9.3 e/pixel Data courtesy of ESO

23 1.75 e/pixel sensitivity with APD gain of 33 APD sensor Optics ROIC ME788 Cutoff wavelength µm Temperature - 40K Integration time 5.06ms Bandwidth 5MHz APD gain 33x Filter K short Pattern contrast 1.75 e/pixel Signal processing Double correlated clamp 16 frames averaged Data courtesy of ESO

24 SW APD Fowler sampling number of nondestructive readouts increasing with integration time 5.06 ms /frame 2.7 erms 1 Fowler pair (DCS) noise integration time 42 ms 1.2 erms 8 Fowler pairs for integration time 50ms shotnoise = with I dark =84 e/s for λ c =2.65 µm HgCdTe 50 ms integration time possible without limiting sensitivity by shot noise Data courtesy of ESO

25 SW APD Excess Noise Factor excess noise close to unity for APD gain up to 33 excess noise determined form ratio of photometric gain and gain obtained from photon transfer curve Data courtesy of ESO

26 Noise Histogram of SW APD ADP gain 33 5 MHz/channel Data courtesy of ESO

27 Conclusions from pre-development study Sensitivity <3e rms is achievable using HgCdTe eapds for imaging in J H and K band with 5MHz clock and >1KHz frame rate SELEX-Galileo were down-selected to supply sensors for the GRAVITY Program and contracted to design a custom ROIC

28 APD sensors in the VLT Interferometer European Southern Observatories, ESO Very Large Telescope, VLT cluster of four 8.2m unit telescopes The SW infrared APD detectors Critical to the GRAVITY system are the four infrared wavefront sensors and one fringe tracker to correct the atmospheric turbulence at each telescope, and stabilise the fringe phase in the VLTI beam relays. VLTI requirements Adaptive optics needed to correct for atmospheric distortion using embedded sources (galactic center). The IRIS instrument is used for simultaneous first order wavefront corrections (tip-tilt) of all 4 telescopes on a single detector APD wavefront sensor: 96x96 256x256 array at K band Frame rate >1KHz Sensitivity <3e rms at 5MHz 32 parallel outputs 24µm pixel size Non-destructive readout

29 SAPHIRA - full custom ROIC for GRAVITY GRAVITY Full Custom ROIC - SAPHIRA General architecture 320x256 on 24µm pitch with either 32, 16, 8 or 4 outputs Pixel mapping 32 outputs organised as 32 sequential pixels in row (ie row scan requires 10 clocks). Windowing Multiple windows each independently resettable Readout Non-destructive readout with internal glow protection permitting Fowler sampling with a large number of readouts to reduce readout noise to <1 e rms Full custom pixel Designed for low intrinsic noise Variable integration capacitor Voltage clamp to minimise persistence Glow protection APD protection circuit 15fF integration node capacitance SAPHIRA

30 Summary of eapd arrays SWIFT - Multifunctional Array 2D and 3D Burst Illumination LIDAR Thermal and low light level imaging Scene-based laser range finding SAPHIRA Low Photon Flux Imaging Spectroscopy Ultra fast framing

31 Conclusions Benefits of SW APD for LIDAR receiver applications were demonstrated APD radiation results obtained Existing SW APD technology independently characterised, demonstrating sensitivity of <3e rms Gravity custom ROIC for SW APD in development