James Beletic's presentation

High Performance Imaging Sensors 

for Astronomy & Civil Space 

18 March 2010 

James W. Beletic

Teledyne – NASA’s s and ESA’s s Partner in Astronomy 

HST WISE JWST 

J-MAPS 

NICMOS, WFC3, ACS Repair 

Bands 1 & 2 

NIRCam, NIRSpec, FGS 

1 st CMOS for astronomy 

Rosetta 

Mars 

Reconnaissance 

Orbiter 

Deep Impact 

& EPOXI 

New Horizons 

Lander (çiva) CRISM (Vis & IR) IR spectrograph IR spectrograph 

JDEM 

Joint Dark Energy Mission 

NASA and U.S. DOE 

(Department of Energy)

Hubble Space Telescope

Hubble Space Telescope 

Wide Field Camera 3 

H1-R 

Quantum Efficiency = 85-90% 

Dark current (145K) = 0.02 e-/pix/sec 

Readout noise = 25 e- (single CDS) 

GSFC DCL Measurement 

• 1024×1024 pixels, 18.5 micron pitch 

• Substrate-removed 1.7 μm HgCdTe arrays 

• Nearly 30x increase in HST discovery efficiency

James Webb Space Telescope (JWST)

JWST - James Webb Space Telescope 

15 Teledyne 2K×2K infrared arrays on board (~63 million pixels) 

6.5m mirror 

Earth 

sunshield 

FGS 

(Fine Guidance Sensors) 

• International collaboration 

• 6.5 meter primary mirror and 

tennis court size sunshield 

• 2015 launch on Ariane 5 rocket 

• L2 orbit (1 million miles from Earth) 

JWST will find the “first light” 

objects after the Big Bang, and 

will study how galaxies, stars 

and planetary systems form 

NIRSpec 

(Near Infrared Spectrograph) 

SIDECAR ASIC 

Focal Plane Electronics 

15 ASICs will operate in JWST 

One ASIC per H2RG array 

NIRCam 

(Near Infrared Camera) 

3 individual MWIR 2Kx2K 

• Acquisition and guiding 

• Images guide stars for telescope 

stabilization 

• Canadian Space Agency 

1x2 mosaic of MWIR 2Kx2K 

• Spectrograph 

• Measures chemical composition, 

temperature and velocity 

• European Space Agency / NASA 

All Sensors Delivered 

ASIC deliveries to be completed in June 2010 

Two 2x2 mosaics 

of SWIR 2Kx2K 

Two individual 

MWIR 2Kx2K 

• Wide field imager 

• Studies morphology of objects 

and structure of the universe 

• U. Arizona / Lockheed Martin 

6

NASA’s s Partner for Earth Science 

LDCM 

TIRS 

NPOESS 

CrIS 

CHANDRAYAAN-1 

GOES-R 

ABI 

(LWIR) 

(SWIR) 

GLORY 

Moon Mineralogy Mapper 

(Vis-IR) 

EO-1 

AURA 

Tropospheric Emission Spectrometer 

IR FT Spectrometer 

OCO-R 

Orbiting Carbon 

Observatory 

(Vis & IR) 

Visible to 16.5 microns 

LEISA 

Atmospheric 

Corrector 

(IR arrays) 

Working on development for several future missions 

HyspIRI (Vis-SWIR and Thermal IR), ACE, OCO Re-flight, AVIRISng, PRISM, Himawari

Moon Mineralogy Mapper 

Discovers Water on the Moon 

Focal Plane Assembly 

Sensor Chip Assembly 

Instrument at JPL before 

shipment to India 

Completion of Chandrayaan-1 spacecraft integration 

Moon Mineralogy Mapper is white square at end of arrow 

Chandrayaan-1 in the 

Polar Satellite Launch Vehicle 

Launch from Satish 

Dhawan Space Centre 

Moon Mineralogy Mapper resolves visible and infrared 

to 10 nm spectral resolution, 70 m spatial resolution 

100 km altitude lunar orbit

Orbiting Carbon Observatory (OCO) 

Teledyne Focal Plane Arrays 

• Three flight FPAs: 

• O 2 A band at 0.758-0.772 µm 

• weak CO 2 band at 1.594 -1.619 µm 

• strong CO 2 band at 2.042-2.082 µm 

• Hawaii-1RG readout is used for both HyViSI and SWIR 

FPAs with same mechanical and nearly same electrical 

interface for all three OCO spectrometers. 

• Re-Flight may use substrate-removed HgCdTe for all 

three bands 

9

Leading Supplier of Infrared Arrays To Ground-based Astronomy 

• Shipped over 45 science grade 2048×2048 pixel infrared arrays for 

facility class instruments to the major ground based observatories 

• Eight 2 x2 mosaics of H2 / H2RGs at ground based telescopes 

Magellan Telescopes, OCIW - Chile 

Calar Alto Observatory – Spain 

ESO VLT 8.2-m telescope 

ESO Very Large Telescope (VLT) Facility - Chile 

10

The Technologies of High Performance Imagers 

11

An electron-volt 

(eV) 

is extremely small 

15 H2RG 

2K×2K arrays 

63 million pixels 

1 eV = 1.6 • 10 -19 J (J = joule) 

1 J = N • m = kg • m • sec -2 •m 

1 kg raised 1 meter = 9.8 J = 6.1 • 10 19 eV 

• The energy of a photon is VERY small 

– Energy of SWIR (2.5 μm) photon is 0.5 eV 

• In 5 years, JWST will take ~1 million images 

– 1000 sec exp., 15 H2RGs, 90% duty cycle 

– Photons / H2RG image ≈ 3.6 × 10 10 photons 

• 5% pixels at at 85% full well 

• 10% " at at 40% full well 



Full well 

85,000 e- 

– Total # SWIR photons detected ≈ 3.6 × 10 16 

– Total energy detected ≈ 1.8 × 10 16 eV 

• Drop peanut M&M ® candy (~2g) from 

height of 15 cm (~6 inches) 

– Potential energy ≈ 1.8 x 10 16 eV 

15 cm peanut M&M ® drop is 

equal to the energy detected 

during 5 year operation of the 

James Webb Space Telescope!

Hybrid CMOS Infrared Imaging Sensors 

Three Key Technologies 

1. Growth and processing of the 

HgCdTe detector layer 

2. Design and fabrication of the 

CMOS readout integrated circuit 

(ROIC) 

3. Hybridization of the detector layer 

to the CMOS ROIC 

15

6 Steps of CMOS-based Optical / IR Photon Detection 

Anti-reflection coating 

Substrate removal 

Detector Materials 

HgCdTe, Si 

1. Light into detector 

2. Charge Generation 

Quantum 

Efficiency 

Electric Fields in detector 

collect electrical charge 

p-n junction 

Source follower 

3. Charge Collection 

4. Charge-to-Voltage 

Conversion 

Point 

Spread 

Function 

Sensitvity 

HYBRID SENSOR 

CHIP ASSEMBLY (SCA) 

Random access 

or full frame read 

5. Signal Transfer 

SIDECAR 

ASIC 

6. Digitization 

16

Crystals are excellent detectors of light 

• Simple model of atom 

– Protons (+) and neutrons in the nucleus 

with electrons orbiting 

Silicon crystal lattice 

• Electrons are trapped in the crystal lattice 

– by electric field of protons 

• Light energy can free an electron from the 

grip of the protons, allowing the electron to 

roam about the crystal 

– creates an “electron-hole” pair. 

• The photocharge can be collected and 

amplified, so that light is detected 

• The light energy required to free an electron 

depends on the material.

II III IV V VI 

Detector Families 

Si - IV semiconductor 

HgCdTe - II-VI semiconductor 

InGaAs & InSb - III-V semiconductors

Tunable Wavelength: Unique property of HgCdTe 

Hg 1-x Cd x Te Modify ratio of Mercury and Cadmium to “tune” the bandgap energy 

2 

( 1− 

x) 

E g = −0.302 

+ 1.93x 

− 0.81x 

+ 0.832 x + 5.35 × 10 T 2 

G. L. Hansen, J. L. Schmidt, T. N. Casselman, J. Appl. Phys. 53(10), 1982, p. 7099 

3 

−4 

20

Absorption Depth of Photons in HgCdTe 

Rule of Thumb 

Thickness of HgCdTe layer 

needs to be about equal 

to the cutoff wavelength 

Absorption Depth 

Thickness of detector material that absorbs 63.2% of the radiation 

1/e of the energy is absorbed 

1 absorption depth(s) 63.2% of light absorbed 

2 86.5% 

3 95.0% 

4 98.2% 

For high QE, thickness of detector material should be ≥ 3 absorption depths 

21

Molecular Beam Epitaxy (MBE) Growth of HgCdTe 

RIBER 3-in MBE Systems 

3 inch diameter platen 

allows growth on one 

6x6 cm substrate 

RIBER 10-in MBE 49 System 

10 inch diameter 

platen allows 

simultaneous growth 

on four 6x6 cm 

substrates 

More than 7500 HgCdTe 

wafers grown to date 

22

HgCdTe Cutoff Wavelength 

Atmospheric Transmission 

Wavelength (microns) 

“Standard” Ground-based astronomy 

cutoff wavelengths 

Near infrared (NIR) 

1.75 µm J,H 

Short-wave infrared (SWIR) 2.5 µm J,H,K 

Mid-wave infrared (MWIR) 5.3 µm J,H,K,L,M 

23





HgCdTe, Si 



Quantum 

Efficiency 

HYBRID SENSOR 




p-n junction 




Conversion 

Point 

Spread 

Function 

Sensitvity 

Random access 



SIDECAR ASIC 

SIDECAR ASIC 


24

HgCdTe hybrid FPA cross-section (substrate removed) 

Incident 

Photons 

Bulk n-type HgCdTe 

Anti-reflection 

coating 

implanted p-type HgCdTe 

(collect holes) 

indium bump 

silicon multiplexer 

epoxy 

MOSFET input 

Output 

Signal 

25

Hybrid Imager Architecture 

HgCdTe light 

detecting material 

ROIC 

junction 

Indium 

bump 

V dd 

amp drain voltage 

Reset 

junction 

Indium 

bump 

junction 

Indium 

bump 

V reset 

reset voltage 

Column 

bus 

enable 

Bus to read out amplifier signal 

MOSFET = metal oxide semiconductor field effect transistor 

H4RG-10 

4096x4096 pixels 

10 micron pixel pitch 

HyViSI silicon PIN 

Mature interconnect technique: 

• Over 16,000,000 indium 

bumps per Sensor Chip 

Assembly (SCA) 

demonstrated 

• >99.9% interconnect yield 

Example of indium bumps 

Human Hair

Cosmic Rays and Substrate Removal 

• Cosmic ray events produce clouds of detected signal due to particle-induced flashes 

of infrared light in the CdZnTe substrate; removal of the substrate eliminates the effect 

2.5um cutoff, substrate on 1.7um cutoff, substrate on 1.7um cutoff, substrate off 

Substrate Removal Positive Attributes 

1. Higher QE in the near infrared 

2. Visible light response 

3. Eliminates cosmic ray fluorescence 

4. Eliminates CTE mismatch with silicon ROIC 

Images courtesy of Roger Smith 

27

Quantum Efficiency of substrate-removed HgCdTe 

Quantum Efficiency of 2.3 micron HgCdTe 

28

Example Anti-reflection coatings for HgCdTe 

100% 

Transmission into the HgCdTe Layer (%) 

Transmission (%) 

90% 

80% 

70% 

60% 

50% 

40% 

30% 

20% 

10% 

Single Layer (WFC3) 

Double Layer 

Three Layer (NIRCAM SWIR) 

0% 

400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 

Wavelength (nm) 

29

Dark Current 

Undesirable byproduct of light detecting materials 

Colder Temp 

Fraction of lattice 

Warmer 

Temp 

E g 

These vibrations have 

enough energy to pop 

electron out of the valence 

band of the crystal lattice 

Energy of vibration 

• The vibration of particles (includes crystal lattice phonons, electrons and holes) has 

energies described by the Maxwell-Boltzmann distribution. Above absolute zero, some 

vibration energies may be larger than the bandgap energy, and will cause electron 

transitions from valence to conduction band. 

• Need to cool detectors to limit the flow of electrons due to temperature, i.e. the dark 

current that exists in the absence of light. 

• The smaller the bandgap, the colder the required temperature to limit dark current 

below other noise sources (e.g. readout noise)

Dark Current of MBE HgCdTe 

Dark 

Current 

10 8 

10 7 

10 6 

10 5 

10 4 

Typical InSb 

Dark Current 

~9 

~5 ~2.5 

Electrons 

per pixel 

per sec 

10 3 

10 2 

10 

18 micron 

square 

1 

pixel 10 -1 

~1.7 

10 -2 

10 -3 

10 -4 30 50 70 90 110 130 150 170 190 210 230 

Temperature (K) 

HgCdTe cutoff wavelength (microns) 

31





HgCdTe, Si 



Quantum 

Efficiency 

HYBRID SENSOR 




p-n junction 




Conversion 

Point 

Spread 

Function 

Sensitvity 

Random access 



SIDECAR ASIC 

SIDECAR ASIC 


32

MOSFET Principles 

MOSFET = metal oxide semiconductor field effect transistor 

Turn on the MOSFET and 

current flows from source to 

drain 

Top view 

Source 

Gate 

Drain 

Add charge to gate & the 

current flow changes since the 

effect of the field of the charge 

will reduce the current 

Side view 

Source 

Gate 

current 

Drain 

Metal 

Oxide 

Semiconductor 

Fluctuations in current flow produce “readout noise” 

Fluctuations in reset level on gate produces “reset noise”

IR multiplexer pixel architecture 

V dd 


Photovoltaic 

Detector 

Detector 

Substrate 

Output


Reset 

V reset 

reset voltage 

V dd 


“Clock” (green) 

“Bias voltage” (purple) 

Photovoltaic 

Detector 

Detector 

Substrate 

Output


V dd 


V reset 

reset voltage 

Enable 

“Clock” (green) 

Reset 

“Bias voltage” (purple) 

Photovoltaic 

Detector 

Detector 

Substrate 

Output

General Architecture of CMOS-Based Image Sensors 

Control 

& 

Timing 

Logic 

(optional) 

Vertical Scanner 

for Row Selection 

Pixel Array 

Bias 

Generation 

& DACs 

(optional) 

A/D conversion 

(optional) 

Digital 

Output 

Horizontal Scanner 

/ Column Buffers 

Analog 

Amplification 

Analog 

Output

Reduction of noise from multiple samples 

Non-destructive readout enables reduction of noise from multiple samples 

H2RG array 

2.5 micron cutoff 

Temperature = 77K 

Measured 

Simple Theory (no 1/f noise) 

CDS = correlated double sample 

38

Pixel Amplifier Options 

39

High Performance Hybrid CMOS Arrays 

High Quality MBE HgCdTe + High Performance CMOS Design + Large Area Hybridization 

High Quality 

Detectors 

High Quantum Efficiency 

High Performance Amplifiers 

Low Dark Current 

Imaging System on Chip Architecture 

High Performance Readout Circuits

HyViSI TM – Hybrid Visible Silicon Imager 

Focal plane array performance independently verified by: 

• Rochester Institute of Technology 

• European Southern Observatory 

• US Naval Observatory & Goddard Space Flight Center 

Readout noise, at 100 kHz pixel rate 

• 7 e- single CDS, with reduction by multiple sampling 

Pixel operability > 99.99% 

41

HyViSI Array Formats 

Ground-based Astronomy (Rochester Institute of Technology) 

Mars Reconnaissance 

Orbiter (MRO) 

Crab Nebula (M1) 

NGC2683 Spiral Galaxy 

Hercules Cluster (M13) 

TCM 6604A 

640×480 pixels 

27 µm pitch 

CTIA 

1K×1K H1RG-18 

2K×2K H2RG-18 

4K×4K H4RG-10 

J-MAPS 

Astrometry 

Mission 

4K×4K 

H4RG-10 

Mosaic of 4 arrays 

TEC Package by Judson 

42

HAWAII-2RG 2048×2048 pixels 

HAWAII-2RG (H2RG) 

• 2048×2048 pixels, 18 micron pitch 

• 1, 2, 4, 32 ports 

• “R” = reference pixels (4 rows/cols at edge) 

• “G” = guide window 

• Low power:

The SIDECAR ASIC – Focal Plane Electronics on a Chip 

Replace this 

with this! 

1% volume 

1% power 

1% hassle 

SIDECAR: System for Image Digitization, Enhancement, Control And Retrieval 

44

SIDECAR ASIC – Focal Plane Electronics on a Chip 

SIDECAR ASIC 

Ground-based package 


SIDECAR ASIC package 

(for ACS Repair*) 

SIDECAR ASIC 

• 36 analog input channels 

• 36 16-bit ADCs: up to 500 kHz 

• 36 12-bit ADCs: up to 10 MHz 

• 20 output bias channels 

• 32 digital I/O channels 

• Microcontroller (low power) 

• LVDS or CMOS interface 

• Low power: 

•


Advanced Camera for Surveys Repair 

• SIDECAR ASIC used to operate the CCD 

sensors 

• New package developed 

46

Spaceflight packaging: JWST Fine Guidance Sensor 

• Package for H2RG 2048x2048 

pixel array 

• TRL-6 spaceflight qualified 

• Interfaces directly to the 

SIDECAR ASIC 

• Robust, versatile package 

• Thermally isolated FPA 

can be stabilized to 1 mK 

when cold finger 

fluctuates several deg K 

47

SIDECAR ASIC & large mosaic focal plane arrays 

2×2 5×7 

H2RG 2K×2K 

Mechanical Prototype 

4×4 

H2RG 

4x4 Mosaic 

for Space Mission 

48

Teledyne – Your Imaging Partner for Astronomy & Civil Space 

State-of-the-art & high TRL 

• CMOS Design 

• Detector Materials 

• Packaging 

• Electronics 

• Systems Engineering 

Chart 49 

Packaging 

Electronics 

Soft x-ray UV Vis Infrared 

0.4 0.7 0.9 16 

10 -4 10 -2 

HgCdTe 

μm 

Substrate-removed 

Silicon 1.1 

CMOS Design Expertise 

• Pixel amplifiers – lowest noise to highest flux 

• High level of pixel functionality (LADAR, event driven) 

• Large 2-D arrays, pushbroom, redundant pixel design 

• Hybrids made with HgCdTe, Si, or InGaAs 

• Monolithic CMOS 

• Analog-to-digital converters 

• Imaging system on a chip 

• Specialized ASICs 

• Radiation hard 

• Very low power

Teledyne 

Enabling humankind to understand the Universe and our place in it

James Beletic's presentation

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