High Performance Imaging Sensors for Astronomy & Civil Space 18 March 2010 James W. Beletic

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

NICMOS, WFC3, ACS Repair

Rosetta

Mars Reconnaissance Orbiter

WISE

Bands 1 & 2

Deep Impact & EPOXI

JWST

NIRCam, NIRSpec, FGS

J-MAPS

1st CMOS for astronomy

New Horizons

JDEM Lander (çiva)

CRISM (Vis & IR)

IR spectrograph

IR spectrograph

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) • 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)

6.5m mirror

JWST will find the “first light” objects after the Big Bang, and will study how galaxies, stars and planetary systems form

Earth

SIDECAR ASIC Focal Plane Electronics 15 ASICs will operate in JWST One ASIC per H2RG array

NIRCam (Near Infrared Camera)

sunshield

NIRSpec

FGS (Fine Guidance Sensors)

3 individual MWIR 2Kx2K

• Acquisition and guiding • Images guide stars for telescope stabilization • Canadian Space Agency

(Near Infrared Spectrograph)

1x2 mosaic of MWIR 2Kx2K

Two 2x2 mosaics

• Spectrograph • Measures chemical composition, temperature and velocity • European Space Agency / NASA

of SWIR 2Kx2K

Two individual MWIR 2Kx2K

• Wide field imager • Studies morphology of objects and structure of the universe • U. Arizona / Lockheed Martin

All Sensors Delivered ASIC deliveries to be completed in June 2010 6

NASA’s Partner for Earth Science NPOESS

LDCM

CHANDRAYAAN-1

CrIS

TIRS

GLORY

GOES-R

Moon Mineralogy Mapper (Vis-IR)

EO-1 (SWIR)

ABI (LWIR)

AURA OCO-R Tropospheric Emission Spectrometer IR FT Spectrometer

Orbiting Carbon Observatory (Vis & IR)

LEISA Atmospheric Corrector (IR arrays)

Visible to 16.5 microns 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

Sensor Chip Assembly Focal Plane 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 Launch from Satish Polar Satellite Launch Vehicle 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: • O2A band at 0.758-0.772 µm • weak CO2 band at 1.594 -1.619 µm • strong CO2 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

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The Technologies of High Performance Imagers

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Energy of a photon

• •

Wavelength (μm)

Energy (eV)

Band

0.3

4.13

UV

0.5

2.48

Vis

0.7

1.77

Vis

1.0

1.24

NIR

2.5

0.50

SWIR

5.0

0.25

MWIR

10.0

0.12

LWIR

20.0

0.06

VLWIR

Energy of photons is measured in electron-volts (eV) eV = energy that an electron gets when it “falls” through a 1 volt field.

1 eV = 1.6 • 10-19 J (J = joule)

An electron-volt (eV) is extremely small

1 J = N • m = kg • m • sec-2 • m 1 kg raised 1 meter = 9.8 J = 6.1 • 1019 eV •• The The energy energy of of aa photon photon is is VERY VERY small small –– Energy Energy of of SWIR SWIR (2.5 (2.5 μm) μm) photon photon is is 0.5 0.5 eV eV

•• In In 55 years, years, JWST JWST will will take take ~1 ~1 million million images images 15 H2RG 2K×2K arrays 63 million pixels

–– 1000 1000 sec sec exp., exp., 15 15 H2RGs, H2RGs, 90% 90% duty duty cycle cycle 10photons –– Photons Photons // H2RG H2RG image image ≈≈ 3.6 3.6 ×× 10 1010 photons •• •• •• ••

–– ––

5% 5% pixels pixels at at 85% 85% full full well well 10% 10% "" at at 40% 40% full full well well 10% 10% "" at at 10% 10% full full well well 75% 75% "" at at 1% 1% full full well well

Full well 85,000 e-

16 Total Total ## SWIR SWIR photons photons detected detected ≈≈ 3.6 3.6 ×× 10 1016 16 eV Total Total energy energy detected detected ≈≈ 1.8 1.8 ×× 10 1016 eV

•• Drop Drop peanut peanut M&M M&M®® candy candy (~2g) (~2g) from from height height of of 15 15 cm cm (~6 (~6 inches) inches) 16 eV –– Potential Potential energy energy ≈≈ 1.8 1.8 xx 10 1016 eV

15 15 cm cm peanut peanut M&M M&M®® drop drop is is equal equal to to the the energy energy detected detected during during 55 year year operation operation of of the the James James Webb Webb Space Space Telescope! 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

HYBRID SENSOR CHIP ASSEMBLY (SCA)

Anti-reflection coating Substrate removal

1. Light into detector

Detector Materials HgCdTe, Si

2. Charge Generation

Electric Fields in detector collect electrical charge p-n junction

3. Charge Collection

Source follower

4. Charge-to-Voltage Conversion

Random access or full frame read

SIDECAR ASIC

Point Spread Function

Sensitvity

Quantum Efficiency

5. Signal Transfer

6. Digitization

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Crystals are excellent detectors of light •

Simple model of atom – Protons (+) and neutrons in the nucleus with electrons orbiting

•

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.

• • Silicon crystal lattice

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

Detector Families Si - IV semiconductor HgCdTe - II-VI semiconductor InGaAs & InSb - III-V semiconductors

VI

Tunable Wavelength: Unique property of HgCdTe Hg1-xCdxTe

Modify ratio of Mercury and Cadmium to “tune” the bandgap energy

E g = −0.302 + 1.93 x − 0.81 x + 0.832 x + 5.35 × 10 T (1 − 2 x ) 2

3

−4

G. L. Hansen, J. L. Schmidt, T. N. Casselman, J. Appl. Phys. 53(10), 1982, p. 7099 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) 2 3 4

63.2% of light absorbed 86.5% 95.0% 98.2%

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

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Molecular Beam Epitaxy (MBE) Growth of HgCdTe

RIBER 3-in 3-in MBE MBE Systems Systems RIBER

3 inch diameter platen allows growth on one 6x6 cm substrate

RIBER RIBER 10-in 10-in MBE MBE 49 49 System 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) Short-wave infrared (SWIR) Mid-wave infrared (MWIR)

1.75 µm 2.5 µm 5.3 µm

J,H J,H,K J,H,K,L,M

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6 Steps of CMOS-based Optical / IR Photon Detection 1. Light into detector

Detector Materials HgCdTe, Si

2. Charge Generation

Quantum Efficiency

Electric Fields in detector collect electrical charge p-n junction

3. Charge Collection

Source follower

4. Charge-to-Voltage Conversion

Random access or full frame read

Point Spread Function

Sensitvity

HYBRID SENSOR CHIP ASSEMBLY (SCA)

Anti-reflection coating Substrate removal

5. Signal Transfer

SIDECAR ASIC

SIDECAR ASIC

6. Digitization

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HgCdTe hybrid FPA cross-section

(substrate removed)

Incident Photons Anti-reflection coating Bulk n-type HgCdTe

implanted p-type HgCdTe (collect holes) epoxy

indium bump

silicon multiplexer

MOSFET input

Output Signal

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Hybrid Imager Architecture HgCdTe light detecting material junction

junction

junction

Indium bump

Indium bump

Indium bump

ROIC

Vdd amp drain voltage

Reset

Vreset 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:

Example of indium bumps

• Over 16,000,000 indium

•

bumps per Sensor Chip Assembly (SCA) demonstrated >99.9% interconnect yield

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. 2. 3. 4.

Higher QE in the near infrared Visible light response Eliminates cosmic ray fluorescence Eliminates CTE mismatch with silicon ROIC Images courtesy of Roger Smith

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Quantum Efficiency of substrate-removed HgCdTe Quantum Efficiency of 2.3 micron HgCdTe

28

Example Anti-reflection coatings for HgCdTe

Transmission into the HgCdTe Layer (%) Transmission (%)

100% 90% 80% 70% 60% Single Layer (WFC3)

50%

Double Layer

40%

Three Layer (NIRCAM SWIR) 30% 20% 10% 0% 400

600

800 1000 1200 1400 1600 1800 2000 2200 2400 2600 Wavelength (nm)

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Dark Current

Fraction of lattice

Undesirable byproduct of light detecting materials Colder Temp

Eg Warmer Temp

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 108 107

Typical InSb Dark Current

~9

~5

106

Dark Current Electrons per pixel per sec 18 micron square pixel

~2.5

105 104 ~1.7

103 102 10 1 10-1 10-2 10-3 10-4 30

50

70

90

110

130

150

170

190

210

230

Temperature (K) HgCdTe cutoff wavelength (microns) 31

6 Steps of CMOS-based Optical / IR Photon Detection 1. Light into detector

Detector Materials HgCdTe, Si

2. Charge Generation

Quantum Efficiency

Electric Fields in detector collect electrical charge p-n junction

3. Charge Collection

Source follower

4. Charge-to-Voltage Conversion

Random access or full frame read

Point Spread Function

Sensitvity

HYBRID SENSOR CHIP ASSEMBLY (SCA)

Anti-reflection coating Substrate removal

5. Signal Transfer

SIDECAR ASIC

SIDECAR ASIC

6. Digitization

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MOSFET Principles MOSFET = metal oxide semiconductor field effect transistor

Drain

Gate

Source

Turn on the MOSFET and current flows from source to drain

Top view Side view

Metal

Gate Source

Add charge to gate & the current flow changes since the effect of the field of the charge will reduce the current

Drain

Oxide Semiconductor

current Fluctuations in current flow produce “readout noise” Fluctuations in reset level on gate produces “reset noise”

IR multiplexer pixel architecture

Vdd

amp drain voltage

Photovoltaic Detector Detector Substrate

Output

IR multiplexer pixel architecture

Vreset

reset voltage

“Clock” (green) Vdd

amp drain voltage

Reset

“Bias voltage” (purple)

Photovoltaic Detector Detector Substrate

Output

IR multiplexer pixel architecture Vdd

amp drain voltage

Vreset

Enable

reset voltage

“Clock” (green) “Bias voltage” (purple)

Reset

Photovoltaic Detector Detector Substrate

Output

Control & Timing Logic

Vertical Scanner for Row Selection

General Architecture of CMOS-Based Image Sensors

Pixel Array

Bias Generation & DACs (optional)

A/D conversion (optional) Digital

(optional)

Output

Horizontal Scanner / Column Buffers

Analog Analog Amplification 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

Low Dark Current

High Performance Amplifiers

Imaging System on Chip Architecture

High Performance Readout Circuits

HyViSITM – 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)

Crab Nebula (M1)

NGC2683 Spiral Galaxy

Mars Reconnaissance Orbiter (MRO)

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

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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: