MIT LL No. MS-43282, ESC No. 09-1097

Zero Read Noise Detectors for the TMTDon Figer, Brian Ashe , John Frye, Brandon Hanold, Tom Montagliano, Don Stauffer (RIDL), Brian Aull, Bob Reich, Dan Schuette, Jim Gregory, Erik Duerr, Joseph Donnelly (MIT/LL)

MIT LL No. MS-43282, ESC No. 09-1097

2

Outline

• Motivation– Why pursue photon-counting technology?– Why use Geiger-mode avalanche photodiodes

(APDs)?• Moore Detector for TMT• Heritage: LIDAR• Conclusions

3

Outline



4

Why pursue photon-counting technology?• Photon-counting detectors effectively have

zero read noise.• In low light applications, read noise can

dominate signal-to-noise ratio.• Many applications can become low light

applications with higher resolutions.– spectroscopy– time-resolved photometry– fast wavefront sensing and guiding

5

Detectivity (higher is better)

.)(411

2yDetectivit

1ysensitivit

1yDetectivit

1SNRat which flux y Sensitivit

noise) read(noise)dark (flux backgroundflux signal

flux signal

dominated noise read

2,

1,

2,

2,

22

pixreadreaddarkbackgroundpix

SNR

readpixdarkpixbackgroundpix

readdarkbackinstinst

inst

nN

tQE

NtitQENntQE

N

NntintQENntQEN

tQEN

NtitQEFh

AtQEFh

A

tQEFh

A

NSSNR

6

Exposure Time to SNR=1

.

)(2

)(4)()(

for t.equation SNR Solve SNR. particular areach to timeexposure

0 and 0 and 1

2

222,

4,

2

,

QEN

nN

QEN

SNRNQEnNinQENnQENSNRinQENnQENSNR

pixreadiNSNR

readpixdarkpixbackgroundpixdarkpixbackgroundpix

darkbackground

7

Example for Planet Imaging

• The exposure time required to achieve SNR=1 is dramatically reduced for a zero noise detector compared to detectors with state of the art read noise.

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%0 6,600 2,300 1,311 900 680 544 453 388 338 300 1 7,159 2,674 1,591 1,123 865 703 591 510 448 400 2 8,486 3,457 2,141 1,547 1,209 992 841 730 645 577 3 10,148 4,363 2,760 2,016 1,587 1,309 1,113 968 857 768 4 11,954 5,312 3,402 2,500 1,976 1,633 1,392 1,212 1,074 964 5 13,830 6,281 4,053 2,990 2,369 1,961 1,673 1,459 1,293 1,161 6 15,745 7,259 4,709 3,484 2,764 2,291 1,956 1,706 1,513 1,359 7 17,684 8,244 5,368 3,979 3,161 2,621 2,239 1,954 1,734 1,558

read

noi

se

mag_star=5, mag_planet=30, R=100, i_dark=0.0010

Exposure Time (seconds) for SNR = 1

FOM Quantum Efficiency

8

Why use Geiger-Mode Avalanche Photodiodes (GM-APDs)?• produce easily distinguishable high voltage

pulse per photon• have zero “excess noise factor”• allow for hybridization and bonding to non-

optical detecting materials• allow photon counting inside each pixel for

high frame rates and time tagging• have demonstrated excellent performance for

LIDAR applications

9

Gain of an APD

1

10

100

M

Breakdown0

Ordinary photodiode

Linear-mode APD

Geiger-mode APD

Response to a photon M1

∞ I(t)

10

Geiger-Mode Imager: Photon-to-Digital Conversion

Quantum-limited sensitivityNoiseless readout Photon counting or timing

APD

Digitaltimingcircuit

Digitallyencodedphotonflight time

photon

Lensletarray

APD/CMOS array

Focal-plane

Pixel circuit

11

Outline



12

Moore Detector Project Goals• Operational

– Photon-counting– Wide dynamic range: flux limit to 108 photons/pixel/s– Streaming readout

• adaptive optics imaging • multiple target tracking

– Time delay and integrate• Technical

– Backside illumination for high fill factor– Demonstrate 25 m pitch imager with streaming, single

photon, readout

13

Moore Photon Counting ImagerOptical (Silicon) Detector Performance

Parameter Phase 1 Goal

Phase 2 Goal

Format 256x256 1024x1024Pixel Size 25 µm 20 µmRead Noise zero zeroDark Current (@140 K) <10-3 e-/s/pixel <10-3 e-/s/pixelQEa Silicon (350nm,650nm,1000nm) 30%,50%,25% 55%,70%,35%Operating Temperature 90 K – 293 K 90 K – 293 KFill Factor 100% 100%aProduct of internal QE and probability of initiating an event. Assumes

antireflection coating match for wavelength region.

14

Moore Photon Counting ImagerInfrared (InGaAs) Detector PerformanceParameter Phase 1

Goal Phase 2

GoalFormat Single pixel 1024x1024Pixel Size 25 µm 20 µmRead Noise zero zeroDark Current (@140 K) TBD <10-3 e-/s/pixelQEa (1500nm) 50% 60%Operating Temperature 90 K – 293 K 90 K – 293 KFill Factor NA 100% w/o lensaProduct of internal QE and probability of initiating an event. Assumes

antireflection coating match for wavelength region.

15

Moore Detector Project Status

• A 256x256x25m readout integrated circuit is being fabricated.

• InGaAs test diodes are being fabricated.• Silicon GM-APD arrays have been fabricated and will

be bump-bonded to the new readout circuit.• Photon-counting electronics are being built.• Testing will begin later in 2009.• Depending on results, megapixel silicon or InGaAs

arrays will be developed.

16

Overview of Pixel OperationPixel Architecture

17

ROIC Pixel Layout (2x2 pixels)

2 pixels, 50 m

2 pixels, 50 m

metal bump bond pad

core(active quench, discriminator, APD latch)

counter rollover latch

counters (4 pixels)

18

InGaAs Development

• 3 APD designs grown and fabricated– 2-m-wide avalanche region (all InP)– 3-m-wide avalanche region (all InP)– 2-m-wide avalanche region (InGaAs absorber)

• Room-temperature CV measurements made• Devices in packaging for low temperature

measurements

19

Outline



20

Si APD/CMOS Development History

1996 2009

APD’s Discrete 4x4 arrays

4x4 arrays wire bonded to

16-channel CMOS readout

32x32 arraysfully integrated with 32x32 CMOS readout

64 x 64 arrays 3D-integrated with 2 tiers of SOI CMOS 256 x 256 arrays

not to scale

21

• Imaging system photon starved. Each detector must precisely time a weak optical pulse.

Microchip laser

Geiger-mode APD array

Color-codedrange image

LIDAR Imaging System

22

A LIDAR Imaging Detector for NASA Planetary Missions

• These arrays will be fabricated for back-illumination with bump bonding, enabling high performance in a space-qualifiable focal plane.

• The design of the ROIC will be finished by the end of 2009, with fabrication starting in early 2010.

• Funding: $546,000 • Duration: 3 years (2008-2010)

Low field

High fieldmultiplier

Medium low field

absorber

Parameter Current Goal

Space-Qualifiable NO YES

Scalable to Large Format NO YES

CMOS ROIC Timing Resolution 250 ps 250 ps

Pixel Size 50 m 50 m

Multiplied Dark Current (@14 K) unknown <10-3 e/s/pixel

QE (350nm,650nm,1000nm)a 45%,65%,5% 45%,65%,10%

Operating Temperature 293 K 90 K – 293 K

Radiation Limit unknown 50 Krad(Si)b

Technology Readiness Levelc 2 4

23

32x32 APD/CMOS Array with Integrated GaP Microlenses

24

Laser Radar Brassboard System (Gen I)

• 4 4 APD array• External rack-mounted timing circuits• Doubled Nd:YAG passively Q-switched microchip laser

(produces 30 µJ, 250 ps pulses at = 532 nm)• Transmit/receive field of view scanned to generate 128 128 images

Taken at noontime on a sunny day

25

Conventional vs LIDAR Image

Conventional image

26

3D Imaging of Model Airplane

• Multiple-frame coincidence processing of ~3-4 frames removes isolated dark counts

• Image quality excellent due to low optical cross-talk between pixels

Airplane hanging on 6 mm rope

Color-code:1 m range display

3D Display of Processed Image,Probability of Detection Color-code

Single Frame

27

Rotatable 3D Images of Multiple Objects

• 128x128 images recorded with scanned 4x4 array at 1.06 m• Coincidence processed to remove background/dark counts• Dark blue equivalent to <2 photon average return (right image)

Color-coded by Distance Color-coded by Detection Probability

28

Outline



29

Conclusions

• Large-format photon-counting imaging detectors are within reach.

• We are funded to make 256x256 and megapixel devices.

• A 256x256 detector silicon-based array should be in testing by the end of the year.

• The devices will be implemented in a broad range of low light level and LIDAR timing applications.

MIT LL No. MS-43282, ESC No. 09-1097

Documents