Characterization of a Geiger-mode Avalanche
Photodiode
Chris Maloney
May 10, 2011
Project Objectives
♦ To extract key parameters that will allow for effective and
efficient operation of a Geiger-mode avalanche photodiode
array in a LIDAR imaging system
April 9, 2015
Characterization of a Geiger-Mode APD
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Project Goals
♦ Extract key parameters
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Breakdown voltage
Diode ideality factor
Series resistance
Dark count rate
Optimal bias for imaging
Number of traps present
Type of traps present
April 9, 2015
Characterization of a Geiger-Mode APD
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Applications
♦ Avalanche photodiodes (APDs) are used for light detection
and ranging (LIDAR)
Color coded video of a Chevy van
produced by Lincoln Lab LIDAR system
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Characterization of a Geiger-Mode APD
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Applications
♦ Altimetry
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Measuring rainforest canopy
Measuring polar icecaps
Mapping celestial bodies
Mapping ocean topography
♦ Autonomous Landing
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Unmanned aircrafts
Landing on Mars
Landing on an asteroid
(Image Credit: MOLA Science Team and
G. Shirah, NASA GSFC Scientific
Visualization Studio.)
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Characterization of a Geiger-Mode APD
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Background
♦ Lincoln Laboratory at
MIT has fabricated a
32x32 array of Geigermode APDs for LIDAR
imaging applications
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Characterization of a Geiger-Mode APD
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Linear-mode vs. Geiger-mode
♦ APDs can be operated in linear-mode or Geiger-mode
♦ Geiger-mode provides much more sensitivity
♦ Linear-mode can produce intensity images
M
Ordinary
photodiode
Linearmode APD
Geigermode APD
100
10
1
0
Response
I(t)
to a
photon
April 9, 2015
Breakdown
1
M
∞
(Image Credit: D.F Figer.)
Characterization of a Geiger-Mode APD
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Project Flowchart
NO
Receive
detector
Design
camera
Fabricate
camera
Light
tight?
YES
Measure
dark count
rate vs. gate
width
Write IDL
code for
performance
tests
Extract IV
parameters
Measure
dark count
rate vs. bias
Measure
dark count
rate vs. dead
time
Analyze data
April 9, 2015
Characterization of a Geiger-Mode APD
C. Maloney
Measure
diode IV
curve
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System Design
CAD camera part
April 9, 2015
Fabricated camera
Characterization of a Geiger-Mode APD
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Front View
Without the lens
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Characterization of a Geiger-Mode APD
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Readout board integrated with camera
View inside of camera
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Characterization of a Geiger-Mode APD
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Detector integrated with readout board
32x32 APD array
Readout board and detector are both from MIT’s Lincoln Laboratories
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Characterization of a Geiger-Mode APD
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System Design
Complete LIDAR system
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Characterization of a Geiger-Mode APD
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Diode IV Testing
♦ Shielded Probe Station
♦ Agilent 4156B Parameter Analyzer
♦ Noise Floor ~ 1 fA
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Characterization of a Geiger-Mode APD
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Measured Reverse Diode Current vs. Voltage
Breakdown
Voltage = 28 V
Dark Current = 0.1 pA
Dark Current Density ~ 1 nA/cm2
All diodes across the wafer are uniform
April 9, 2015
Characterization of a Geiger-Mode APD
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Measured Forward Diode Current vs. Voltage
n = 1.0
Series resistance = 2 kΩ
No R/G region
No R/G region implies number of traps are minimal
April 9, 2015
Characterization of a Geiger-Mode APD
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Gate Width Definition
♦ The amount of time the detector is ready to detect a photon
hν
Gate Width
Timing Gate
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Characterization of a Geiger-Mode APD
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Measured Dark Count Rate vs. Gate Width

NC

 ln 1 
NG






Dark count rate should be constant
April 9, 2015
Characterization of a Geiger-Mode APD
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Dead Pixels
Upper right corner is unresponsive due to low yielding bump-bonds
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Characterization of a Geiger-Mode APD
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Measured Dark Count Rate vs. Gate Width – 9 by 8 array
Dark count rate is constant and no longer decreasing
April 9, 2015
Characterization of a Geiger-Mode APD
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Measured Dark Count Rate vs. Bias
Add ~5V to x-axis to account for cathode voltage
Breakdown voltage is higher than breakdown extracted from IV curve
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Characterization of a Geiger-Mode APD
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Afterpulsing Theory
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Detector is armed and a laser pulse is detected
Detector cannot detect photons for tdead
Any carriers caught in traps will also discharge
Detector is armed
If tdead is shorter than the trap lifetime then the trap will discharge
while the detector is armed and will result in a false event
APD current
APD bias
Timing gate
Laser-induced
firing
Afterpulse
Varm
tdead
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Characterization of a Geiger-Mode APD
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Afterpulsing Model
 (t dead )  Rdark  Pa
N ft
 trap
 t dead
exp 
 
 trap
 [1]
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
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λ – dark count rate
Rdark – measured dark count rate without afterpulsing
Pa – avalanche probability
Nft – number of filled traps
tdead – dead time
τtrap – trap lifetime
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Characterization of a Geiger-Mode APD
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Measured Afterpulsing
♦ No afterpulsing
seen
No traps
or
Trap lifetime
>500 μs
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Characterization of a Geiger-Mode APD
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Acknowledgements
♦ Rochester Imaging Detector Lab
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Dr. Don Figer
John Frye
Dr. Joong Lee
Brandon Hanold
Kim Kolb
♦ Microelectronic Engineering Department
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Dr. Rob Pearson
Dr. Sean Rommel
Dr. Karl Hirschman
♦ This work has been supported by NASA grant
NNX08AO03G
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References
[1] K.E. Jensen, “Afterpulsing in Geiger-mode avalanche
photodiodes for 1.06 μm wavelength” Lincoln Laboratory,
MIT 2006.
[2] D. Neamen, “An Introduction to Semiconductor Devices”
McGraw Hill 2006.
[3] R.F. Pierret, “Semiconductor Device Fundamentals”
Addison-Wesley Publishing Company, Inc. 1996.
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