Radiation effects on
optoelectronic
components and systems
Karl Gill
CERN, CMS Experiment
Outline

1: Introduction
 1.1:
Technologies
 1.2: LHC radiation environments
 1.3: Review of radiation damage mechanisms

2: Radiation damage effects
 2.1:
Components
 2.2: System implications
K. Gill
Optoelectronics

Photonics - The technology of generating and
harnessing light and other forms of radiant
energy whose quantum unit is the photon”
– definition from Photonics Magazine

Applications:
 Communication
 Imaging
 Sensing
 Information
K. Gill
display
LHC Opto-applications

Widespread use of optoelectronics and
(fibre-)optics at LHC
 readout
and control optical links
 monitoring and calibration
 alignment
K. Gill
Technologies

Many device technologies and materials
- lasers, LEDs, (modulators),….
 Receivers - Photodiodes, CCDs, [APD], .…
 Passive components - fibres, lenses,….
 [Switches - optocouplers]
 Transmitters

K. Gill
Materials include: Si, GaAs, InGaAs, InGaAsP, InP,
SiO2
Active materials
Emitters
Detectors
Ref [1]
K. Gill
COTS issues

COTS in many LHC systems
 Benefit
from industrial developments
 cheaper,
 However
 no

K. Gill
“reliable” devices
COTS not made for LHC environment
guarantees of long-life at LHC
validation testing of COTS is mandatory
Radiation damage overview
Radiation Environment
Interaction of radiation with material
Ionization
Displacement
SEU
Defect creation
Component
Effects
Effects at system level
K. Gill
Annealing
Environments

Optoelectronics already employed in variety
of harsh radiation environments

e.g. civil nuclear and space applications
Total 1E+8
dose
(Gy) 1E+6
Space (p,e)
Nuclear
(g, also n)
1E+4
1E+2
1E+0
1E-2
1E-2
Ref [2]
K. Gill
1E+0
1E+2
1E+4
1E+6
Dose rate (Gy/hr)
LHC Radiation environments: experiments

K. Gill
e.g CMS neutrons
(courtesy M. Huhtinen)
LHC Radiation environments: experiments

K. Gill
e.g CMS photons
(courtesy M. Huhtinen)
Radiation damage mechanisms

Displacement
Ionization
Transient

also annealing


K. Gill
Displacement damage


e.g. displacement
cascade of 30keV
Si recoil
most NIEL in last
5kEV
 final
Ref [3]
K. Gill
cluster of
defects
 ~100Å size
 high defect density
in crystal lattice
defects in band-gap


can cause several
effects
depends upon:
 position
in band
gap
 type of defect
 donor/acceptor
 single
or multiple
levels
K. Gill
Ref [4]
generation-recombination at defects
Emission and capture transitions
via defect state in band-gap
Ec
ET
Ev



1
v th N T
(for defect at mid-gap)
Carrier lifetime:
generally, most damaging defects near centre of band-gap
K. Gill
Ref [1]
Lifetime degradation

Radiation damage introduces more defects
NT (F)  NT (0)  KF



(assume linear)
K is ‘damage factor’ - depends on particle type, energy
F is fluence
lifetime therefore decreases with fluence (or dose)
1
1
  KF
F 0
or
K. Gill
0
 1  K0 F
F
(Messenger eqn)
Ref [5]
Non-ionizing energy loss

dependence upon particle type and energy

Damage factors (K)
related to NIEL
Ref [6]
K. Gill
Ionization damage
Ref [4]
K. Gill
Ionization damage effects

K. Gill
charge trapped in oxide or at interface
Ref [7]
Defects in glasses

defects (‘colour centres’) created by irradiation
 bonds

K. Gill
broken by ionisation/displacement
defects absorb/scatter incident photons
Ref [8]
Transients

Single-event upsets (SEU)

passage of energetic particlecauses ionization
 primary
from charged particle or heavy ion
 secondary ionisation from recoiling nucleus

Variety of effects:
of individual ‘bits’
 can kill a component!
 corruption
K. Gill
Transient ionization

ionizing energy deposition (e.g. for Si, 40MeV p+)



large direct
ionization peak
recoils also
contribute
Ionization pulses cause SEU
Ref [9]
K. Gill
Summary of issues at LHC

Many types of optical and optoelectronic
components in LHC systems
 various
radiation environments: TK---->cavern
 Spectrum of damage effects from total dose,
fluence, SEU

Next step to look at effects in more detail
 concentrate
sources
K. Gill
on LHC R&D and other relevant
Outline

1: Introduction
 1.1:
Technologies
 1.2: LHC radiation environments
 1.3: Review of radiation damage mechanisms

2: Radiation damage effects
 2.1:
Components
 2.2: System implications
K. Gill
Component sensitivity
Device
Displacement
Total Dose
SEU
Transmitters
LED
LD
Receivers
PD
APD
CCD
Switches
Optocouplers
Optics
Fibres
Connectors
Lens
Danger!!
K. Gill
Beware
Probably OK!
Transmitters

LEDs
Edge-emitting lasers
Surface emitting lasers

(modulators)


K. Gill
Increasing
rad-hardness
Basic LED structure


P-n diode
Light from
spontaneous
emission
(recombination)
Ref [10]
K. Gill
pigtailed LED


Multi-mode
fibre pigtail
‘butt-coupled’
for optimum
efficiency
Ref [10]
K. Gill
LED characteristic

K. Gill
LED Light-current and current-voltage before/after irradiation
Ref [11]
LED damage: 1

damage vs fluence
 Significant
damage at low
particle
fluences
Ref [12]
K. Gill
LED damage: 2

damage vs fluence - e.g. different LED types

Biasing
increases
resistance
 enhances
annealing
K. Gill
Ref [12]
LED damage: 3

damage vs fluence (ATLAS SCT)
Ref [13]
K. Gill
Transmitters



K. Gill
LEDs
Edge-emitting lasers
Surface emitting lasers
Increasing
rad-hardness
Edge-emitting laser


stripe geometry
cleaved ends form Fabry-Peror optical cavity
Ref [14]
K. Gill
DCPBH-MQW

Ref [15]
K. Gill
e.g. double-channelplanar-buriedheterostructure type
Laser characteristics
1310nm DCPBH-MQW before/after pion irradiation

Main effects
Ithr
Eff
Rs
Vthr

Ep330MeV, Fp=2x1014p/cm2
K. Gill
Ref [16,17]
increase
decrease
same
increase
Damage picture
undoped InGaAsP
MQW structure
n-type
InP
defect
levels
Ec
p-type
InP
nr
sp
st
Ev

non-radiative recombination at defects
 competes
K. Gill
with laser recombination
Different vendors

Ithr and Eff changes vs neutron fluence

similar effects in all 1310nm InGaAsP lasers
K. Gill
Ref [17]
Different particles
DIthr vs fluence of different particles
threshold increase, DIthr (mA)

50
40
30
+
330MeV p
+
24GeV p (mean)
0
~6MeV n
0
0.75MeV n (mean)
Ref [16]
20
10
0
0.0
1.0
2.0
3.0
14
4.0
5.0
2
fluence, F (10 /cm )

K. Gill
Damage correlated to NIEL? probably….
Annealing (temperature)
damage anneals (faster at higher temperature)
unannealed fraction of defects

0.90
0.80
0.70
0.60
293K
313K
333K
353K
0.50
0.40
0.30
1

K. Gill
10
100
annealing time (hours)
Note: tracker operating at -10C
Ref [18]
Annealing (current)

damage anneals faster at higher forward bias
remaining damage, DIthr(t)/ DIthr(F)
0.90
0.80
0.70
dc bias
0
60mA
80mA
100mA
0.60
Ref [18]
0.50

K. Gill
1
10
annealing time, t (hrs)
100
“recombination enhanced annealing” (?)
Reliability


irradiated device lifetime > 10 years??
Ageing test at 80C
time in oven - 2nd batch (hrs)
laser threshold current, Ithr (mA)
0
1000
2000
3000
4000
60

50
40
30

20
10
K. Gill
unirrad (batch 1) (10LD)
neutron irrad (batch 1) (10 LD)
neutron irrad (batch 2) (20 LD)
0
1000
2000
3000
4000
time in oven - 1st batch (hrs)
Ref [19]

No additional
degradation in
irradiated lasers
acc. Factor ~400
relative to -10C
operation
lifetime >>10years
Other EEL parameters

includes:
 wavelength
 facet
reflectivity
 beam profile
 series resistance
 turn-on time

K. Gill
NOT affected up to 100kGy or 1015n/cm2 (1MeV)
Transmitters



K. Gill
LEDs
Edge-emitting lasers
Surface emitting lasers
Increasing
rad-hardness
VCSEL structure

surface emitting laser diode

Very small active volume
K. Gill
Ref [15]
VCSEL damage effects: 1
3.5
V
V
300
L (pre-irrad)
14
2
L (6x10 n/cm )
3.0
250
2.5
200
2.0
150
1.5
100
1.0
50
0.5
0
0.0
0
2
4
6
current, I (mA)

8
Ref [20]
Similar damage effects as in edge-emitters
 smaller
K. Gill
voltage, V (V)
output light power, L (µW)
350
absolute changes - smaller device volume
6
5
4
3
Ref [20]
K. Gill
threshold current, Ithr (mA)
0
2.5
5
14
2
neutron fluence, F (10 n/cm )
6
efficiency loss, E(F)/E(0)
threshold current, Ithr (mA)
VCSEL : 2
1

0.9
0.8
 (~6MeV
0.7
0.6
0
2.5
5
14
2
neutron fluence, F (10 n/cm )
5

4
3
0
100
200
annealing time, tr (hrs)
Damage vs
fluence
n)
 Siemens
devices
25% annealing at
room T after
irradiation
VCSEL : 3
ATLAS measurements

Ref [21]

K. Gill
Before + after 2.9x1015n/cm2 (~1MeV n) !!
VCSEL: 4

lifetime (reliability) of irradiated devices:
Ref [22]

K. Gill
Equivalent to 3700 LHC-years at 20mA !
Transmitter damage summary
Displacement
damage
Non-radiative
Defects in
band-gap
Non-radiative carrier lifetime
recombination degradation
radiative
1
1
  KF
F 0
NR
R
g



Competition between radiative
and non-radiative transitions
K. Gill

LED
EEL
VCSEL
Increasing
rad-hardness
Components review
 Transmitters
(lasers, LED’s, - total dose, fluence)
 Receivers (Photodiodes, APD, CCD)
 Passive Components (Fibres, lenses)
 Other components (Optocouplers)
K. Gill
Recievers

total fluence effects
 p-i-n
photodiode (InGaAs and Si)
 CCD’s
 [APD’s

K. Gill
see notes]
SEU effects in receivers
Optical detectors



K. Gill
Many types of
material used
cover different
wavelength
spectra
look at GaInAs
and Si
Ref [1]
p-i-n photodiode

Basic structure
Ref [1]
K. Gill
p-i-n operation

Operation principles
Ref [1]
K. Gill
InGaAs p-i-n characteristics





K. Gill
Increase in Ileak
decrease in Iphoto
Output current vs
incident power
InGaAs p-i-n -5V
before/after
2x1014p/cm2
Ref [17]
p-i-n damage picture
generation
leakage current
K. Gill
trapping +
recombination
signal loss
Different vendors - leakage
leakage current (InGaAs, 6MeV neutrons)
leakage current, Ileak (A)

10
10
10
-6
Epitaxx (Italtel)
Lucent
Alcatel
Epitaxx
Nortel
Fermionics
-7
all devices, -5V
10

-5
-8
0.1
1
14
2
neutron fluence, F (10 n/cm )
10
Ref [16]
similar damage over many (similar) devices
K. Gill
Different vendors - response

Photocurrent (InGaAs, 6MeV neutrons)
 Significant
differences
in damage
 depends mainly if front
or back-illuminated
Ref [16]
K. Gill
Front-illum. vs back-illum.

electron hole pairs created at InGaAs/InP interface
in back-illuminated diodes
absorption: g  eh
1.0
0.0


holes must travel
through InGaAs in
back-illum. p-i-n
holes travel less
distance in frontilluminated p-i-n.
n+
i (actually n-)
p+
preirradiation
after high
hadron
fluence
g
i (becomes p-)
p+
n+
g
hole
electron
charged acceptor
Defects: acceptor type
(good hole traps)
K. Gill
Different particles (leakage)

leakage current (InGaAs, different particles, 20C)
-4
10
-5
Ileak (A)
10
-6
10
330MeV p
24GeV p
~6MeV n
all at -5V
-7
10
-8
10
13
10

14
10
-2
fluence (cm )
higher energy p, p more damaging than n
K. Gill
15
10
Ref [17]
Different particles (response)
different particles:
IPC / IPC(0) @ 100µW

1.0
0.8
0.6
0.4
0.2
10

330MeV p
24Gev p
~6MeV n
all at -5V
13
14
10
-2
fluence (cm )
higher energy p, p more damaging than n
K. Gill
10
15
Ref [17]
InGaAs p-i-n annealing
After pion irradiation (room T, -5V)


1.0
1.00
0.9
0.8
0.1
after 330MeV p
leakage
photocurrent
all at -5V
1
10
Annealing time (hrs )
Leakage anneals a little
No annealing of response
K. Gill
0.98
0.96
100
relative Iphoto anneal [Iphoto(t)/Iphoto(F)]
relative Ileak anneal [Ileak(t)/Ileak(F)]

Ref [17]
InGaAs p-i-n reliability


irradiated device lifetime > 10 years??
Ageing test at 80C
normalized photocurrent, Ipc(t)/Ipc(0)
time in oven - 2nd group (hrs)
0
1000
2000
3000
1.04
4000

1.02
1.00
0.98
unirrad control (group 1)
irrad (group 1)
irrad (group 2)
0.96
0
1000
2000
3000
time in oven - 1st group (hrs)
K. Gill

No additional
degradation in
irradiated p-i-n’s
lifetime >>10years
4000
Ref [19]
ATLAS Si p-i-n damage



35% loss of
response
Ileak ~60nA (20C)
rise time still < 2ns
Ref [21]
K. Gill
ATLAS Si p-i-n reliability

ATLAS SCT Si p-i-n ageing
Ref [23]

No degradation, lifetime ~ 2720years ! (90%CL)
K. Gill
Recievers

focus on total fluence effects
 InGaAs
p-i-n photodiode
 Si p-i-n photodiode
 CCD’s
 APD’s

K. Gill
then look at SEU in control link receivers
CCD’s

Basic structure and operation
Ref [24]
K. Gill
CCD leakage

leakage current increase
Ref [25]
K. Gill
CCD leakage spikes

variations in leakage density
Ref [25]

K. Gill
linked to small size of pixels
CCD RTS

Random telegraph: unstable switching of leakage current
Ref [25]
K. Gill
CCD CTI

charge transfer inefficiency
Ref [25]
K. Gill
detector bulk-damage summary
generation
leakage current
K. Gill
trapping +
recombination
signal loss
APD’s

Basic structure
Ref [1]
K. Gill
APD damage (gain)

Effect of irradiation on gain (CMS ECAL)
F = 2x1013 (1MeV
equivalent) n/cm2
Ref [26]
K. Gill
APD damage (quant. eff.)

Damage to quantum efficiency (CMS ECAL)
F = 2x1013 (1MeV
equivalent) n/cm2
Ref [26]
K. Gill
Recievers

focus on total fluence effects
 InGaAs
p-i-n photodiode
 Si p-i-n photodiode
 CCD’s
 APD’s

K. Gill
then look at SEU in control link receivers
PD SEU

photodiodes sensitive to SEU
Ref [27]

strong dependence upon particle type and angle
K. Gill
PD SEU bit-errors

photodiodes sensitive to SEU
Ref [27]

Can change ‘0’ to a ‘1’ if signal above threshold at the time of decision
K. Gill
PD BER test

incident radiation
test setup
Optical
attenuator
1310nm laser
transmitter
single-mode
optical fibre
p-i-n
receiver
Optical
powermeter
output
signal
bit-error-rate tester
input
signal
Ref [28]

Photodiode and receiver chip irradiated
K. Gill
PD BER: 1


BER with 59MeV protons in InGaAs p-i-n (D=80mm)
90 angle 1-100mW optical power
10
Bit-error-rate
10
10
10
10
10
10
0

CERN
-2
+
p (beam off)
-4
+
p (59MeV, 90°)
-6
-8

-10
long ionizing track in
active layer of p-i-n
direct ionization effect
Ref [28]
-12
-40
-35
-30
-25
-20
-15
-10
Optical power amplitude at PD (dBm)
K. Gill

large BER up to
high power
PD BER: 2


BER with 59MeV protons (cont.)
smaller angles
10
Bit-error-rate
10
10
10
10
10
10
+
0
p (beam off)
+
p (59MeV, 90°)
-2
+

p (59MeV, 45°+)
-4
+
p (59MeV, 30°+)
+
p (59MeV, 10°+)
-6

-8
-10

-12
-30
-25
-20
-15
lower BER at
lower angles
shorter ionizing
track in active
volume of p-i-n
nuclear recoil
effect
-10
Optical power amplitude at PD (dBm)
Ref [28]
K. Gill
PD BER: 3

energy deposition (e.g. for Si with 40MeV p+)


large direct
ionization peak
recoils contribute
individual events
with large energy
deposition
Ref [9]
K. Gill
PD BER: 4

compare BER for 59MeV p+ and 62MeV n0
10
+
p (59MeV, 45°) 
2
Bit-error cross section (cm )
+
p (59MeV, 90°)
-4
+
p (59MeV, 30°)
10
-6
+
p (59MeV, 10°)
0
n (60MeV, 90°)
10
10

0
n (60MeV, 45°)
-8
-10


10
-12

-30
-25
-20
-15
-10
Neutrons give
nuclear recoils
same collision Xsection as for
protons
BER=Nerrors/F
BER(n) = BER(p)
confirms nuclear
recoil effect for p+
Optical power amplitude at PD (dBm)
Ref [28]
K. Gill
Components review
 Transmitters
(lasers, LED’s, - total dose, fluence)
 Receivers (Photodiodes, APD, CCD)
 Passive Components (Fibres, lenses)
 [Other components (Optocouplers)]
K. Gill
Defects in glasses

defects (‘colour centres’) created by irradiation
 bonds
broken by ionisation/displacement
Ref [8]

K. Gill
defects absorb/scatter incident photons
Colour centres



courtesy D. Doyle (ESTEC) and A.Gusarov (SCK-CEN)
K. Gill
e.g. irradiated
lenses
collimated
beam damage
(different Ce
concentration
affects
darkening)
Fibre types

MM
 short
data links
 good coupling to
VCSEL’s, LED’s
 ATLAS SCT, Larg
 CMS ECAL

Ref [2,10]
SM
 telecoms
 CMS
K. Gill
Tracker
Effect of dopants/impurities in fibres


K. Gill
Avoid phosphorus!
(Note also strong wavelength
dependence)
Ref [29]
Radiation hardening

some fibres become more resistant after high doses

Defects passivated by mobile oxygen atoms
Ref [30]
K. Gill
Optical bleaching


K. Gill
damage dependence on light power in fibre
Modern telecom fibres less sensitive
Ref [31]
Fibre attenuation vs dose

Gamma damage (CMS-TK COTS single-mode fibres)

K. Gill
1310nm
Ref [32]
Fibre attenuation vs fluence


‘Neutron’ damage (CMS TK)
damage actually most likely due to gamma background
Ref [32]
K. Gill
Fibre annealing


damage recovers after irradiation (e.g. gamma)
Damage therefore has dose-rate dependence
Ref [32]
K. Gill
Integrated components
 lenses
• Ball-lenses often
found in fibrecoupled packages
 Glass
covers
• on TO-packages
Ref [10]
K. Gill
Lens darkening
lens
LD
PD
fibre
 Output
efficiency
decreases if lenses
or covers darkened
 (also loss of
response in some
packaged
photodiodes)
Ref [33]
K. Gill
Summary of damage in glass


Main concern is attenuation
many factors affect damage in glass:
 impurities
 wavelength
of light
 production process
 dose rate
 previous irradiation history
 temperature
 light power level
 Should
K. Gill
test samples under application conditions
Components review
 Transmitters
(lasers, LED’s, - total dose, fluence)
 Receivers (Photodiodes, APD, CCD)
 Passive Components (Fibres, lenses)
 Other components (Optocouplers)
K. Gill
Optocouplers

total dose / fluence
SEU

data from COTS used in space applications

 Johnston
K. Gill
et al., NSREC, RADECS
structures

various types
 e.g.
LED + phototransistor
sandwich
lateral
Ref [34]
K. Gill
P+ damage
 LED
output
degradation
 Photoresponse
decrease
 Note:
 low
fluence!
Ref [34]
K. Gill
Gain + photoresponse
 Photoresponse
more important
than decrease in
transistor gain
Ref [34]
K. Gill
Optocoupler SEU


another type
SEU from
protons
measured
 vs
angle
 vs energy
Ref [9]
K. Gill
SEU pulses
 Lid
(+LED) removed
 detector
is most
sensitive element
 64MeV
protons
 many pulses almost
saturate
Ref [9]
K. Gill
X-sect vs angle
 Strong
anglular
dependence
 pronounced
at
lower energies
 direct
ionization
responsible
Ref [9]
K. Gill
SEU X-sect

For protons incident from all directions
Ref [9]
K. Gill
Component sensitivity
Device
Displacement
Total Dose
SEU
Transmitters
LED
LD
Receivers
PD
APD
CCD
Switches
Optocouplers
Optics
Fibres
Connectors
Lens
Danger!!
K. Gill
Beware
Probably OK!
Component effects summary
Device
Displacement
Total Dose
SEU
Non-radiative recombination
Darkening of integrated
components
Transients
Transmitters
LED
LD
Decrease in minority carrier
lifetime
Receivers
PD
APD
CCD
Surface recombination
Generation of electon-hole
pairs
Darkening of integrated
components
Transients
Charge trapping
Flatband voltage shift
Switches
Optocouplers
Non-radiative recombination
Decrease in minority carrier
lifetime in transmitter
Surface recombination
Transients
Darkening of integrated
components
Loss of response in receiver
Optics
Fibres
Connectors
Lens
K. Gill
-
Radiation induced colour
centres
Increased absorption
-
System Issues

Depends on system!
 use
CMS Tracker optical link as example
 system
overview
 COTS validation procedure
K. Gill
e.g. Optical link technology
E.g. CMS Tracker optical links
MT
Tx
MT


lasers
single-mode fibre + array connectors
 Transmitter
 Fibres
MT
and connectors
 Receivers
 plus electronics
Rx
photodiodes
- 1310nm InGaAsP EEL
- SM Ge-doped fibre
- InGaAs p-i-n
Ref [35,36]
K. Gill
CMS Tracker readout and control links
Analogue Readout
50000 links @ 40MS/s
Detector Hybrid
APVamplifiers
Tx Hybrid
MUX
2:1
96

pipelines
128:1 MUX
12
FED
Rx Hybrid
12
PLL Delay DCU
Timing
A
D
C
processing
buffering
DAQ
TTCRx
TTC
Control
CCU
Digital Control
2000 links @40MHz

FEC
6
TTCRx
CCU
8
processing
buffering
CCU
CCU
Front-End
Back-End
Ref [37]
K. Gill
System specs

Analogue readout links
operational
specifications
Number of channels
Rise / fall time
Crosstalk
electrical
specifications
Max. input current
Threshold current
Forward voltage
Reverse voltage
optical
specifications
Wavelength
Max output power
Slope efficiency
Relative non-linearity
RIN
K. Gill
min
typ
1
max
12
2
unit
specification
in/
meas
out
ns
min
min
60
typ
100
10
max
15
1.5
2
min
typ
max
1260
500
1310
1000
.06
1
-130
1360
unit
specification
in/out meas
 Last
2 columns
filled in for each
device type
after testing
mA
mA
V
V
unit
nm
µW
W/A
%
dB/Hz
specification
in/out meas
Ref [35]
LHC Radiation environments: Trackers

K. Gill
(charged hadrons)
(courtesy M. Huhtinen)
LHC Radiation environments: Trackers

K. Gill
(neutrons)
(courtesy M. Huhtinen)
COTS

Recall :COTS not made for LHC environment
 for
applications in radiation environments:
 NO
guarantees of:
• rad-hardness
• reliability

require validation of COTS
 develop
K. Gill
test procedures relevant to application
E.g. COTS lasers for CMS Tracker

1-way InGaAsP EEL on Si-submount with lid
Ref [35]
K. Gill
Validation procedures

e.g. Lasers for analogue links
Highlighted:
Market survey
validation tests
(in-system) lab tests
ageing
g irradiation
p irradiation
n irradiation
annealing
(in-system) lab tests
K. Gill
Radiation test system
Test setup for in-situ measurements

Irradiation
source
Control room
photodetector
signal
Mac + Labview
optical fibre
Datalogger
Unit
Iout
laser
under
test
I generator
current
Vin
MUX + DMM
I/O register
Vout
DAC

K. Gill
set V
Similar for p-i-n and fibre studies
Validation (component rad-damage)
L-I characteristic before/after irradiation

power, P (µW)
1600
pre-irrad
A
B
C
D
post-irrad
A
B
C
D
1200
800
Irradiation:
100kGy 60Co g
1015n/cm2 (0.8MeV)
400
0
0

K. Gill
10
20
30
current, I (mA)
40
50
Increase in laser threshold, decrease in efficiency
Lab testing

In-system test-bed
COMPUTER
GPIB
GPIB
VME
AWG
Pulse GEN.
Tracking GEN.

K. Gill
I2C
ADC
SCOPE
Spectrum ANAL.
measure threshold, gain, noise, linearity, risetime (bandwidth)
Ref [38]
Validation (in-system)

Transfer
characteristics
gain decrease
Increase in d.c.
bias-point


Table 2: I2C pre-bias settings for laser A-E
I2C-bias setting before irradiation
I2C-bias setting after irradiation
K. Gill
A
8
14
B
8
15
Laser
C
9
1A
D
9
19
E
8
8 (not irrad)
Validation (in-system)


Noise
normalized to
peak-signal
Decrease in
signal/noise
 gain
loss
 more noise
at higher
currents
K. Gill
Validation (in-system)


K. Gill
Linearity
not much
change
Validation (in-system)

rise times
Dt
90%
10%
Dt =3.0ns before and after irradiation
(limited by receiver bandwidth)
K. Gill
validation summary

laser validation for CMS TK analogue optical link
 validated
radiation hardness of components
 validated system performance with irradiated
lasers
 potentially
•
•
•
•
K. Gill
sensitive system parameters include:
dynamic range
signal/noise
linearity
bandwidth/settling time
System implications

Allow compensation for damage effects
 threshold
increases
 programmable
d.c. offset bias
 efficiency
loss
 (and variation in optical coupling at connectors)
 variable

gain at transmitter
therefore optimize dynamic range
K. Gill
Summary 1 - recall radiation damage overview
Radiation Environment
Interaction of radiation with material
Ionization
Displacement
SEU
Defect creation
Component
Effects
Effects at system level
K. Gill
Annealing
Summary 2 - recall component effects
Device
Displacement
Total Dose
SEU
Non-radiative recombination
Darkening of integrated
components
Transients
Transmitters
LED
LD
Decrease in minority carrier
lifetime
Receivers
PD
APD
CCD
Surface recombination
Generation of electon-hole
pairs
Darkening of integrated
components
Transients
Charge trapping
Flatband voltage shift
Switches
Optocouplers
Non-radiative recombination
Decrease in minority carrier
lifetime in transmitter
Surface recombination
Transients
Darkening of integrated
components
Loss of response in receiver
Optics
Fibres
Connectors
Lens
K. Gill
-
Radiation induced colour
centres
Increased absorption
-
Conclusions - important issues to consider
What is the radiation environment?
What are the damage effects in components?
What are the implications at the system level?
What are the relevant validation procedures
(attention COTS!)
K. Gill
References - 1
[1] Semiconductor Technology, S.M. Sze, published by Wiley (1985)
[2] RADECS (and NSREC) Technical training courses.
[3] Cluster damage: for example
(a) J.C. Moreno-Marin et al., Nucl. Instr. and Meth. B48, 404-407 (1990)
(b) V.A.J. Van Lint et al., IEEE Trans. Nucl. Sci., 19, 181 (1972)
[4] J.E. Gover and J.R. Srour, Sandia Labs Report SAND85-0776 (1985)
[5] G.C. Messenger, IEEE Trans. Nucl. Sci., 39, No. 3, 468-473 (1992)
[6] Non-ionizing energy loss:
(a) A. Van Ginnekin Fermilab Note FN-522 (1989)
(b) G.P. Summers et al., IEEE Trans. Nucl. Sci., 34, 1134 (1987)
[7] Ionizing Radiation Damage Effects in MOS Devices and Circuits, T. Ma and P. Dressendorfer, published by Wiley
Interscience.
[8] J. Robertson, Phil. Mag. B, 52, No. 3, 371-377 (1985)
[9] A.H. Johnston et al., IEEE Trans. Nucl. Sci. 46, No. 6, 1335-1341 (1999)
[10] Optical Communication Systems (2nd Edition), J. Gowar, Published by Prentice Hall, 1993.
[11] B.H. Rose and C.E. Barne, J. App. Phys., 53(3), 1772-1780 (1982).
[12] A.H. Johnston et al., IEEE Trans. Nucl. Sci. 46, No. 6, 1781-1789 (1999).
[13] J. Beringer et al., ATLAS Internal Note INDET-NO-183 (1997)
[14] Fundamentals of Optical Fiber Communications, W. Van Etten and J. Van der Plaats,
Published by Prentice Hall, 1991.
[15] Seminconductor Lasers (2nd Edition), G.P. Agrawal and N.K. Dutta, published by Van
Nostrand Reinhold, 1993.
[16] K. Gill et al., Proceedings of 4th Workshop on Electronics for LHC Experiments, London, 1998.
[17] K. Gill et al., Proceedings of SPIE 3440, 89-99 (1998)
[18] K. Gill et al., submitted to Conference on Photonics for Space, SPIE Annual Meeting 2000.
K. Gill
References - 2
[19] K. Gill et al., Proceedings of 1999 RADECS conference, Fontevraud, 1999.
[20] K. Gill et al., Internal Report.
[21] D.G. Charlton et al., Nucl. Instr. And Meth. A443, 430-446 (2000)
[22] ATLAS SCT VCSEL annealing and ageing tests:
http://www.atlas.uni-wuppertal.de/optolink/wuppertal/annealing.html
[23] ATLAS SCT photodiode ageing tests:
http://www.ep.ph.bham.ac.uk/user/mahout/irradn/sctmeeting/jun99/
[24] V. Radeka, Nucl. Instr. and Meth. A226209-218 (1984)
[25] G.R. Hopkinson, IEEE Trans. Nucl. Sci. 46, No. 6, 1790-1796 (1999).
[26] K. Deiters et al., Nucl. Instr. and Meth. A442 193-197 (2000)
[27] P. Marshall et al., IEEE Trans. Nucl. Sci., 43, No. 2, 645-653 (1996)
[28] F. Faccio et al, submitted to RADECS Workshop, 2000
[29] E.J. Friebele et al., App. Opt. 19, No. 17, 2910-2916 (1980)
[30] D. Griscom, J. App. Phys., 77 (10) 5008-5013 (1995)
[31] B.D. Evans, Proc. SPIE 1174, 20-26 (1989)
[32] J. Troska, Proc. SPIE 3440, 112-119 (1998)
[33] P. Marshall et al., IEEE Trans. Nucl. Sci., 39, No. 6, 1982-1989 (1992)
[34] A.H. Johnston et al., IEEE Trans. Nucl. Sci. 43, No. 6, 3167-3173 (1996).
[35] CMS Tracker Optical Links www site:
http://cern.web.cern.ch/CERN/Divisions/ECP/CME/OpticalLinks/
[36] F. Vasey et al, IEEE Trans. Nucl. Sci., 45, No. 3, 331-337, (1998)
[37] CMS Tracker Technical Design Report., CERN LHCC 98-6, (1998)
[38] F. Jensen et al, CMS Technical Note, CMS Note 99-074 (1999)
K. Gill