DETECTOR TESTING FACILITY AT RBI
(IBIC (Ion Beam Induced Charge) EXPERIMENT)
Veljko Grilj
Ruđer Bošković Institute, Zagreb, Croatia
Silicon Detector Workshop
Split, Croatia, 8-10 October 2012
1. ACCELERATORS
1.0 MV HVE
Tandetron accelerator
6.0 MV EN Tandem Van
de Graaff accelerator
PIXE/RBS
1
2
In-air PIXE
Dual-beam
irradiation
IAEA beam
line
TOF ERDA
Det.
test.
Ion
microprobe
IBIC
PIXE crystal
spectrometer
Nuclear
reactions
1.1. New detector testing beam line
1. Beam deflector and/or
scanner
2. Pre-chamber with beam
degrader/diffuser
3. Final chamber with
beam in air capability
1.2. Nuclear microprobe
 ION POSITION
- focusing and scanning
q u a d ru p o le d o u b le t
fo c u s in g le n s
s a m p le
p ro to n
beam
o b je c t s lits
 IONS
Y
- p, , Li, C, O,..
X
scan
g e n e ra to r
Y
16
O
12
C
IB IC
s ig n a l
7
X
Li
a lp h a s
IB IC - c h a rg e
c o lle c tio n e ffic ie n c y
 RANGE
 ION RATE
- 2 to 200 m
- currents 0 - 106 p/s
im a g e s
p ro to n s
1.3. Available ion beams
127I
100000
Number of charge pairs (ion*nm)
-1
10000
1000
C
Si
12C
He
Accel. voltages 0.1 to 6.0 MV
Negative Ion sources:
- Duoplasmatron
- RF He
- Sputtering
Cu I
100
10
28Si
protons
1
0,1
0,01
Eions = 1 MeV/amu
MIPs
proton
1E-3
1E-4
1E-5
1E-6
500
Depth (nm)
1000
Silicon
I 127
Si 28
C 12
He 4
H1
Range(µm)
E=1 MeV
0.37
1.13
1.6
3.5
16.3
4.8
9.5
69.7
709
Range (µm) 3.7
E=10 MeV
2. ION BEAM INDUCED CHARGE - theory
Principles of radiation detection techniques
Vout
Q
Deposited energy
Free charge genetration
and transport
V
Ouput signal Vout
Vout = F (deposited energy, free carrier transport)
Nuclear spectroscopy
Well known
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
Vout
Q
Deposited energy
Free charge genetration
and transport
V
Ouput signal Vout
Vout = F (deposited energy, free carrier transport)
Well known
Material characterization
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
b) Creation of e-h pairs
a) Energy deposition by ions
+
+
+
-
+ - +
+ +
- -
800
E n e rg y lo ss (ke V / m )
+
-
700
2 M e V  -p a rticle s
600
500
400
300
2 M e V p ro to n s
200
100
0
0
5
10
15
20
25
D e p th ( m )
Bethe formula:

dE
dx
4 e z
4

m0v
2
2
2
2
 2m0v 2

v  v 
NZ  ln
 ln  1  2   2 
I
c  c 


N e/h 
E dep
 eh

MeV
eV
 10
6
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
year 1964
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=0
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
V
0 .0 7 5
I
0 .0 5 0
v
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=1
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=2
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=3
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=4
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=5
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=6
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=7
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=8
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=9
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=10
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
I( t )  q 
0 .0 2 5
v
d
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
c) Free charge carrier transport → charge induced at electodes
 
  E ( r ( t ))
Gunn’s theorem: ii   q v
Vi
Vout
T=11
V j  const .
1 .0
Q
0 .8
Q
0 .6
0 .4
0 .2
0 .0
d
0 .0 7 5
0 .0 5 0
I
V
0 .0 2 5
0 .0 0 0
-2
0
2
4
6
8
T im e
10
12
14
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
Impact of defects on charge carriers mobility:
  
1 .0
1 .0
0 .8
0 .8
0 .6
0 .6
Q tot  q
0 .4
Q
Q
 
0 .4
0 .2
0 .2
0 .0
0 .0
0 .0 7 5
I  q
0 .0 7 5
d
0 .0 5 0
I
v
I
0 .0 5 0
Q tot  q
0 .0 2 5
0 .0 2 5
0 .0 0 0
0 .0 0 0
-2
0
2
4
6
8
10
12
-2
14
T im e
- physical opservable: CCE 
0
2
4
6
8
10
12
14
16
T im e
Q induced
Q created
I  q
 t
 exp   
d
 
v
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
- direct implication from Gunn’s theorem:
 
  E ( r ( t ))
ii   q v
Vi
- consequences:
a)
ion beam
V j  const .
CCE
holes
Q induced
 
 q
 Vi


final

Vi
start




100%
electrons
b)
- V0
- V0
he
2. ION BEAM INDUCED CHARGE - theory
Principles of IBIC
Advantages of using focused ions:
- spatial resolution
- wide spread of ion ranges
2 m
4 m
2 MeV H+ in Si
Electrons
40 keV
3 MeV H+ in Si
6 m
20 m
20 m
147 m
90 m
47 m
4 MeV H+ in Si
Electrons
10 keV
2. ION BEAM INDUCED CHARGE
Samples
PIN
diode
2. ION BEAM INDUCED CHARGE
Samples
Si DSSD
(16x16 strips)
Ion beam
CdInGaSe
solar cell
CVD
diamond
2. ION BEAM INDUCED CHARGE
Geometries
100 m
Si Schotky diode
3. IBIC EXAMPLES
Frontal IBIC
4.5 MeV Li
range 6μm
127I
28Si
12C
He
surface
3 MeV protons
range 90 μm
- by proper selection of ion type
and energy, CCE (charge
collection efficiency) at different
sample depths can be imaged.
proton
bulk
Si Schotky diode
3. IBIC EXAMPLES
Frontal IBIC – depth profiling
4.5 MeV Li7 ions
(range in Si 8.5 m)
7.875 O16 ions
(range in Si 4.5 m)
4 .5  m

0
4 .5  m

0
 dE

dx 

 dx
 O  ions
 dE

dx 

 dx
 Li  ions
Li image - O image / 2.8
IBIC between 4.5 and 8.5 m
 2 .8
4H-SiC diode
3. IBIC EXAMPLES
Frontal IBIC – drift & diffusion
drift
Q  Q depletion  Q neutral
E≠0
 W  dE 

  

dx


 0  dx 

E=0
diffusion
 d  dE 
 
  exp
 W  dx 
 x W


Lp



  dx 



minority carrier
diffusion length
4H-SiC diode
3. IBIC EXAMPLES
Frontal IBIC – drift & diffusion
drift
  dE 

  
  dx  
dx

0

W
Q  Q depletion  Q neutral
E≠0
E=0
diffusion
  dE 
 
  exp
dx

 W 
d
 x W


Lp



  dx 



4H-SiC diode
3. IBIC EXAMPLES
Frontal IBIC – drift & diffusion
drift
Q  Q depletion  Q neutral
 W  dE 

  
  dx  
dx

0

E≠0
E=0
diffusion
 d  dE 
 
  exp
dx

 W 
 x W


Lp



  dx 



4H-SiC diode
3. IBIC EXAMPLES
Frontal IBIC – drift & diffusion
drift
Q  Q depletion  Q neutral
 W  dE 

  
  dx  
dx

0

diffusion
 d  dE 
 
  exp
dx

 W 
 x W


Lp



  dx 



- direct measurement of diffusion length
E≠0
Lp = (9.0±0.3) μm
CdZnTe
3. IBIC EXAMPLES
- sample thickness > 2 mm
- IBIC with 2 MeV p+, range < 30 μm
Frontal IBIC – μτ mapping
- from Gunn’s theorem with assumptions of full depletion,
constant electric field and generation near one electrode:
Hecht equation
CCE 
  h / e  E
d

 1  exp


d

     E
h/e

holes
electrons
  e , av



 
 1  10
3
2
cm / V
  h , av
 4  10
5
2
cm / V
M. Veale et al., IEEE TNS, 2008
Si power diode
3. IBIC EXAMPLES
Lateral IBIC – drift and diffusion
ion beam
pn junction
E<0
E=0
z
zd
0
1
0 ,8
C o lle ctio n e fficie n cy
0 ,6
CCE (z<zd) ≈ 1
28 V
6 0 .4 V
0 ,4
L p = ( 2 7 .3 ± 0 .8 )  m
 = (0 .5 7 ± 0 .0 3 )  s
0 ,2
CCE (z>zd) = exp(-(z-zd)/Lp,n)
9 0 .6 V
1 1 7 .5 V
0 ,1
0 ,0 8
50
100
150
D e p th (  m )
200
250
hole or electron
diffusion length
CdZnTe
3. IBIC EXAMPLES
Temperature dependent lateral IBIC
3 MeV proton beam
- temperature range 166-329 K
Bias
Preamplifier
Amplifier
X-Y scanning
ADC
Au-contacts
CdZnTe
Cooling-heating
DSO
Digital oscilloscope
TRIBIC
DAQ
IBIC
MAPS
CdZnTe
3. IBIC EXAMPLES
Temperature dependent lateral IBIC
IBIC line scan (anode to cathode)
for CCE=100%
1 .0
329 K
0 .9
()e=(1.4)*10-3 cm2/V
()h=1*10-5 cm2/V
322 K
296 K
0 .8
287 K
0 .7
256 K
238 K
CCE
0 .6
211 K
177 K
0 .5
0 .4
0 .3
0 .2
0 .1
0 .0
0
25
50
75
100
125
150
175
200
d is ta n c e fro m a n o d e (c h a n n e ls )
225
250
275
3. IBIC EXAMPLES
Radiation hardness tests
Ion beam induced damage:
IBIC on-line monitoring:
6 Li7 m-2 = 6×108 cm-2
(4 events per pixel)
50 Li7 m-2 = 5×109 cm-2
- For 100% ion impact detection efficiency, IBIC
can be used to monitor irradiation fluence
- Irradiation of arbitrary shapes
- On-line monitoring of CCE degradation
3. IBIC EXAMPLES
Radiation hardness tests
Irradiation pattern (3 x3 quadrants,
50 x 50 pixels, 100 x 100 m2 each,
20 m gaps, tirrad = 5 min. – 3 h )
- damage done with He, Li, O & Cl ions of similar range
Si diode
Si diode
3. IBIC EXAMPLES
Radiation hardness tests
Modeling of CCE:
- doping profiles & el. field (CV)
- drift velocity profiles (el. field)
- hole contribution negligible
- vacancy profile (SRIM)
- predominantly divacancies (DLTS)
- dE/dx from (SRIM)
- electron lifetime:
CCE  1  K
*
e ,h

k e ,h   e ,h
*
e ,h
effective
fluence
k  = 0.88 *10-15
k = 0.18 !!
18% of radiation induced defects
leads to stable divacancies !
4. ION INDUCED DLTS
Radiation produces lattice defects
el. active traps, CCE<100%
Question: how to calculate the energy levels of produced traps?
Answer: DLTS, but what if.....a) number of traps is very very large?
b) I want good spatial resolution?
c) my sample is diamod?
4. ION INDUCED DLTS
Radiation produces lattice defects
el. active traps, CCE<100%
Question: how to calculate the energy levels of produced traps?
Answer: DLTS, but what if.....a) number of traps is very very large?
b) I want good spatial resolution?
c) my sample is diamod?
Steps:
- IBIC with MeV ions, charge carriers will fill traps
- record cumulative collected charge in time using charge sensitive preamp
and digital scope at different temperatures
- choose rate windows like in conventional DLTS
- plot Q(t2)-Q(t1) vs. T
- make Arrhenius analysis and get activation energy of the defect
4. ION INDUCED DLTS
- irradiation with 1 MeV electrons,   1  10 15 cm  2
6H-SiC diode
N. Iwamoto et al., IEEE TNS, 2011
el. active traps, CCE<100%
- IBIC with 5.486 MeV alphas
cumulative collected charge
250K<T<320 K
Estimated activation energy:
Q(t2)-Q(t1) vs. T
IIDLTS
0.50±0.05 eV
DLTS
0.53±0.07 eV
400 μm thick
natural diamond
5. TIME RESOLVED IBIC - TRIBIC
(transient current technique, TCT)
- use of current sensitive amplifier instead of charge sensitive
- high frequency oscilloscope,
- novel technique ???


 15 ns
 t
I  q   exp   
d
 
v
C. Canali, E. Gatti, S.F. Koslov, P.F. Manfredi,
C. Manfredotti, F. Nava, A. Quirini
Nucl. Instr. Meth. 160 (1979) 73-77
5. TIME RESOLVED IBIC - TRIBIC
TCT on scCVD diamond at low temperatures
H. Jansen (CERN), CARAT Workshop,
GSI, 2011
- 2 GHz, 40 dB, 200ps rise time amplifier (CIVIDEC)
- broad-band 3GHz scope (LeCroy)
5. TIME RESOLVED IBIC - TRIBIC
Saturation velocity
H. Jansen (CERN), CARAT Workshop,
GSI, 2011
Lower fields are required to
reach saturation velocity at low
tempertures
5. TIME RESOLVED IBIC - TRIBIC
Plasma effects
Plasma effects
5. TIME RESOLVED IBIC - TRIBIC
Charge trapping/detrapping
H. Jansen (CERN), CARAT Workshop,
GSI, 2011
Significantely higher charge
trapping at low temperatures !!
5. TIME RESOLVED IBIC - TRIBIC
Charge trapping/detrapping
H. Jansen (CERN), CARAT Workshop,
GSI, 2011
Detrapping (~ 10 ns)
5. TIME RESOLVED IBIC - TRIBIC
500 μm thick
scCVD diamond
Position sensitivity
- scCVD diamond, 500 μm thick
- lateral scan with 4.5 MEV p
- (μτ)e< (μτ)h
- 6 GHz, 15dB preamp (Minicircuits)
- 5 GHz, 10 GS/s scope (LeCroy)
Achievable resolution ≈ 10 μm
0
500μm