measurements on single and poly crystal diamond samples at cern
DESCRIPTION
Measurements on single and poly crystal diamond samples at CERN. Luis Fernandez-Hernando Christoph Ilgner Alick Macpherson Alexander Oh Terry Pritchard Eleni Berdermann Peter Weilhammer. Diamond Characterization. Measurements performed on diamonds: I-V curve. - PowerPoint PPT PresentationTRANSCRIPT
Measurements on single and poly crystal diamond samples
at CERN
Luis Fernandez-HernandoChristoph Ilgner
Alick MacphersonAlexander OhTerry Pritchard
Eleni BerdermannPeter Weilhammer
Diamond Characterization
Measurements performed on diamonds:• I-V curve.
First quality check of the samples, metallisations.
• Collection distance vs time. Study of the pumping.
Charge collection distance at 1 V/ µm.
• Collection distance vs bias voltage. Measurement of the charge collection distance at different electric fields.
Study of the radiation damage.
Study of the polarization.
• I-T curve. Find the thermo-stimulated current peak. Number of traps.
Depumping of diamonds.
Diamond Characterization
The software gets the top value of the peak and deducts the average value of the base
Those values are averaged over a certain time (usually 5 min) for calculating the collection distance
-1.5
-1
-0.5
0
0.5
1
1.5
-1200 -1000 -800 -600 -400 -200 0 200 400 600 800 1000 1200
Bias [V]
Cu
rren
t [n
A]
0 to 1000 V
0 to -1000 V
-7-6-5-4-3-2-1012
-1000 -800 -600 -400 -200 0 200 400 600 800 1000
Bias [V]
Cu
rren
t [n
A]
0 to 900
0 to -900
I-V curves
CDS116
500 μm thick polycrystalline diamond
CDS126
300 μm thick polycrystalline diamond
Polycrystalline diamond I-V curves:
I-V curves
-200
-150
-100
-50
0
50
100
150
200
250
300
-300 -200 -100 0 100 200 300
Bias [V]
Cu
rren
t [n
A]
0 to 240 V
230 to 0
0 to -240
-230 to 00.001
0.01
0.1
1
10
100
1000
0 50 100 150 200 250 300
Bias [V]
Cu
rren
t [n
A]
0 to 240 V
230 to 0
-4000
-3500
-3000
-2500
-2000
-1500
-1000
-500
0
500
-500 -400 -300 -200 -100 0 100 200 300 400 500
Bias [V]
Cur
rent
[nA
]
0 to 400 V
0 to -400 V
0.001
0.01
0.1
1
10
100
1000
10000
0 50 100 150 200 250 300 350 400 450
Bias [V]
Cur
rent
[nA
]
0 to 400 V
0 to -400 V
Mono-crystalline diamond I-V curves:
E6-sc-01
440 μm thick monocrystalline diamond
CDS134
490 μm thick monocrystalline diamond
0
50
100
150
200
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Dose [Gy]
Co
llect
ion
dis
tan
ce [
um
]
0
50
100
150
200
250
0 1 2 3 4 5
Dose [Gy]C
olle
ctio
n d
ista
nce
[u
m]
Pumping
Pumping for an 360 μm thick polycrystalline CVD diamond at 1V/ μm.
Pumping for a 500 thick polycrystalline CVD diamond at 1V/ μm.
Pumping performed with a collimated 90Sr β-source.
e6-SC-01
0
100
200
300
400
500
600
0 0.5 1 1.5 2 2.5
Time [h]
C.C
.D.
[um
]; T
emp
. [C
]
0.01
0.10
1.00
Cu
rren
t [n
A]
Before heating. C.D. [um]
After heating. C.D. [um]
Before heating. Temp. [C]
Aftrer heating. Temp. [C]
Before heating. Current [nA]
After heating. Current [nA]
Pumping
Monocrystal diamond e6-sc-01 does not present pumping.
The collection distance was bigger than the thickness.
After a heating process that collection distance went to a more reasonable value.
CDS113
0
50
100
150
200
250
0 10 20 30 40 50 60
Time [h]
Co
llec
tio
n d
ista
nce
[u
m]
100 V
200 V
300 V
400 V
500 V
600 V
700 V
600 V
500 V
400 V
300 V
200 V
100 V
Collection distance vs Bias
Signal from CDS113 (500 µm). to a MIP vs time at different voltage steps. A polarization is present in each step.
-250
-200
-150
-100
-50
0
50
100
150
200
250
300
-2 -1.5 -1 -0.5 0 0.5 1 1.5 2
E [V/um]
Co
llec
tio
n d
ista
nce
[u
m]
0 to 700 V
700 to 0 V
0 to -700 V
-700 to -100 V
Collection distance vs Bias
Collection distance vs the electric field for CDS113 (500 µm). Each point represents the signal after a stabilization period of 4 hours.
-400
-300
-200
-100
0
100
200
300
400
-250 -200 -150 -100 -50 0 50 100 150 200 250
Bias [V]
CC
D [u
m]
0 to 200 (a)
200 to 0 (a)
0 to -200 (b)
-200 to -20 (b)
-600
-400
-200
0
200
400
600
-0.40 -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40
E [V/um]
Co
llect
ion
dis
tan
ce [u
m]
0 to 150 V
150 to 0
0 to -150
-150 to 0
Collection distance vs Bias
Collection distance vs Electric field for e6-sc-01 (440 µm).
Collection distance vs Bias CDS134 (490 µm).
CDS134 polarity a
0
50
100
150
200
250
300
350
400
450
0 5 10 15 20
Time [h]
CC
D [
um
]
0 V
20 V
40 V
60 V
80 V
100 V
120 V
140 V
160 V
180 V
200 V
Collection distance vs Bias
CDS134, monocrystal diamond, presented polarization periods like any polycrystal. E6-sc-01 did not show polarization.
-250
-200
-150
-100
-50
0
50
100
150
200
250
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5
E [V/um]
Co
llect
ion
dis
tan
ce [
um
]
after 1st irrad
after 2nd irrad
Before irradiation
-250
-200
-150
-100
-50
0
50
100
150
200
250
-2 -2 -1 -1 0 1 1 2 2
E [V/um]
Co
llect
ion
dis
tan
ce [
um
]
after 1st irrad
after 2nd irrad
Before irrad
CDS116 (500 µm).
First irradiation of 1015 protons/cm2.
Second irradiation of 2.8x1015 protons/cm2. Equivalent to 10 years of LHC at normal operation near the IP5.
Radiation damage on polycrystalline samples
CDS126 (300 µm).
First irradiation of 5x1014 protons/cm2.
Second irradiation of 2.3x1015 protons/cm2.
-50
-30
-10
10
30
50
70
90
110
130
150
0 5 10 15 20 25 30 35 40 45
Time [h]
Co
llec
tio
n d
ista
nce
[u
m]
100 V bias
200 V bias
300 V bias
400 V bias
500 V bias
400 V bias
300 V bias
200 V bias
100 V bias
0 V bias
Radiation damage
The radiation affected the signal of the diamond and the evolution of the polarization and depolarization. The plot is of CDS126.
0
50
100
150
200
250
0 0.25 0.5 0.75 1 1.25 1.5 1.75
Time [h]
Co
llect
ion
dis
tan
ce [
um
]
0.01
0.1
1
10
100
Cu
rren
t [n
A]
Collection distance CDS116 at 500 V
Current CDS116
0
50
100
150
200
0 1 2 3 4 5 6 7Time [h]
Co
llec
tio
n d
ista
nc
e [
um
]
0.01
0.1
1
10
100
Cu
rre
nt
[nA
]
Collection distance CDS126 at 300 V
Current CDS126
Radiation damage
CDS 116 signal at 1 V/µm and leakage current after the first irradiation.
CDS 126 signal at 1 V/µm and leakage current after the first irradiation.
Radiation damage
0
50
100
150
200
250
0 1 2 3 4 5 6Dose [Gy]
Co
lle
cti
on
dis
tan
ce
[u
m]
0.01
0.1
1
10
Cu
rre
nt
[nA
]
Collection distance CDS116,500 V
Current CDS116
0
20
40
60
80
100
120
140
160
0 1 2 3 4
Dose [Gy]
Co
llec
tio
n d
ista
nc
e [
um
]
0.01
0.1
1
10
Cu
rre
nt
[nA
]
Collection distance CDS126,300 V
Current [nA]
CDS 116 signal at 1 V/µm and leakage current after the first irradiation and after a heating process that fully depumped the diamond. The dose necessary for pumping it has increased.
CDS 126 signal at 1 V/µm and leakage current after the first irradiation and after a heating process that fully depumped the diamond.
Radiation damage
0
20
40
60
80
100
120
140
160
0 25 50 75 100
Time [h]
Colle
ctio
n di
stan
ce [u
m]
0.001
0.01
0.1
1
Curr
ent [
nA]
Collection distance CDS116, 500 V
Current CDS116
0
20
40
60
80
100
120
140
0 25 50 75 100 125 150
Time [h]
Co
lllec
tio
n d
ista
nce
[u
m]
0.001
0.01
0.1
1
Cu
rren
t [n
A]
Collection distance CDS126, 300 V
Current CDS126
CDS 116 signal at 1 V/µm and leakage current after the second irradiation.
CDS 126 signal at 1 V/µm and leakage current after the second irradiation.
Diamond showed a signal degradation due to radiation damage of a 42% after a proton fluence equivalent to 10 years of normal operation of the LHC near the IP5.
The leakage current from the diamonds decreased down to a 60% from its original value prior to irradiations.
The most important effect of radiation damage on diamond is the creation of charge traps in its bulk. Due to this effect pumping periods increase considerably. The number of generated traps can be so important that in case the diamond is depumped those traps will suck the electron hole pairs generated by a passing particle masking the signal completely.
After performing a TSC diamonds showed, after a pumping period, to have recovered the original collection distance values. New traps have been created, but those once filled do not interfere with the signal. Damage that made a decrease on the signal seemed to have disappeared.
Some conclusions
0
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300
0 50 100 150 200 250 300 350
Temperature [C]
Cu
rren
t [n
A]
0
50
100
150
200
250
300
350
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Time [min]
Tem
per
atu
re [
C]
TSC measurements
Temperature vs time for the measurements. The rate is quite constant and reproducible.
Current vs temperature for CDS126 after the first irradiation with the proton beam.
0
10
20
30
40
50
60
70
80
90
0 50 100 150 200 250 300 350 400
Temperature [C]
Cu
rren
t [n
A]
heating up
cooling down
-1
0
1
2
3
4
5
6
7
8
9
0 50 100 150 200 250 300 350
Temperature [C]
Cu
rre
nt
[nA
]
heating up
cooling down
TSC measurements
Current vs temperature for e6-sc-01 after 2 hours of irradiation with the strontium source.
Current vs temperature for CDS115 after 2 hours of irradiation with the strontium source.
The similar temperatures at where the TSC peaks were produced, indicate that the charge traps in those diamonds are in similar energy levels.
That could indicate that the kind of impurities is the same for all of them. The two polycrystalline diamonds measured were made from the same wafer, therefore this is expected.
The monocrystal e6-sc-01, instead, did not show any hint about charge traps during the collection distance measurements, it did not pump neither polarized, yet a TSC peak is observed, also in a similar temperature range. That confirms the presence of traps, from impurities, in the crystal lattice.
Impurities that may be similar to the polycrystalline ones. Nevertheless, the level of current achieved by the monocrystal is much less important than the ones achieved from the polycrystalline ones.
Some conclusions