Thesis Presentation

Academic year 2013-‘14
UNIVERSITY OF TURIN
Materials Science Master Degree
Production and characterisation of diamond’s
nanocrystals with luminescent singel centres
Supervisor:
Dr. Paolo Olivero
Candidate:
Alessandro Marsura
Examiner:
Dr. Marco Truccato

Thesis outline
Theoretical aspects:
• Single photon sources
• Diamond
Production’s optimisation:
• Pre-radiation chemical treatments
• Ionic radiation and annealing
• Post-annealing chemical treatments
Opto-physics characterisation:
• Sample’s mapping
• Photoluminescence spectra
• HBT interferometry
Conclusions and prospects:
• Production’s optimisation
• Opto-physics characterisation

Sviluppo del lavoro di tesi
• Diamond
• Post-annealing chemical treatment
Thesis outline

Single photon sources
What are they?
Devices capable of emitting a single photon in
response to an excitation signal
Applications?
Quantum computing, quantum communication
and criptography, metrology.
3
I.Aharonovich et al., Rep.Prog.Phys.74,076501, 2011.
Technological state of the art:
A. Strongly attenuated pulsed laser
• “on demand” ✓
• multi-photonic components ✗
B. Parametric down conversion (PDC)
• “heralded” photons ✓
• non deterministic technique ✗
C. Quantum dots in semiconductors
• only mono-photonics components ✓
• cryogenic work’s temperature ✗
D. Luminescent centres in solids
• isolated quantum systems, manipulable at room temperature ✓
• “on demand”, only mono-photonics components ✓

What are they?
Applications?
3

What are they?
3
Applications?

3
What are they?
Applications?

Chemical composition:
Allotrope of carbon sp3 hybridised
Crystallographic characteristics:
• F.c.c. unit cell
• Lattice bases (0,0,0) (1/4,1/4,1/4)
• Lattice constant equal to 3.57Å
• Atomic density 1.77×1023 cm-3
Opto-electronics properties:
• Energy Gap equal to 5.5 eV
• Insulating material
• Transparent form FIR to NUV
4
Diamond

What are they?
Defects of the crystal lattice (vacancies, sostituzional-interstitial atoms)
• energetic levels in the band gap
• radiative transitions when exited
5
I.Aharonovich et al., Rep.Prog.Phys.74,076501, 2011.
Luminescent centres in diamond
Diamond

Thesis outline
• Diamond
• Post-annealing chemical treatment

Pre-radiation chemical treatments
batch model diameter (nm)
nitrogen’s concentration
(ppm)
diamond type
d_p_06 micron + mda 0-.25 0-250 100 Ib
batch reagent used
temperature
(°C)
temporal duration
(h)
treatments name
d_p_06
HNO3 100 48 “A"
H2SO4/HNO3 (9:1) 75 72 “B"
Original sample
Chemical treatments
6

(ppm)
diamond type
d_p_06 micron + mda 0-.25 0-250 100 Ib
batch reagent used
temperature
(°C)
temporal duration
(h)
treatments name
d_p_06
HNO3 100 48 “A"
H2SO4/HNO3 (9:1) 75 72 “B"
Original sample
Chemical treatments
6
vibrational modes of “sp3” carbon

(ppm)
diamond type
d_p_06 micron + mda 0-.25 0-250 100 Ib
batch reagent used
temperature
(°C)
temporal duration
(h)
treatments name
d_p_06
HNO3 100 48 “A"
H2SO4/HNO3 (9:1) 75 72 “B"
Original sample
Chemical treatments
6
symmetric stretching -SO3
−
asymmetric stretching -SO3
−

Ionic radiation and annealing
ionic
species
ionic energy
(MeV)
beam
dimensions
(mm2)
ionic courent
(nA)
radiation time
(s)
resulting ﬂuence
(cm-2)
corresponding
samples
protons 2
7×3 86 574 5 x 1013
1_A 1_B
7×3 186 585 1 x 1014
2_A 2_B
7×3 186 1158 2 x 1014
3_A 3_B
7×3 397 1207 5 x 1014
4_A 4_B
Ionic radiation
Annealing
pressure
(mBar)
treatment’s phase
initial
temperature (°C)
ﬁnal
temperature (°C)
temporal
duration
(min)
gradient
(°C min-1)
800
(di N2)
heating 50 800 75 +10
plateau 800 800 60 ///////////////////////////
cooling 800 50 75 -10
ρV=λV×F
7

Ionic radiation and annealing
ionic
species
ionic energy
(MeV)
beam
dimensions
(mm2)
ionic courent
(nA)
radiation time
(s)
resulting ﬂuence
(cm-2)
corresponding
samples
protons 2
7×3 86 574 5 x 1013 1_A 1_B
7×3 186 585 1 x 1014 2_A 2_B
7×3 186 1158 2 x 1014 3_A 3_B
7×3 397 1207 5 x 1014 4_A 4_B
Ionic radiation
Annealing
pressure
(mBar)
treatment’s phase
initial
temperature (°C)
ﬁnal
temperature (°C)
temporal
duration
(min)
gradient
(°C min-1)
800
(di N2)
heating 50 800 75 +10
plateau 800 800 60 ///////////////////////////
cooling 800 50 75 -10
7

Post-annealing chemical treatment
treated samples treatment’s phase
quantity
(parts)
temporal
duration
(min)
3_A, 1_A, 1_B
attacco con H2SO4 3 30
aggiunta di H2O2 1 20
rinsing in “piranha”
solution
8
2−

Post-annealing chemical treatment
8
treated samples treatment’s phase
quantity
(parts)
temporal
duration
(min)
3_A, 1_A, 1_B
attacco con H2SO4 3 30
aggiunta di H2O2 1 20
rinsing in “piranha”
solution
symmetric stretching -SO3
−
−
2−

Sample’s mapping
9
Confocal microscope
Features:
• Pinholes ensure the acquisition of the radiation belonging to the only
desired focal plane
• Theoretical spatial resolution is equal to the diffraction limit of light
• Surface mapping point by point
• Optical localisation of the single centres of luminescence

Sample’s mapping
Instrumental apparatus
2
3
5 5
6
7
8 9
10
11
12
13
13
10
(2)
(6)
(4)
(5)(5)
(3)
(10)
(7)(8)
(9)
Optical chain
(1)
4
Additional components:
11. Spectrometer-monochromator
12. Beam-splitter
13. Single photon detector
Technical data of pulsed laser:
emission
wave-
lenght
(nm)
maximum
repetition
frequency
(MHz)
temporal
duration of
single pulse (ps)
instantaneous
power per single
pulse (mW)
532 80 <100 20

1
2
3
4 4
5
6
7 8
9
10
11
12
12
3_A sample
11
Area#1 Area#2
Parameters:
• Laser’s repetition frequency equal to 80 MHz
• (80×80) μm2, (320×320) pixel
• Dwell time 10 ms
Parameters:
• (80×80) μm2, (533×533) pixel
[F=2×1014 cm-2]
Sample’s mapping

1_A sample
12
Parameters:
• (80×80) μm2, (400×400) pixel
• Dwell time 5 ms
[F=5×1013 cm-2]
Sample’s mapping

12
20×
1_A#1 centre
Parameters:
• (5×5) μm2, (70×70) pixel
Sample’s mapping
1_A sample

1_A sample
12
1_A#2 centre
7×
Parameters:
• (10×10) μm2, (144×144) pixel
• Dwell time 5 ms
Sample’s mapping

1_B sample
13
Parameters:
• (80×80) μm2, (1600×1600) pixel
• Dwell time 5 ms
[F=5×1013 cm-2]
Sample’s mapping

20×
1_B#1 centre1_B sample
13
Parameters:
• (5×5) μm2, (90×90) pixel
Sample’s mapping

Photoluminescence spectra
600 650 700 750
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
Fotoluminescenza[a.u.]
Lunghezza d'onda [nm]
Spettro di emissione del campione 3A - area 1
Spettro di emissione del campione 3A - area 2
Area#1
Area#2
14
ZPL NV−
(638 nm)
3_A sample [F=2×1014 cm-2]
Aggregate’s spectra

Area#1
Area#2
14
Y. Dumegie, et al., Journal of Luminescence, 109, 61-67, 2004.
Bibliographical reference
3_A sample [F=2×1014 cm-2]

15
Centro1_A#1
Centro1_A#2
1_A & 1_B samples [F=5×1013 cm-2]
Centro1_B#1
Single nano-crystal’s spectra

HBT interferometry
16
Features:
• Determination of statistics characterising coincident events
• Discrimination of the luminescent cetre’s nature
source’s type value of g(2)(0) comment
classical
source
g(2)(0) ≥ 1
g(2)(0) ≥ g(2)(τ)
g(2)(0) = 1 ⇔ I(t)=cost.
coherent
source
g(2)(0) = 1 ⩝ t
quantum
source
g(2)(0) < 1
g(2)(0) < 0.5 ⇒
single photon source
g 2( )
t( )=
I t( )⋅ I t +τ( )
I t( )
2
classical
coherent
quantum
Delay times [ns]
g(2)(t)
Hambury Brown & Twiss interferometer

17
Components:
• Beam Splitter;
• 2 start & stop single photon detector (operating in “Geiger mode”);
• Time to Amplitude Converter (TAC);
• Multi Channel Analyzer (MCA);
• Counter.
Instrumental apparatus
HBT interferometry

18
1_A#1 centre
gsperimentale
2( )
t = 0( )=
A t = 0( )
A t ≠ 0( )
gcorretta
2( )
t = 0( )=
gsperimentale
2( )
t = 0( )+ ρ2
−1
ρ2
S = Ri = 102 kcps
B = 20 kcps
= 0.73± 0.02
R1 = R2 = 102 kcps
T = 1000 s
tr = 25 ns
C * t( )=
C t( )
R1R2T tr
ρ =
S
S + B
I = S + B
backﬂash’s peak
coincident events’s “dip”
HBT interferometry
Interferometry’s results:

18
gsperimentale
2( )
t = 0( )=
A t = 0( )
A t ≠ 0( )
gcorretta
2( )
t = 0( )=
gsperimentale
2( )
t = 0( )+ ρ2
−1
ρ2
S = Ri = 102 kcps
B = 20 kcps
= 0.73± 0.02
R1 = R2 = 102 kcps
T = 1000 s
tr = 25 ns
C * t( )=
C t( )
R1R2T tr
ρ =
S
S + B
I = S + B
HBT interferometry
backﬂash’s peak
coincident events’s “dip”
1_A#1 centre

1_A#2 centre:
• R1=R2=38 kcps=S
• B=15 kcps
• T=1000 s
• tr=100 ns
gcorretta
2( )
t = 0( )= 0.26 ± 0.02
gcorretta
2( )
t = 0( )= 0.085 ± 0.003
Centro 1_B#1:
• R1=R2=25.750 kcps=S
• B=9.500 kcps
• T=1000 s
• tr=100 ns
19
HBT interferometry

Centro 1_A#2:
• R1=R2=38 kcps=S
• B=15 kcps
• T=1000 s
• tr=100 ns
gcorretta
2( )
t = 0( )= 0.26 ± 0.02
gcorretta
2( )
t = 0( )= 0.085 ± 0.003
1_B#1 centre:
• R1=R2=25.750 kcps=S
• B=9.500 kcps
• T=1000 s
• tr=100 ns
19
HBT interferometry

20
Conclusions:
• we have implemented 2 nano-diamond’s SPS fabrication protocols
• both chemical treatments ("A" and "B") are effective
• by SRIM code, we have identified the optimal fluency
• g(2)(t) values extremely promising which confirm the effectiveness of the
production protocols
Prospects:
• make a comparison between chemical treatments of equal duration
• implement the micro-processing of the substrates (possibly transparent and
conductive)
• enter nano-diamonds in special photonic structures
Production’s optimisation &
opto-physics characterisation

Production’s optimisation &
opto-physics characterisation
20
Conclusions:
• we have implemented 2 nano-diamond’s SPS fabrication protocols
• both chemical treatments ("A" and "B") are effective
• by SRIM code, we have identified the optimal fluency
• g(2)(t) values extremely promising which confirm the effectiveness of the
production protocols
Prospects:
• make a comparison between chemical treatments of equal duration
• implement the micro-processing of the substrates (possibly transparent and
conductive)
• enter nano-diamonds in special photonic structures

Thesis Presentation

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