optical & structural properties measurements of material(s
TRANSCRIPT
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Malik Nadeem Ahmed University of Padova, Italy
EXTATIC Welcome Week 2017 CTU, Prague, Czech Republic
22-24th September, 2017
Optical & Structural Properties Measurements of Material(s) in EUV spectral Range
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EXTATIC EMJD Detail Name: Nadeem Ahmed Malik Home Institution: UNIPD, Italy Host Institution: UCD, Ireland EXTATIC Cohort: 2016 Lead Supervisor: Prof. Piergiorgio Nicolosi Departement of Enginerring and Information LUXOR-CNR-IFN University of Padova, Italy
Co- Supervisor: Dr. Paola Zuppella CNR - Institute for photonics & nanotechnologies
Host Supervisor: Prof. Gerry O’Sullivan University College Dublin, Dublin, Ireland
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• PhD Research Project
• PhD Work Breakdown
• Research Activites – Selection of material & motivation
– Literature review (materials)
– Theoretical modeling/ simulations
– Experimentation and data analysis
• Research Outcomes First Year
• Future Planed Activities
• Acknowlegments
Outline
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PhD Research Project
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Proposed Research Topic • Topic:
Optical and structural properties measurements of material(s)/compounds in Extreme Ultraviolet Spectral Range
• Abstract:
The aim of the thesis is to characterize the optical properties of element(s)/ compounds, not yet well known in EUV spectral band, applying different diagnostic techniques, based on reflection, absorption and polarimetric measurements, taking into account the polarization of radiation.
Suitable composite structures will be studied in order to emphasize the effect due to the coupling of different materials like stress and interface characteristics.
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PhD Breakdown
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PhD Breakdown
Breakdown
PHD
Research Work
Host University Home University
Course Work
EXTATIC Requirement
University Requirement
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Course Work Progress
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• Enrolled in the Doctorate Program for 3 years at Departement of Information Engineering, University of Padova,Italy
As a a fulfilment requirment (20 Credits) for the PhD studies in Padova Univesrity and EXTATIC I have attended following courses during the first year:
1. Foundation Module (EXTATIC+ DEI Program)
2. EUV Optics (EXTATIC + DEI Program)
3. Statistical Methods. (DEI Program)
4. Physics and operation of heterostructure-based electronic and optoelectronic devices. (DEI Program)
5. Italian Language module (EXTATIC)
Course Work Progress
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Conferences/ Seminars
• Seminars
– Functional materials for astronomical instrumentation by Dr Andrea Bianco (INAF – Osservatorio Astronomico di Brera)
• International Conferences
– EXTATIC WELCOME WEEK (ICTP, Trieste, Italy)
– Graphene 2017 (March 28-30), Barcelona, Spain
(Largest European Conference on Graphene & 2D Materials)
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Research Activities First Year
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Research Activities • Scientific background and materials selection
• Modeling and simulation of materials optical throughputs in the EUV spectral range (IMD software).
• Implementation and validation of a table top polarimetric facility for the EUV spectral range EUV ellipsometric studies of SiO2/Si.
• EUV ellipsometric studies of graphene/SiO2/Si monolayer and trilayer. Experiments were performed, the analysis is in process.
• Proposals submission at BEAR beam line (ELETTRA synchrotron) and Bessy II beamline, Berlin for optical characterization of materials of interest in the complete EUV spectral range. Proposal has been accepted as a top ranked proposal and the beam time allotted for experiments in October 2017.
• Research article writing is in process based on the above studies.
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Literature Review & Material Selection
Research Activities
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• Material Selection 2D MoS2, Graphene and SiO2 has been selected as potential materials for study particularly in EUV spectral band based on the literature review.
• Motivation – To date the optical properties of 2D MoS2 & Graphene in EUV and soft X- ray
region not well known.
– There are some studies related to graphene but only in the framework defects induced by the EUV radiation.
– Knowledge of optical properties of mono/ few layer MoS2, & Graphene in the EUV region many potential applications can be suggested for different technological domains e.g.
• Space optical components
• Lithography masks, pellicles, protective layers etc.
• Enhanced optical elements for free electron lasers & fourth generation light sources.
Literature Review & Material Selection
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Properties of Materials Graphene is the best known among the
2D materials with following
• Unique electrical properties, e.g. – high conductivity,
– zero band gap
– semi metallic behavior,
– massless Dirac fermions, ballistic transport
[1, 2],
• Chemically inert
• Thermal & chemical stability in harsh
environments,
• High mechanical strength
• Impermeability to ion diffusion [3, 4].
• Impermeable to gases as small as
Helium [5]
• Oxidation resistance [6].
2D MoS2 is most promising materials for
flexible, transparent electronic device
components. [7,8].
• Ultrahigh photoresponsivity ~ 6 times that
of graphene,.
• Direct bandgap (sensitive to most of the
visible light.
• Optical Bandgap is tunable by thickness
control [9].
• High mechanical stiffness (Young's modulus
of 270 ± 100 Gpa)
• Breaking stress of 22 ± 4 GPa. [10,11].
• Protective against oxidation and corrosion.
[12] .
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Theoretical Modeling
Research Activities
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Theoretical Modeling: MoS2 • Following is some comparison of the reflectance spectra of MoS2/SiO2/Si
and SiO2/Si at wavelength 40nm obtained by IMD simulation tool.
0 20 40 60 80 100
0.0
0.2
0.4
0.6
0.8
1.0
0 20 40 60 80 100
0.0
0.2
0.4
0.6
0.8
1.0
1
Rp
Theta (Deg)
Rp MoS2 @ 40 nm
Rp SiO2 @ 40 nm
0 20 40 60 80 100
0.0
0.2
0.4
0.6
0.8
1.0
0 20 40 60 80 100
0.0
0.2
0.4
0.6
0.8
1.0
2
Rs
Theta(Deg)
Rs MoS2 @ 40nm
Rs SiO2 @ 40nm
0 20 40 60 80 100
0.00
0.05
0.10
0.15
0.20
0 20 40 60 80 100
0.00
0.05
0.10
0.15
0.203
RpM
oS
2-R
pS
iO2
Theta (Deg)
Rp MoS2-Rp SiO2
Fig. Reflectance spectra (1) Rp of MoS2/SiO2/Si and SiO2/Si (2) Rs of MoS2/SiO2/Si and SiO2/Si (3) Difference Rp of MoS2/SiO2/Si and SiO2/Si; angle [5, 85°] @40nm.
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Theoretical Modeling: MoS2 • Following is some comparison of the reflectance spectra of MoS2(mono,
bi, trilayer )/SiO2/Si and SiO2/Si at angle 70°by IMD simulation tool.
Fig. Reflectance spectra (1) Rp of MoS2 (mono,bi,trilayer)/SiO2/Si (mono, bi, trilayer MoS2)and SiO2/Si (2) Rs of MoS2/SiO2/Si and SiO2/Si (3) Difference Rp of MoS2/SiO2/Si and SiO2/Si; angle [5, 85°] @40nm.
0 5 10 15 20 25 30 35 40 45
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0 5 10 15 20 25 30 35 40 45
0.0
0.1
0.2
0.3
0.4
0.5
0.62
Rs @
70
0
Wavelength (nm)
Rs MoS2 0.68@ 70deg
Rs MoS2 2.04@ 70deg
Rs MoS2 3.4@ 70deg
Rs SiO2 @ 70deg
0 5 10 15 20 25 30 35 40 45
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0 5 10 15 20 25 30 35 40 45
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
1
Rp
@ 7
00
Wavelength (nm)
Rp MoS2 0.68 @ 70deg
Rp MoS2 2.04 @ 70deg
Rp MoS2 3.4 @ 70deg
Rp SiO2 @ 70deg
0 5 10 15 20 25 30 35 40 45
0.00
0.05
0.10
0.15
0.20
0.25
0 5 10 15 20 25 30 35 40 45
0.00
0.05
0.10
0.15
0.20
0.25
3
Rp
Mo
S2
3.4
-Rp
SiO
2@
70
0
Wavelength (nm)
RpMoS2 3.4-RpSiO2
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Theoretical Modeling: Carbon/graphene
• Following is some comparison of the reflectance spectra of C/SiO2/Si at different wavelength 40, 30, 13.5nm obtained by IMD simulation tool.
Fig. Reflectance spectra (left) R of C/SiO2/Si at fixed wavelength (right) Difference Rp of C/SiO2/Si and SiO2/Si; angle [5, 85°] @40nm.
0 20 40 60 80 100
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 20 40 60 80 100
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Re
fle
cta
nce
Theta (Deg)
RC @ 40nm
RC @ 30nm
RC @13.5nm
0 20 40 60 80 100
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0 20 40 60 80 100
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
RC
p-R
pS
iO2
@4
0n
m
Theta (Deg)
RCp-RpSiO2 @40nm
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Experimental Setup for Reflectometry & Polarimetric Measurement at IFN, Padova
Research Activities
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Setup for Reflectometry and Polarimetric studies
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Experimental Setup
Real view of the FUV and EUV normal incidence reflectometer at CNR-IFN Padova.
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Four Reflection Polarizer
Fig. (a) Design of four reflecting mirrors polarizer (b) all mirrors consisting of
200 nm layer of Au on Si substrate (c) Overall shape of four reflection
polarizer attached to the rotation stage. (courtesy of AHMED)
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Brief Theoretical Background
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Theoretical Background
Light Beam can be characterized in terms of the Stokes parameters that are the components of the
Stokes vector S= (S0 S1 S2 S3). The effect of simple and complex optical elements can be described
by the Mueller matrix M(4x4) associated to the system.
M.SS'
Muller matrix of four reflection polarizer is 8 88 8
s p s p
8 88 8
s p s p
FRP
44
s p
r r r r 0 0
2 2
r r r r 0 0M
2 2
0 0 r r 0
0
44
s p
0 0 r r
rs2 and rp
2 are the electric field amplitude of the reflection of gold mirror.
Mathematical representation of rotated polarizer 8 8 88 8 8
s p s p s p
8 88 8
s p s p 2 4 4 2
r r r r r r cos2 sin 2 0
2 2 2
r r r rcos 2 cos 2 sin 2
2 2s pr r
88
s p 4 4 2
8 8 88 8 8
s p s p s p4 4 2 4 4 2
r r cos2 .sin 2 sin 2 .cos2 0
2
r r r r r rsin 2 sin 2 .cos2 - cos2 .sin2 sin 2 cos 2 0
2 2 2
0
s p
s p s p
r r
r r r r
4 4 0 0 s pr r
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Theoretical Background
Then the output intensity of the beam impinging the sample and passing through the analyzer S'=R(-Ѳ)×M(FRP)×R(Ѳ)×M(WR)×S
8 2 8 28 2 8 2
0
8 2 8 28 2 8 2
1
8 88 8
2 3
cos 2
1' cos 2
4
2 cos sin 2 2 sin sin 2
s p s p s p s pR RR R
s p s p s p s pR RR R
R R R R
s p s P s p s P
r r r r r r r r S
S r r r r r r r r S
r r r r S r r r r S
Output of the light beam at the detector after reflecting from the sample and passing through the
analyzer.
Ellipsometric Parameters:
relative phase change
relative amplitude change
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Experimental Results
Research Activities
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Polarimetric Results: SiO2
0 50 100 150 200 250
-500
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
0 50 100 150 200 250
-500
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
Co
un
ts (
Arb
itra
ry U
nits)
Analyzer Angle (Degree)
50 Degree @121.6nm
60 Degree @121.6nm
65 Degree @121.6nm
70 Degree @121.6nm
75 Degree @121.6nm
80 Degree @121.6nm
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Reflectometry Data: SiO2
0 20 40 60 80 100
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.90 20 40 60 80 100
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Re
fle
cta
nce
(A
rbitra
ry u
nits)
Incidence angle (Degrees)
RsSiO
2/Si
RpSiO
2/Si
-10 0 10 20 30 40 50 60 70 80 90 100
0.2
0.4
0.6
0.8
1.0
-10 0 10 20 30 40 50 60 70 80 90 100
0.2
0.4
0.6
0.8
1.0
Ra
tio
=r p
/rs=
(S
qrt
(R
p/R
s))
Incidence angle (Degrees)
Ratio SiO2/Si
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Polarimetric Results: SiO2
-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
0.0
0.2
0.4
0.6
0.8
1.0
-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
0.0
0.2
0.4
0.6
0.8
1.0
No
rma
lize
d In
ten
sity (
a.u
.)
Rotation angle (Radian)
Exp Data 50
Fitted 50
Direct at 45
50 55 60 65 70 75
0
20
40
60
80
100
120
140
50 55 60 65 70 75
0
20
40
60
80
100
120
140
Ph
ase
Diff (0
)
Incidence angle [degree]
Phase Diff Matlab
Phase Diff IMD @122nm
Fig. Phase difference retrieved by using a Matlab code based
on the experimental data (black) and phase difference by IMD
simulations (red).
Fig : Polarization measurements: experimental (black) and fitted
(red) data against the incidence angle (blue) shows direct signal
acquired without the sample and by rotating the polarizer.
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Experimental Data SiO2
Fig. Ratio with error bars: experimental ratio (black+), Matlab fitted ratio (green+) and IMD based modeling ratio
(blue+) against the incidence angle (50°- 80°).
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Summary of polarimetric data SiO2
Incidence
angle
Ratio
(Matlab
code)
Ratio
(exp)
Ratio
(IMD)
@121.6nm
Phase
(Matlab
code)
Phase
(IMD)
50 0.46 0.45 0.51 13 14
60 0.25 0.27 0.32 28 29
65 0.16 0.18 0.23 45 48
70 0.14 0.18 0.18 91 87
75 0.24 0.27 0.24 136 134
80 0.41 0.43 0.40 147 157
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Polarimetric Data: Graphene
0 50 100 150 200 250
-500
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
0 50 100 150 200 250
-500
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
Co
un
ts (
Arb
itra
ry U
nits)
Analyzer Angle (Degree)
50 Degree @121.6nm
60 Degree @121.6nm
65 Degree @121.6nm
70 Degree @121.6nm
75 Degree @121.6nm
80 Degree @121.6nm
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Reflectometry Data Graphene
0 10 20 30 40 50 60 70 80 90
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 10 20 30 40 50 60 70 80 90
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Re
fle
cta
nce
Incidence Angle (Degree)
Rs
Rp
0 10 20 30 40 50 60 70 80 90
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 10 20 30 40 50 60 70 80 90
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Ra
tio
= r
p/r
s
Incidence Angle (Degree)
Ratio= rp/r
s=Sqrt (R
down/R
up)
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Research outcome_first year • Successful execution of planned activities
• Validation and successful Implementation of a table top polarimetric facility for EUV ellipsometric studies of SiO2/Si and Graphene/ SiO2/Si.
• Research article writing is in process based on the above studies.
• Experimental proposal for beam time at Elettra synchrotron facility is accepted as a top ranked proposal and beam time allotted for experiments in October 2017.
• Poster Presentation accepted at the PTB's 304. Seminar "VUV and EUV Metrology". October 19, 2017.
• Publications:
– 02 conference publications (SPIE)
– 01 article is submitted in an international journal
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Future Planed Activity • Continue writing of manuscript(s) based on the data collected
first year.
• Experimentation for data collection at Elettra synchrotron facility
• Sample preparation/ acquisition for future possible experiments at synchrotron facilities at Berlin and Trieste.
• Data analysis and possible research publication (s)
• Remaining EXTATIC modules of courses will be taken
• Mobility will be planned
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References
1. K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, Nature 438(7065), 197–200 (2005).
2. Y. B. Zhang, Y. W. Tan, H. L. Stormer, and P. Kim, Nature 438(7065), 201–204 (2005).
3. W.A. de Heer, C. Berger, X. Wu, P.N. First, E.H. Conrad, X. Li, T. Li, M. Sprinkle, J. Hass, M.L. Sadowski, M. Potemski, and G. Martinez, Solid State Commun. 143(1–2), 92 (2007).
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Acknowledgment I would like to express my sincere thanks and gratitude to:
• The Education, Audiovisual and Culture Executive Agency (EACEA) Erasmus Mundus Joint Doctorate Program and EXTATIC management.
• I would like to express my deepest gratitude to Prof. Piergiorgio
Nicolosi and Dr. Paola Zuppella for their guidance, and great cooperation.
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THANK YOU FOR YOUR ATTENTION