introduction into spectroscopic ellipsometry basics, data ... · ellipsometry vs. reflectometry •...
TRANSCRIPT
Introduction into
Spectroscopic Ellipsometry–
Basics, Data Interpretation Considerations and Applications
to PhotovoltaicsThomas Wagner, L.O.T.-Oriel GmbH & Co. KG
University of Twente, February 11th 20101
Outline
Part 1: Theory and Fundamentals
• What is Ellipsometry?
• Light and Polarization
• Measurements
• Optical Constants
• Models and Data Interpretation
Part 2: PV Applications• SiNx AR coatings• Amorphous, microcrystalline, and
poly-Si films• Transparent Conductive Oxides• CdTe and CdS• CIGS• Organic PV layers
2
3
Theory & Fundamentals
• Light
• Materials (optical constants)
• Interaction between light and materials
• Ellipsometry Measurements
• Data Analysis
Electromagnetic Plane Wave• From Maxwell’s equations we can describe a plane wave
Direction
of propagation
X
Y
Z
Electric field E(z,t)
Magnetic field B(z,t)
+−−= ξ
λ
π)v(
2sin),( 0 tzEtzE
Velocity
arbitrary phase
Wavelength
Amplitude
λ
Light
4
5
Intensity and Polarization
• Intensity = “Size” of Electric field.
• Polarization = “Shape” of Electric field travel.
X
Y
ELess
Intense
X
Y EMore Intense
2EI ∝
Different Size
(Intensity)
Same Shape!
(Polarization)
6
What is Polarization?
• Describes how Electric Field travels through space and time.
X
Y
wave1
wave2Z
Describe how materials and light interact.
n = “refractive index”– phase velocity = c/n– direction of propagation (refraction)
k = “extinction coefficient”
– Loss of wave energy to the material
Together “Complex Refractive Index”:
or “Complex Dielectric Function”:
What are Optical Constants?
iknn +=~
21~ εεε i+=
2~~ n=ε
n , k
7
8
Kramers-Kronig Relation
• Real and imaginary parts depend on each other.
• Bumps make wiggles.• Transparent range: Index increases
for shorter wavelengths – normal
dispersion
• When absorption increases, index will “turn” and decrease with decreasing wavelength - anormaldispersion
Frequency (energy)
nk
ε1
ε2( ) ( )
∫∞
′−′
′′+=
0 22
21
21 ω
ωω
ωεω
πωε dP
9
Absorbing region
Absorptions in the various spectral regions have different shapes & root causes.
– Electronic Transitions– Molecular Vibrations– Lattice Vibrations
– Free-carriers Rutile TiO2
UV to IR
ε
Photon Energy (eV)0.03 0.1 0.3 1 3 10
ε 1 2
-50
-38
-25
-13
0
13
25
0
10
20
30
40
50
60
ε1ε2
LatticeVibrations
ElectronicTransitions
UVIR Visible
Transparent
10
plane ofincidence
Ep
Es
Ep
EsEp
Es
Polarized light at interface
• Electric field either parallel (p) or perpendicular (s) to plane of incidence.
• Material differentiates between p- and s- light
Angle of Incidence (°)0 20 40 60 80 100
Ref
lect
ion
0.0
0.2
0.4
0.6
0.8
1.0RpRs
Fresnel Coefficients
• Describes reflection and transmission
• Depends on angle and polarization (p or s)
itti
tiit
pi
rp
nn
nn
E
Er
θθ
θθ
coscos
coscos
0
0
+
−=
=
ttii
ttii
si
rs
nn
nn
E
Er
θθ
θθ
coscos
coscos
0
0
+
−=
=
ttii
ii
si
ts
nn
n
E
Et
θθ
θ
coscos
cos2
0
0
+=
=
itti
ii
pi
tp
nn
n
E
Et
θθ
θ
coscos
cos2
0
0
+=
=
nt
ni
ts,p
rs,p
11
Light-Sample InteractionMultiple reflections in single film lead to aninfinite series
...ee-4i
1010
2
1201
-2i
10120101 +++= ββtrrttrtrrtot
β
β
2
),(12),(01
2
),(10),(01),(12),(01
),(1 i
spsp
i
spspspsp
sptoterr
ettrrr
−
−
−
+=
111 cos2 θ
λπβ n
d
=
FILM PHASE THICKNESS
N2
N1
No
t01t12 t01r12r10t12 t01r12r10r12r10t12
t01r12r10r12t10r10 t01r12t10
12
13
What is Ellipsometry?
• Measures change in polarization of reflected light.
• Sample is defined by reflection of p- and s- polarized light.
plane of incidence
E
E
p-plane
p-plane
s-plane
s-plane
( ) ( ) ρδδ
=Ψ=== ∆− ii
s
p
s
p
in
s
out
s
in
p
out
pee
r
r
r
r
EE
EEsp tan~
~
=
in
s
in
p
s
p
out
s
out
p
E
E
r
r
E
E~0
0~
s
p
r
r=Ψ)tan(
sp δδ −=∆
14
What can SE determine?
Psi (Ψ)Delta (∆)
Film Thickness
Refractive Index
Surface Roughness
Interfacial Mixing
Composition
Crystallinity
Anisotropy
Uniformity
Ellipsometry Measures:Properties of Interest:
Analysis
15
Data Analysis Flowchart
Ellipsometry Advantages
• Repeatable & accurate:– Self-referencing, measures ratio of Ep/Es Thus,
reduced problems with:
• fluctuation of source intensity• light beam spilling over small samples
• Measure two parameters– Ψ and ∆ at each wavelength/angle combination.– increased sensitivity to multiple film parameters
16
Ellipsometry vs. Reflectometry
• Phase information gives Ellipsometry higher sensitivity to very thin films.
Wavelength (nm)200 400 600 800 1000
∆ in
deg
rees
0
30
60
90
120
150
180
Gen E 75° (1)Gen E 75° (2)
Generated Data
200 400 600 800 1000
Ψ in
deg
rees
0
10
20
30
40
Gen E 75° (1)Gen E 75° (2)
Generated Data
Wavelength (nm)200 400 600 800 1000
Ref
lect
ion
0.30
0.40
0.50
0.60
0.70
0.80
Gen sR 0° (1)Gen sR 0° (2)
Generated Data
Wavelength (nm)200 400 600 800 1000
Ref
lect
ion
0.30
0.40
0.50
0.60
0.70
0.80
Gen sR 0° (1)Gen sR 0° (2)
∆
Ψ
R
1nm & 2nm oxide on Si
1nm & 2nm oxide on Si
1nm & 2nm oxide on Si
17
18
Thin Film Interference
• Each reflected wave will have a different phase and amplitude.
• Coherent waves (same freq. and direction) combine constructively/destructively.
r01
t01 r12 t10e-2iβ
t01 r12 r10 r12 t10e-4iβ 0
~n
1~n
2~n
19
Motivation• Data Interpretation:
– Estimate sample based on “raw” data.– Reduce analysis time and improve ability to
identify correct models.
Experimental Data
Wavelength (nm)300 600 900 1200 1500 1800
Ψin
deg
rees
0
5
10
15
20
25
30
Exp E 65°Exp E 75°
Data interpretation not quantitative
20
Role of Optical Constants• Index difference leads to reflection
– Large ∆N � Large Reflection– Small ∆N � Small Reflection
Material 1 Material 2 Reflectance
Air (N=1) SiO2 (N=1.5) ~3.3%
Air (N=1) Si (N=3.5) ~31%
a-Si (N=3.4) Si (N=3.5) ~0.02%
21
Bare Substrates
• What do we expect?
– Psi features follow optical constant structure.
– Psi curves minimize at Brewster condition, but
remain higher when absorbing.
– Delta at 180° or 0°, except when absorbing or in
presence of surface film.
Substrate Optical Constants
• Dielectrics
• Semiconductors
• MetalsIndex of Refraction, N
Wavelength (nm)300 600 900 1200 1500 1800
Inde
x, n
1.4
1.6
1.8
2.0
2.2
SiO2Si3N4
Silicon
Wavelength (nm)200 400 600 800 1000 1200
Inde
x of
ref
ract
ion,
n
Extinction C
oefficient, k
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
NK
Aluminum
Wavelength (nm)
0 300 600 900 1200 1500 1800
Inde
x of
ref
ract
ion,
n
Extinction C
oefficient, k
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0
3
6
9
12
15
18
NK
Substrate
22
23
Dielectrics
• Psi flat and smooth• Delta = 0°,180°- except for surface
films
0.5nm roughness
Wavelength (nm)200 400 600 800 1000 1200
Ψ in
deg
rees
0
5
10
15
20
25
30
Exp E 45°Exp E 55°Exp E 65°Exp E 75°
Wavelength (nm)200 400 600 800 1000 1200
∆ in
deg
rees
0
30
60
90
120
150
180
Exp E 45°Exp E 55°Exp E 65°Exp E 75°
24
Semiconductors
• Psi follows shape of absorption• Delta between 0°or 180°when
absorbing
Wavelength (nm)200 400 600 800 1000 1200
Ψ in
deg
rees
0
10
20
30
40
50
Exp E 55°Exp E 65°Exp E 75°
Wavelength (nm)200 400 600 800 1000 1200
∆ i
n de
gree
s
0
50
100
150
200
Exp E 55°Exp E 65°Exp E 75°
25
Metals
• Significant absorption:– Psi stays near 45°, Delta away from 0° or
180°.
Wavelength (nm)200 400 600 800 1000 1200
Psi
in d
egre
es
36
38
40
42
44
46
65°75°85°
Wavelength (nm)200 400 600 800 1000 1200
Del
ta in
deg
rees
0
30
60
90
120
150
180
65°75°85°
26
“Pseudo Optical Constants”
� <n> & <k> or <ε1> & <ε2>
�Assumption: Optically thick bulk substrate with no surface layers or roughness
where, ρ = tan Ψ ei∆
ϕ = ΑΟΙ
( ) ( )
+
−⋅+⋅==
2
222
1
1tan1sin~
ρ
ρφφε n
Wavelength (nm)200 400 600 800 1000 1200
Ψ in
de
gree
s
∆ in
degree
s
20
25
30
35
40
45
40
60
80
100
120
140
160
Exp Ψ-E 70°Exp Ψ-E 75°Exp ∆-E 70°Exp ∆-E 75°
Wavelength (nm)200 400 600 800 1000 1200
<ε 1>
<ε
2 >
-80
-60
-40
-20
0
20
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Exp < ε1>-E 70°Exp < ε1>-E 75°Exp < ε2>-E 70°Exp < ε2>-E 75°
27
“Pseudo Optical Constants”
• Angle independent way of viewing experimental data.
� All angles give same values implies:Light path is sameOptically thick bulk substrateNo film (or very thin surface layer)
Wavelength (nm)200 400 600 800 1000 1200
<ε1>
<ε
2 >
-80
-60
-40
-20
0
20
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Exp < ε 1>-E 70°Exp < ε 1>-E 75°Exp < ε 2>-E 70°Exp < ε 2>-E 75°
28
Thin Films
• “Very Thin” ⇒ thickness < 100 Å
• determining thickness when OC’s are known– SE deals with this well
• determining OC’s– very difficult, if not impossible
29
Determining Thickness
• mainly Delta (Phase) is sensitive to very thin films– 20, 40, 65, 80, 100 Å
30
Very Thin Film Index?• Correlation prevents exact determination, beyond
whether higher or lower than substrate index.
Wavelength (nm)300 400 500 600 700 800 900
∆in
deg
rees
-30
-20
-10
0
10
20
n=1.25n=1.35n=1.45
n=1.55n=1.65n=1.75
5nm coating on Glass
Transparent Films
• Thicker films produce more interference oscillations.
500nm
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψin
deg
rees
0
20
40
60
80
100
Exp E 75°
5 micron Oxide
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψin
deg
rees
0
20
40
60
80
100
Exp E 75°
100nm Oxide
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψin
deg
rees
0
20
40
60
80
100
Exp E 75°
31
Thickness Effects
• As thickness increases:*Interference shifts to red*Peaks closer together
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψin
deg
rees
0
20
40
60
80
100
T
32
33
Transparent Films
• Dispersion Relationship, such as Cauchy, can be used to reduce the number of “fit” parameters.
n(λ)=A+B/λ2+C/λ4
k(λ)=0
Wavelength (nm)200 400 600 800 1000 1200
Inde
x of
ref
ract
ion
'n'
1.44
1.47
1.50
1.53
1.56
1.59
1.62
1.65
34
Amplitude (An)
• Adjust the An parameter to the approximate index.
42)(λλ
λ nnn
CBAn ++=
Wavelength (nm)300 400 500 600 700 800 900
Inde
x
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
An = 2.50An = 2.25An = 2.00
An = 1.50An = 1.75
35
Dispersion (Bn and Cn)
• Bn & Cn provide curvature versus wavelength.
Wavelength (nm)300 400 500 600 700 800 900
Inde
x
1.25
1.50
1.75
2.00
Bn = 0.020Bn = 0.010
Bn = 0.000Bn = 0.005
42)(λλ
λ nnn
CBAn ++=
Bn = -0.01
Effect of Film Index
Index difference affects oscillations (75° AOI)
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψin
deg
rees
0
20
40
60
80
100n=1.5n=1.75n=2.0
n=2.25n=2.5
n=2.75n=3.0
n=3.25n=3.5
n=3.75n=4.0
36
37
Effects of Dispersion
• Oscillations are primarily due to thickness. Dispersion will affect oscillation position and amplitude slightly.
No Dispersion
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψ in
deg
rees
0
10
20
30
40
50
0 n=4 1 mm1 n=2 500 nm
With Dispersion in Film
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψ in
deg
rees
0
10
20
30
40
50
0 n=4 1 mm1 user 500 nm
38
Multilayers- Envelope
• Oscillations for multilayers is a combination of each film envelope.
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψ in
deg
rees
0
20
40
60
80
MultilayerOxide OnlyNitride OnlySubstrate
0 substrate 1 mm1 oxide 500 nm2 nitride 200 nm
39
Multilayer Example
• Both oscillation patterns are superimposed!
Multilayer Example
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψ in
deg
rees
0
20
40
60
80
n=4 1 mmn=3 1000 nmn=1.5 200 nm
40
Absorbing Thin Film
• If light is absorbed before returning to surface, only top reflection is ‘seen’ (Film appears as Substrate)
Wavelength (nm)120 150 180 210 240 270 300
∆in
deg
rees
-50
0
50
100
150
200
250
300
41
Multilayer (Absorbing-Transparent)
• If 2-layer, but 1 is absorbing, then:
0 si 1 mm1 sio2 3000 nm2 a-si 300 nm
Generated Data
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψ in
deg
rees
0
10
20
30
40
50
60Generated Data
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψ in
deg
rees
0
20
40
60
80
100
0 si 1 mm1 a-si 300 nm2 sio2 3000 nm
42
PV Applications
• SE is applied to most PV thin films:
– SiNx AR coatings
– Amorphous, microcrystalline, and poly-Si films
– Transparent Conductive Oxides
– CdTe and CdS
– CIGS
– Organic PV layers
– …
43
Ellipsometric study of Photovoltaics
• Measurement challenges:– Textured/ Rough surface– Low reflection– Large samples– Industrial integration
• Modeling considerations:– Rough surfaces, Rough interfaces, Rough substrates– Parameter correlation
• Applications
44
Wafer
treatment
Morphology
Polished, c-Si Smooth
Alkaline etched, c-Si
Alkaline etched,multi c-Si
Acid etched,multi c-Si
As-cut,multi c-Si
20 µm
50 µm
50 µm
20 µm
Textured Si coated with SiNy
Measurement Challenge:Textured surfaceHigh scatteringSpecular R ~ 0
Solution:Sample tilting mount
Improved light source and detection system
Including scattering factor
M. F. Saenger, M. Schubert, J. Hilfiker, J. Sun, J. A. Woollam, M. Schädel, IMRC 2008
Textured Si Wafer
M-2000X with Intensity Optimizer
45
46
Large Area Mapping
ACCUMAP-SE
Flying-SE
47
Modeling Considerations
• Modeling considerations for PV thin films:
– SiNx AR coatings
– Amorphous, microcrystalline, and poly-Si films
– Transparent Conductive Oxides
– CdTe and CdS
– CIGS
– Organic PV layers
Rough surfaces, Rough interfaces, Rough substrates, High absorption, Grading, Anisotropy, Superstrates, Complex sample structure, Parameter correlation, ..
Thin Film Interference
0~n
1~n
2~n
Transparent -
oscillations
Photon Energy (eV)1.8 2.1 2.4 2.7 3.0 3.3 3.6
Ψ in
deg
rees
0
5
10
15
20
25
30transparent
Absorbing-oscillation
suppressed
0~n
1~n
2~n
Photon Energy (eV)1.8 2.1 2.4 2.7 3.0 3.3 3.6
Ψ in
deg
rees
0
5
10
15
20
25
30transparentabsorbing
Rough Surface –
shifts in data
0~n
1~n
2~n
Photon Energy (eV)1.8 2.1 2.4 2.7 3.0 3.3 3.6
Ψ in
deg
rees
0
5
10
15
20
25
30transparentabsorbingrough surface
48
49
Thickness determination - UV/VIS
• Difficult in UV/ Visible range due to high absorption/ surface roughness
Experimental Data
Wavelength (nm)200 300 400 500 600 700 800
Ψ in
deg
rees
∆ in degrees
5
10
15
20
25
30
-100
-50
0
50
100
150
200
250
Exp Ψ-Eb 65°Exp ∆-Eb 65°
Wavelength (nm)200 300 400 500 600 700 800
Inde
x of
Ref
ract
ion
'n'
Extinction C
oefficient 'k'
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0.0
0.5
1.0
1.5
2.0
2.5
nk
Thickness determination- Near Infrared (NIR) or Infrared (IR)
Transparent region in NIR/IR spectra
easy to get thickness!
Experimental Data
Wavelength (nm)200 400 600 800 1000 1200 1400 1600
Ψ in
deg
rees
∆ in degrees
5
10
15
20
25
30
-100
0
100
200
300
Exp Ψ-E 65°Exp ∆-E 65°
Wavelength (nm)0 300 600 900 1200 1500 1800
Inde
x of
Ref
ract
ion
'n'
Extinction C
oefficient 'k'
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0.0
0.5
1.0
1.5
2.0
2.5
nk
UV –VIS - NIR
1
1.5
2
2.5
3
3.5
4
0 4000 8000 12000 16000 20000
Wavelength (nm)
Ind
ex
of
refr
ac
tio
n,
N
0
0.5
1
1.5
2
2.5
Ex
tin
cti
on
co
eff
icie
nt,
kn k
50
51
Modeling of Rough Surfaces
• Bruggeman Effective Medium Approximation (EMA)– Mix the optical constants of surface layer with void
Rough Surface EMA approximation
t
52
SiNx AntiReflection CoatingsΨ
in d
egre
es
0
10
20
30
40
50Textured Si - Exp DataTextured Si - MODELSiNx - Exp DataSiNx - MODEL
Wavelength (nm)
200 400 600 800 1000
∆in
deg
rees
-40
-20
0
20
40
60
80
Insert: SEM graph
SiNx Optical Constants
Wavelength (nm)200 400 600 800 1000
Inde
x of
Ref
ract
ion,
n
Extinction C
oefficient, k
1.84
1.86
1.88
1.90
1.92
1.94
1.96
0.00
0.05
0.10
0.15
0.20
nk
0 ema si_jaw/23% void 1 mm1 sin-tauc lorentz 70.500 nm
With Scattering Factor
53
Amorphous, Microcrystalline, and Poly-Crystalline Silicon
Photon Energy (eV)1.0 2.0 3.0 4.0 5.0 6.0
Imag
(Die
lect
ricC
onst
ant)
, ε2
0
10
20
30
40
50
a-Si70% Poly-Si85% Poly-Sic-Si
For high crystalline %, the peak is narrower and eventually separates into two distinct regions.
54
Transparent Conductive Oxides
∆in
deg
rees
0
100
200
300Model Fit Exp Eb 55°Exp Eb 65°Exp Eb 75°
Wavelength (nm)0 300 600 900 1200 1500 1800
Ψin
deg
rees
0
10
20
30
Glass Substrate
SnO2
SiO2
SnO2:F
30nm
320nm
23nm
� TEC-15 Glass– Characterize Multi-Layer
TCO structure– TCO intentionally rough -
hazy for light trapping
55
Indium Tin Oxide
ITO Optical Constants during Deposition
0
0.5
1
1.5
2
2.5
400 600 800 1000 1200 1400 1600Wavelength in nm
Ind
ex
of
Refr
acti
on
, n
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Ex
tin
cti
on
Co
eff
icie
nt,
k
n, Middle of depositionn, After depositionn, After annealingk, Middle of depositionk, After depositionk, After annealing
• NIR absorption used to monitor conductivity
56
CdTe / CdS on Tec-15 Glass
Photon Energy (eV)0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
<ε 1
>
-3
0
3
6
9
12
15
Model Fit Exp Eb 60°Exp Eb 75°
Photon Energy (eV)0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
<ε 2
>
-9
-6
-3
0
3
6
9
Model Fit Exp Eb 60°Exp Eb 75°
CdTe 1458nm
CdS 210nm
Tec-15 Glass
CdTe –SEM micrograph-Courtesy: Nicola Romeo, University of Parma,
INFM, & ARENDI S.p.A. IMRC 2008
57
CdTe and CdS Films
• Measure optical constants with changing morphology and process conditions.
CdTe Optical Constants
Photon Energy (eV)0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0R
eal(D
iele
ctri
c C
onst
ant)
, ε 1
Imag(D
ielectric Constant),
ε2-3
0
3
6
9
12
0
2
4
6
8
10
12
ε1ε2
CdS Optical Constants
Photon Energy (eV)0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0R
eal(D
iele
ctric
Con
stan
t),
ε 1
Imag(D
ielectric Constant),
ε2
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0ε1ε2
58
CIGS
A.M. Hermann et al. “Fundamental studies on large area Cu(In,Ga)Se2 films for high efficiency solar cells”, Solar Energy Materials & Solar Cells 70 (2001) 345.
59
Organic Solar Cells• Measurement similar to OLED• Films may exhibit anisotropy• SE + Transmission fit, OLED film:
60
Organic Solar Cell Materials
• PEDOT:PSS• Multi-Sample fit:
61
Organic Solar Cell Materials
• P3HT / 300nm SiO2 / Si• Multi-Sample fit:
Generated and Experimental
Photon Energy (eV)0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
Ψ in
deg
ree
s
0
20
40
60
80
100Model Fit Exp E 45°Exp E 55°Exp E 65°Exp E 75°
Generated and Experimental
Photon Energy (eV)0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
∆ in
de
gre
es
-100
0
100
200
300
Model Fit Exp E 45°Exp E 55°Exp E 65°Exp E 75°
P3HT Optical Constants
Wavelength (nm)0 300 600 900 1200 1500 1800
Inde
x of
Ref
ract
ion
'n'
Extinction C
oefficient 'k'1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4nxynzkxykz
62
PV Summary
• SE has many uses toward PV thin films:
– SiNx AR coatings
– Amorphous, microcrystalline, and poly-Si films
– Transparent Conductive Oxides
– CdTe and CdS
– CIGS
– Organic PV layers
– …
63
Further References on Ellipsometry
1. Hiroyuki Fujiwara, Spectroscopic Ellipsometry: Principles and Applications, John Wiley & Sons, 2007.
2. Handbook of Ellipsometry, Tompkins and Irene, eds., William Andrew Publishing, NY, 2005.
3. H. G. Tompkins, and W.A.McGahan, Spectroscopic Ellipsometry and Reflectometry, John Wiley & Sons, New
York, 1999.
4. R.M.A. Azzam, and N.M.Bashara, Ellipsometry and Polarized Light, North Holland Press, Amsterdam 1977,
Second edition, 1987.
ICSE Conference Proceedings:
1. Thin Solid Films Vol. 455-456, (2004) M. Fried, K. Hingerl, and J. Humlicek, Editors, Elsevier Science.
2. Thin Solid Films Vol. 313-314 (1998) R.W.Collins, D.E.Aspnes, and E.A. Irene, Editors, Elsevier Science.
3. Spectroscopic Ellipsometry, A.C.Boccara, C.Pickering, J.Rivory, eds, Elsevier Publishing, Amsterdam, 1993.