Optical characterization
of
mateterials and devices
for
micro and optoelectronic applications
Author: Massimo Gagliardi
PhD student to "Mediterranea" University of Reggio Calabria
IMM-CNR sect. Naples
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
In-guide pump and probe characterization of
photoinduced absorption in hydrogenated
amophous silicon thin films
15
a-SiC:H
30
CH4
0 sccm
25 sccm
35 sccm
M (%)
M (%)
10
20
5
10
k329
k331
0
0.0
0.1
0.2
0.3
0.4
-2
Ivis (mW mm )
0.5
0
0.0
0.6
V  Vill
M 
V
0.1
0.2
0.3
0.4
-2
Ivis (mW mm )
0.5
0.6
V0 e  L  V0 e    L
 L
M

1

e
V0 e  L
 vis
 probe = 1.55  m
y
0
a -Si:H
x
c -Si
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Ellipsometry
tecnique for studying surfaces and thin films



SE gives two independent experimental values Δ and  which are function of the
wavelength l and of the incidence angle AI [1]
R
tg ( )ei  p
Rs
This technique is model dependent, i.e. it does not give directly the physical quantities.
A fitting procedure is required to match the theoretical model, which has to be previously
built, to the experimental data [2].

Optical properties
 Refractive index (n) and extinction coefficient (k) from the far-UV to near-IR for materials,
graded and anisotropic layers

Thickness
 Thin film measurement from a few angstroms to several microns
 For single layer or complex multilayer stacks (layer thickness, surfaces and interfaces
roughness)

Material properties
 Composition
 Porosity
 Film uniformity by area and depth
Riunione Annuale GE 2006
References
[1[ E.Dumont, B.Dugnoille, S.Bienfait,Thin solid films, 353, 93
(1999)
[2] H.G.Tompkins, W.A.McGahan, "Spectroscopic ellipsometry
and reflectometry"
Ischia, 21-23 giugno 2006
Applications
Characterized materials
 Isotropic materials
– Sputtered ZnO
– Sputtered LiNbO3
 Nanostruttured materials
– Porous silicon
 Anisotropic materials
– Liquid Crystal
d2
roughness
d1
(n1,k1)
substrate (n0,k0)
(Cauchy, Lorentz,…)
(n,k) = f(lambda) for the TiO2 layer
3.2
0.5
3.1
0.45
3
0.4
2.9
0.35
2.8
0.3
2.7
0.25
2.6
0.2
Im(Index)
Re(Index)

0.15
2.5
0.1
2.4
0.05
2.3
400
Riunione Annuale GE 2006
500
600
lambda (nm)
700
800
0
Ischia, 21-23 giugno 2006
Spectroscopic Ellipsometric study on ion
implanted and laser annealed highly doped
shallow junctions on silicon
15
21
15
2
as implanted
2
720mJ/cm , 10 p
2
870mJ/cm , 10 p
20
10
2
As 1x10 /cm 30 keV + ELA 10 pulses
As 1x10 /cm 30keV + ELA 10 pulses
2
870mJ/cm (As=1.5E15)
20
10
2
720mJ/cm (As=1.3E15)
-3
carrier concentration [cm ]
-3
Concentration [cm ]
10
19
10
18
10
17
10
0.00
19
10
18
10
17
10
16
0.05
0.10
0.15
0.20
0.25
10
0.30
0.00
depth [m]
0.05
0.10
0.15
0.20
0.25
0.30
depth [m]
36.000
180.000
34.000
175.000
32.000
170.000
30.000
1
Void.ref
C-si_isa.ref
28.000
165.000
26.000
160.000
24.000
155.000
22.000
S
¶ (ß)
C-si_isa.ref
150.000
£ (ß)
20.000
145.000
18.000
140.000
16.000
135.000
14.000
Dispersion Model
130.000
12.000
125.000
10.000
8.000
120.000
6.000
2
f j 20 j
j 1
 20 j   2  i j
       

115.000
2p
400
600
800
1.000
Wavelength (nm)
1.200
1.400
1.600
 2  id
0.850
Lorentz oscillator
Drude
-0.200
0.800
0.750
-0.250
0.700
-0.300
0.650
0.600
-0.350
1
Lorentz-Drude.dsp
0.550
-0.400
0.500
0.450
Ic -0.450
Is
0.400
S
C-si_isa.ref
-0.500
0.350
0.300
-0.550
0.250
0.200
-0.600
0.150
-0.650
0.100
0.050
-0.700
0.000
400
Riunione Annuale GE 2006
600
800
1.000
Wavelength (nm)
1.200
1.400
Ischia, 21-23 giugno 2006
1.600
THANKS
FOR YOUR
ATTENTION
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006