Supplementary Informations
Completely random nanoporous Cu4O3-CuO-C composite thin films for potential
application as multiple channel photonic band gap filter in the telecommunication
wavelengths
Mahua Das1*, C. Bittencourt2, J.J. Pireaux2, S.A. Shivashankar1,
1
Materials Research Centre, Indian Institute of Science, Bangalore-560012
2
University of Namur, LISE laboratory, 61, Rue de Bruxelles, B-5000, Namur, Belgium
* Corresponding author: dmahua2006@gmail.com
Grazing incidence (75o) transmission measurements were carried out using a Fourier
Transform infrared spectrometer in ambient temperature and pressure using a Refractor
Reactor for the films on the stainless steel substrates. The refractor reactor (Figure S1a) is
a chamber made of stainless steel for grazing incidence studies. The angle of incidence is
fixed at 75o and can accommodate samples up to 1”1” with thicknesses of 0.20” to 0.35
“. It can be evacuated to 10-4 Torr, pressurised up to 2 ATM, and has standard ZnSe
windows. In the refractor, the optical beam is defected (15o) to and from the sample via
wedged (10o) ZnSe windows. It is to be noted that, given the geometry of the reactor, in
case of diffuse reflectance by a highly scattering sample, only the reflections that occurs
at the reflection angle of 75o are detected by the detector.
t
r
b
a
b
Figure S1
1.1
a
Log(Rel. Transmittance)
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0
2000
4000
6000
Wavenumber/cm
8000
10000
-1
1.1
b
1.0
Log(Rel.Transmittance)
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0
2000
4000
6000
Wavenumber/cm
8000
10000
8000
10000
-1
1.1
c
1.0
Log(Rel.Transmittance)
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0
2000
4000
6000
Wavenumber/cm
-1
Figure S2 : Grazing incidence infrared spectra of the films
Figures S3a and S3b feature GIXRD patterns recorded at different incidence angles for
the films grown at a substrate temperatures of 350oC (without O2 flow) and 300oC (with
130 sccm of O2) respectively.
a
b
Figure S3 : Grazing incidence XRD patterns for the films at different incidence angle
(designated by different line colours)
The randomness of a random media comprising of dielectric slab in air having random
thickness a and spacing b, cab be expressed in term of the two parameters a and b
as follows
a  a0 (1  2 a r )
[S1]
b  b0 (1   b r )
[S2]
where r is a random number distributed uniformly between -0.5 and 0.5.
Therefore,
1  2 a r
a
 f1
b
1  2 b r
Where f1 
[S3]
a0
is the fill fraction of the dielectric in the random media.
b0
At r = 0.25, we get from equation [S3}
1  2 a (0.25)
a1
[S4]

b1 f1 1  2 b (0.25)
At r = -0.25, we get
1  2 a (0.25)
a2
[S5]

b2 f1 1  2 b (0.25)
b1 f1
[1  2 a (0.25)]
a1
b f
From [S5] we get, 1  2 b (0.25)  2 1 [1  2 a (0.25)]
a2
From [S4] we get, 1  2 b (0.25) 
Adding equations [S6] and [S7] gives
2
b1 f1
b f
[1  2 a (0.25)]  2 1 [1  2 a (0.25)]
a1
a2
2 b1a2 [1  2 a (0.25)]  a1b2 [1  2 a (0.25)]

f1
a1a2
b1a2  a1b2   a (0.5)[b1a2  a1b2 ]
a1a2
 a (0.5)[b1a2  a1b2 ] 
Therefore,  a 
2a1a2
 b1a2  a1b2
f1
2a1a2  f1b1a2  f a a1b2
0.5 f1 (b1a2  a1b2 )
Similarly 1  2 a (0.25) 
1  2 a (0.25) 
[1]
a1
[1  2 b (0.25)] [S8]
b1 f1
a1
[1  2 b (0.25)] [S9]
b1 f1
[S6]
[S7]
Adding equations [S8] and [S9] gives
2 f1 
a1
a
[1  2 b (0.25)]  2 [1  2 b (0.25)]
b1
b2
a1b2 [1  2 b (0.25)]  a2 b1[1  2 b (0.25)]
b1b2

a1b2  a2 b1  0.5 b (a1b2  a2 b1 )
b1b2
b 
2 f1b1b2  a1b2  a 2 b1
0.5(a1b2  a 2 b1 )
[2]
Substituting a1  a0  0.5 a , a2  a0  0.5 a , b1  b0  0.5 b , b2  b0  0.5 b in
the numerator of equation [2] we get
2 f1b1b2  a1b2  a2b1
 2 f1 (b0  0.5 b )(b0  0.5 b )  (a0  0.5 a )(b0  0.5 b )  (a0  0.5 a )(b0  0.5 b )
 2 f1 (b02  0.25 b2 )  (a0 b0  0.5 a b0  0.5 b a0  0.25 a b  a0 b0  0.5 a b0  0.5 b a0  0.25 a b )
 2 f1 (b02  0.25 b2 )  [2a0 b0  0.5 a b ]
2
a0 2
a
b0  2 0 (0.25) b2  2a0 b0  0.5 a b
b0
b0
= 0.5 b ( a  f1 b )
Denominator of equation [2]
0.5a1b2  a 2 b1 
 0.5(a0  0.5 a )(b0  0.5 b )  (a0  0.5 a )(b0  0.5 b )
 0.5(a0 b0  0.5 a b0  0.5 b a0  0.25 a b  a0 b0  0.5 a b0  0.5 b a0  0.25 a b )
 0.5 a b0   b a0 
From equation [2] we get
0.5 b  a  f1 b 
b 
0.5 a b0   b a0 
 a  f1 b
 a b0   b a0
 a  f1 b   a b0   b aa
1  b0  a  a0  f1  b  0
1


1  b0  a   a0  a0  b  0
b0 

1  b0  a  a0b0  a0  b  0
b0
b0 1  b0  a  a0 1  b0  b  0
 a a0

 b b0
[3]
Methods
Thin films of Cu4O3-CuO-C were grown in a vertical flow low pressure cold wall reactor,
built in house. A schematic of the reactor is shown in Figure S4. The reactor is a double
wall, stainless steel (SS304) cylindrical chamber (J), 14 in diameter and 13 high,
covered from the top and bottom by two stainless steel (SS304) flanges(S). Deionised
water at 10oC was circulated through the annular space between the two walls of the
chamber to attain cold wall conditions. The chamber has nine ports (not shown in the
Figure) in total, out of which one is provided with a toughened glass window for visual
inspection. An air-admittance valve (U), used to break the vacuum of the system and
bring it back to normal atmospheric pressure, is also provided.
MFCs
VCu
Ar
O2
Fig
ure
Erro
r!
HTVsNo
text
of
CM spec
ifie
d
styl U
e in
doc
Water out
ume
nt..1
S
T
Water in
G
K
J
A
S
P
Figure S4: Schematic representation of the MOCVD system used for the deposition of
Cu4O3-CuO-C composite thin films
The precursor Cu4(deaH)(dea)(oAc)5.(CH3)2CO, a subliming solid powder, was taken in
a shallow aluminium boat (35 mm  25 mm  10 mm) to facilitate heat transfer and
vapourisation, subsequently was kept in the vapouriser VCu and was heated upto the
desired temperature. The flow of the carrier (Ar) and the reactive gas (O2) was controlled
by two separate mass flow controllers (MFCs). Ar was subsequently passed through the
high
Table 1: CVD conditions employed
temperature valves (HTVs) into the vapouriser for carrying the precursor into the
chamber and the O2 was directly fed into the reactor during deposition. Deposition was
carried out on 316 laser cut stainless steel substrates 1515 mm, which were placed on a
stainless steel substrate holder (G), supported by a stainless steel table at the bottom (A).
The temperature of the substrate was sensed by a thermocouple (K) and was monitored
by a temperature controller (not shown here) from out side. The pressure during the
deposition was sensed by a capacitance manometer (CM) attached to one of the ports of
the reactor and was maintained at the desired value by adjusting a knob attached to the
pump (P).
The different conditions employed in the deposition are tabulated in Table 1.
Substrate
Precursor
Stainless Steel 316
Cu4(deaH)(dea)(oAc)5.(CH3)2CO
Base Pressure
0.2-0.3 Torr
Working Pressure
1 Torr and 3 Torr
Substrate Temperature
300oC and 350oC
Precursor
Vapourisation 65oC
Temperature
Vapouriser line Temperature
80oC
Carrier gas (Ar) flow rate
50 sccm
Reactive gas (O2) flow rate
130 and 150 sccm
Deposition duration
45 mins