Internati
o
nal
Journal of Ele
c
trical
and Computer
Engineering
(IJE
CE)
V
o
l.
6, N
o
. 2
,
A
p
r
il
201
6, p
p
.
46
8
~
47
3
I
S
SN
: 208
8-8
7
0
8
,
D
O
I
:
10.115
91
/ij
ece.v6
i
2.9
064
4
68
Jo
urn
a
l
h
o
me
pa
ge
: h
ttp
://iaesjo
u
r
na
l.com/
o
n
lin
e/ind
e
x.ph
p
/
IJECE
Visual and Surface Properties of
CdTe Thin Films on CdS/FTO
Glass Substrates
Ram
y
a K, Yu
var
a
j
a
T
Department o
f
Electrical and
Electr
onics Engin
e
ering, Sri Sa
i Ram College of
En
gineer
ing, Bang
alore, Ind
i
a
Article Info
A
B
STRAC
T
Article histo
r
y:
Received Sep 23, 2015
Rev
i
sed
No
v
13
, 20
15
Accepte
d Dec 5, 2015
Cadm
ium
tellur
i
de (CdT
e) th
i
n
f
ilm material was deposited
ontop of
Cadmium Sulfide (CdS) substrate usi
ng vacuum evaporation tech
nique.
The
sample was characterized using
X-ra
y
diffractio
n (XRD)
and UV-VIS-NIR
spectroscop
y.
X
R
D studies rev
e
aled
tha
t
th
e sa
m
p
le was pol
yc
r
y
sta
llin
e
in
nature
. Th
e S
E
M
im
age s
howed that
the s
a
m
p
l
e
is
colum
n
ar
in
s
t
ructure
and
the
grains
ar
e
uniform
.
Optical
ba
nd ga
p
of t
h
e
CdTe
t
h
in fi
l
m
wa
s
es
tim
a
t
ed from
t
r
ans
m
it
ta
nc
e an
d refl
e
c
tance data and it was fou
nd 1.53
eV.
The s
t
ru
ctu
r
a
l
,
opti
c
al
and s
u
r
f
a
c
e
pro
p
er
ti
es
o
f
th
e fi
lm
s
how
ed t
h
a
t
th
e
CdTe
thi
n
film
m
a
ter
i
a
l
s c
a
n be
used for fa
bri
c
a
tion of C
d
T
e
th
i
n
film
sola
r
ce
ll
.
Keyword:
B
a
nd
ga
p
Cd
s
CDTE Th
in Film
Solar cell
Copyright ©
201
6 Institut
e
o
f
Ad
vanced
Engin
eer
ing and S
c
i
e
nce.
All rights re
se
rve
d
.
Co
rresp
ond
i
ng
Autho
r
:
Ra
m
y
a K
Depa
rt
m
e
nt
of
El
ect
ri
cal
and
El
ect
roni
cs
E
n
gi
nee
r
i
n
g,
Sri Sai R
a
m
Coll
ege of
Eng
i
nee
r
i
n
g
,
B
a
ngal
o
re C
i
t
y
, I
n
di
a
Em
a
il: ra
m
y
aj
.k
14@g
m
ail.co
m
1.
INTRODUCTION
Power ge
neration by
sola
r e
n
ergy ca
n
act as
an alte
rn
ativ
e
so
urce
of en
erg
y
in th
e
fu
tu
re. Th
in-film
solar cells a
r
e
positione
d to becom
e
the fut
u
re
of solar
ene
r
gy
technol
ogy because of
t
h
eir less m
a
terial usa
g
e
and l
o
we
r cost
m
a
nufact
uri
ng
pr
ocesses
.
C
a
d
m
i
u
m
t
e
l
l
u
ri
de
(C
dTe
)
p
hot
o
vol
t
a
i
c
t
echn
o
l
ogy
has t
h
e p
o
t
e
nt
i
a
l
t
o
bec
o
m
e
a l
eadi
n
g e
n
er
gy
pr
o
duce
r
i
n
t
h
e com
i
ng deca
des i
n
s
o
l
a
r e
n
ergy
i
n
d
u
st
ry
.
The m
a
t
e
ri
al
can
be
use
d
as a
n
a
b
s
o
r
b
er
l
a
y
e
r f
o
r
sol
a
r cel
l
s
fo
r i
t
s hi
g
h
a
b
s
o
r
p
t
i
on c
o
-ef
f
i
c
i
e
n
t
and
o
p
t
i
m
u
m
ba
nd
ga
p
[
1
]
.
C
d
Te
has fa
voura
b
le physical cha
r
acteristics for
medical applica
tions that
have been i
n
vestigated in t
h
e re
port
e
d
pape
r [2]
.
The m
a
terial
is
consi
d
ere
d
to
be one of the
m
o
st
useful m
a
terial for the
f
a
bri
cat
i
o
n o
f
X-
ray
an
d
γ
-
ray detectors operating at room te
m
p
erature
due t
o
s
p
ecific properties of high av
e
r
a
g
e
at
om
i
c
num
ber, fi
ne
ch
arg
e
-t
ran
s
port prop
erties, hig
h
resistiv
ity an
d relativ
el
y
l
a
rge ba
nd
ga
p
ene
r
gy
[3]
.
T
h
e ob
ject
i
v
es
of
t
h
e
p
r
esen
t work
are d
e
po
sitio
n o
f
C
d
Te th
i
n
fil
m
o
n
Cd
S
(ch
e
m
i
cal b
a
th
d
e
po
sited
on
co
mmercial Flu
o
r
i
n
e-
d
o
p
e
d
tin
ox
ide (FTO) g
l
ass
su
bstrates wh
ich
will b
e
reported
later) and
ch
aracterize th
e Cd
Te/Cd
S
/FTO th
i
n
fil
m
s to
enrich
k
nowledg
e ab
ou
t fab
r
ication
of th
i
n
film
so
lar cell [4
].
2.
R
E
SEARC
H M
ETHOD
C
d
Te
fi
lm
was p
r
epa
r
e
d
on
C
d
S/
FT
O
gl
as
s su
bst
r
at
es at
hi
g
h
vac
uum
(~
1
0
-6
Torr)
b
y
th
e th
erm
a
l
ev
aporatio
n meth
od
.At th
e h
i
g
h
v
a
cuu
m
, th
e sub
s
trate
was
heate
d
with the hel
p
of ra
diant he
ater at a
c
e
rtai
n
te
m
p
eratu
r
e called
sub
s
trate t
e
m
p
eratu
r
e or
d
e
po
sition
te
mp
erat
u
r
e. In
the d
e
po
sition
of th
e th
i
n
film, th
e
substrate te
m
p
erature
was 250°C and annealing tem
p
erature was
100°C for
60 m
i
nutes
. The structural
an
alysis o
f
th
e fil
m
was p
e
rfo
r
m
e
d
u
s
ing
Ph
ilip
s X’p
e
rt PRO X-ray d
i
ffracto
m
eter [5
]. In
th
e ex
p
e
ri
men
t
,
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
6, No
. 2, A
p
ri
l
20
16
:
46
8 – 4
7
3
46
9
Cu
K
α
ra
di
at
i
o
n o
f
wave l
e
ng
t
h
,
λ
=
1.
54
1
7
8
Å wa
s use
d
a
nd t
h
e an
gl
e
of
di
ff
ract
i
o
n wa
s vari
e
d
f
r
om
20
° t
o
6
0
°.
Th
e grain size (D) of t
h
e film
was m
e
asu
r
ed
fro
m
Sch
e
rrer fo
rm
u
l
a written
b
e
l
o
w
u
s
ing
FWHM (
β
) o
f
t
h
e
(
1
11
) di
ff
ra
ct
i
on peak
[
6
]
.
cos
9
.
0
D
Here
,
θ
is
the
Bragg a
ngle.
T
h
e lattice para
meter
was calcu
lated
u
s
ing
t
h
e fo
llo
wi
n
g
equ
a
tio
n
whe
r
e
h
,
k
and
l
rep
r
esen
ts th
e Miller ind
i
ces an
d
d
is t
h
e
inter
plane
r
s
p
acing.
T
h
e
micro strai
n
(
ε
) a
n
d
di
sl
ocat
i
o
n den
s
i
t
y
(
)
o
f
t
h
e
f
i
lm
wasm
easur
ed
fr
om
t
h
e fol
l
owi
n
g e
q
uat
i
o
ns
[6]
.
2
2
1
4
cos
D
The s
u
rface image
of t
h
e
film was ta
ken usi
n
g Sca
nni
ng
E
l
ectron Micros
cope
(SEM
). T
h
e
optical
properties
lik
e tran
sm
itta
n
ce,
reflectan
ce, and
ab
sorp
tio
n
co-ef
f
icien
t
an
d
op
tical b
a
nd
g
a
p
were an
alysed
fro
m
UV
-VIS-
NIR
rec
o
r
d
i
n
g
spect
r
o
p
h
o
t
o
m
e
t
e
r (
s
hi
m
a
dju
,
U
V
0
3
1
0
0
,
Ja
p
a
n)
i
n
t
h
e
ph
ot
on
wave
l
e
n
g
t
h
ra
nge
f
r
o
m
400
t
o
2
500
n
m
.
Th
e ab
so
rp
tio
n
co-ef
f
icien
t
(
α
)
was m
easured
from
the followi
ng form
ula [7].
∝
t
Whe
r
e
t
is th
e
th
ick
n
e
ss o
f
the fil
m
s
an
d
T
is th
e tran
sm
i
tta
n
ce o
f
th
e films. Th
e op
tical
b
a
nd
g
a
p
en
ergy (Eg)
o
f
Cd
Te was esti
m
a
ted
u
s
ing
th
e fo
llowing
relatio
n
(
α
h
ν
)
2
= (h
ν
–E
g)
3.
AN
ALY
S
IS
O
F
CdTe/
C
dS/
FTO THI
N
F
L
IM
3.
1. Stru
ctur
al
Stud
y of Cd
Te/CdS/FTO Thin
Film
X-
ray
di
f
fract
i
on
(XR
D
)
pat
t
e
rns
of C
d
Te t
h
i
n
fi
l
m
st
udy
of
di
ffe
re
nt
su
bst
r
at
es a
nd t
h
i
c
kness a
r
e
sho
w
n i
n
fi
g
u
r
e
1. T
h
e
pea
k
s
at
2
θ
=2
3.
8
3
°,
26
.6
9°
, 3
0
.
3
1°
,
35
.4
0°
,
39
.3
9°
, 4
6
.
5
0
°
,
5
0
.
7
0
°
, 5
7
.
0
2° a
n
d 6
2
.
5
9
°
are f
o
u
n
d
in fi
gu
re 1
(
a)
. The
s
e peak
s co
rre
spo
n
d
s to
refle
c
tion f
r
om
(11
1
)
,
(
2
0
0
)
,
(
1
0
1
)
, (
2
20
), (
3
11
),
(1
12
)
,
(400) and (331) pla
n
es CdT
e
cubic struct
ure, res
p
ectiv
el
y
.
The fi
g
u
re
1(
b) a
nd fi
gu
r
e
1(c) s
h
o
w
e
d
C
d
Te
cubic structure
.
The
res
u
lts of the stru
ctural p
a
ram
e
ters o
f
Cd
Te th
in
films h
a
ve also
b
e
en
tabu
lated
in tab
l
e
1. T
h
e
dat
a
p
r
esent
e
d i
n
t
a
bl
e 1 (C
dTe/
C
d
S 1
0
0
0
nm
and C
d
Te/
C
dS
1
3
0
0
nm
) are c
o
m
p
arabl
e
wi
t
h
t
h
e
earlier re
p
o
rts
in ta
ble 1
(
Cd
Te
1
0
0
0
nm
).
All pea
k
s
refl
ected
in th
e XR
D
p
a
ttern
s are in
g
ood
ag
reem
en
t wit
h
ot
he
r re
po
rt
ed
pape
r [
8
]
as well. Th
e ob
served
d
v
a
lues in
figu
re
1
are
well
m
a
tch
e
s with
stand
a
rd
d
valu
es
[9
]. The figu
re-1
sh
owed
th
at th
e fil
m
Cd
Te/Cd
S
1
000
n
m
is
m
o
re crysta
llin
e th
an
Cd
Te 1
0
0
0
n
m
th
in
film
.
I
n
f
i
gur
e-1
,
the f
ilm
Cd
Te/C
d
S
10
00 n
m
sh
ow
ed
m
o
r
e
ref
l
ectio
n
p
e
ak
s th
an CdTe/CdS 130
0
n
m
th
i
n
f
i
l
m
.
Th
e C
d
Te/Cd
S
10
00
n
m
sa
m
p
les r
e
lativ
e in
ten
s
ity r
a
tio
o
f
(1
11)
,
(
220
)
,
(31
1
)
(
400
)
and
(3
31)
p
l
an
es ar
e 10
0,
57
.0
9,
2
8
.
4
4
,
2.
66 a
n
d 4
.
4
5
and t
h
e val
u
es
are com
p
arab
l
e
t
o
t
h
e st
and
a
rd
val
u
e
of
1
0
0
,
6
2
,
2
8
, 5
and
9
r
e
sp
ectiv
ely.
No
d
i
f
f
r
actio
n
peak
cor
r
e
spond
ing
to
m
e
tall
i
c
Cd
, Te,
or
o
t
h
e
r
co
m
p
o
unds w
a
s
o
b
s
erv
e
d
.
Th
e
XRD an
alysis rev
ealed
th
at t
h
e all fil
m
s are p
o
l
ycrysta
lline in
n
a
t
u
re and crystalin
ity is
i
m
p
r
ov
ed. Th
e lattic
e
p
a
ram
e
ter was calcu
lated
to
b
e
6
.
4
8
2
Å
which
is v
e
ry close to
th
e standard
v
a
lue of
6
.
4
81Å. Th
e cal
cu
lated
v
a
lu
es ag
ree
well with
th
at o
f
repo
rted
v
a
l
u
es [10
]
. The c
a
lculated ave
r
a
g
e grain size
was about 23-48
nm
.
This was in close agreem
ent
with
th
at o
f
CdTe fil
m
s wh
ere a s
m
a
lle
r average grai
n size (24
nm
) was reported
[1
1]
. The l
a
r
g
e
r
grai
n si
ze i
s
an im
port
a
nt
fact
or to increase
photovolta
ic efficiency.
Where,
h
ν
is th
e in
cid
e
n
t
ph
ot
o
n
e
n
er
gy
. The t
h
i
c
kne
s
s
of t
h
e
fi
l
m
was m
easur
ed b
y
in
situ
FTM
5
qu
artz crystal th
ick
n
e
ss m
o
n
itor
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
ECE
I
S
SN
:
208
8-8
7
0
8
Vi
sual
a
n
d
S
u
r
f
ace Pr
ope
rt
i
e
s of
C
d
Te
Thi
n
Fi
l
m
s o
n
C
d
S/
FTO
Gl
a
ss
Su
bst
r
at
es
(Ra
m
ya
K)
47
0
(Edward
s
,
UK).
If d
e
n
s
ity of th
e m
a
terial is kno
wn
, th
e rate o
f
d
e
po
sitio
n,
wh
ich
is differen
t
for
d
i
fferen
t
ele
m
en
ts, can
b
e
co
n
t
ro
lled usin
g th
e m
o
n
ito
r [1
2
]
.
Fi
gu
re
1.
XR
D
spect
ra
o
f
(a)
C
d
Te
10
0
0
nm
(b
) C
d
Te/
C
d
S
1
0
0
0
nm
(c)
C
d
Te/
C
d
S
13
00
nm
Fig
u
re
2
.
SEM
i
m
ag
e of CdTe th
in
film
o
f
th
ickn
ess
1
0
0
0
nm
depo
si
t
e
d
o
n
C
d
S t
h
i
n
fi
l
m
wi
t
h
m
a
gni
f
i
cat
i
on
X
250
00
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
6, No
. 2, A
p
ri
l
20
16
:
46
8 – 4
7
3
47
1
3.
2.
Surf
a
ce
S
t
ud
y
of
C
d
T
e
/
C
dS/
FT
O
T
h
i
n
Fi
l
m
The s
u
rface
m
o
r
p
hol
ogy
of
C
d
Te t
h
i
n
fi
lm
de
po
si
t
e
d
on
a
gl
ass
su
bst
r
at
e
o
b
ser
v
e
d
un
de
r a sca
n
ni
n
g
electro
n
m
i
cro
s
cop
e
is sho
w
n
in
fi
g
u
re 2. Th
e crystallite
s o
f
th
ese films are reg
u
l
ar
ly
sp
iral sh
ap
ed
with
a
typ
i
cal size o
f
ab
ou
t
7
0
0
n
m
.
It is clear th
at
th
e layer is no
t un
ifo
r
m
an
d do
es
n
o
t
co
mp
letely co
v
e
r on
t
h
e
FTO s
u
bstrate. As res
o
l
u
tion (X
25000) increases a
ve
ry
few
pinholes are obse
rve
d
clearly in the film
.
In
di
vi
dual
grai
n
bo
u
nda
ry
i
s
not
s
p
eci
fi
cal
l
y
vi
si
bl
e rat
h
er
grai
ns a
r
e c
o
n
n
ect
ed t
o
one
a
not
her l
i
ke r
o
p
e
. Thi
s
su
bstrate ch
aracteristic is in
ag
r
eem
en
t with th
e
reported
work [13
]
. Th
e surface
im
age suggested that CdS
nucleates at these points a
n
d
grow as c
o
lumns
norm
al to
the s
ubst
r
ate. T
h
e
grains of the film
are enta
ngl
e
d
due t
o
dep
o
si
t
on t
o
p o
f
C
d
S/
FTO gl
ass s
u
b
s
t
r
at
e and f
o
r
m
ed wi
de gr
ai
n b
o
u
n
d
ari
e
s.
Thi
s
si
t
u
at
i
on
can be
chan
ge
d t
o
a c
e
rt
ai
n e
x
t
e
nt
b
y
usi
n
g ei
t
h
e
r
t
h
i
c
k C
d
S
o
r
C
d
Te l
a
y
e
rs
o
r
d
e
po
si
t
i
on
of
a
bu
ffe
r l
a
y
e
r.
Tabl
e 1.
Stru
ctural
param
e
ters o
f
Cd
Te thi
n
film
s
Sa
m
p
le
Na
m
e
Observed 2
(degree)
Observed
FWHM
(
2
)
Observed (d)
(n
m)
Standard
(d) (n
m)
Relative
intensity
Pla
n
e
(h
k
l
)
23.
833
8
0.
1378
0.
3734
0.
3742
100
(
111)
26.
687
1
0.
1574
0.
3340
0.
3355
22.
96
(
200)
30.
313
1
0.
4723
0.
2949
0.
2906
7.
52
(
002)
CdTe/CdS
1000 nm
35.
396
0
0.
2362
0.
2536
0.
2514
6.
09
(
101)
39.
384
0
0.
1968
0.
2288
0.
2290
57.
09
(
220)
46.
504
2
0.
2362
0.
1953
0.
1954
28.
44
(
311)
50.
703
1
0.
4723
0.
1801
0.
1812
4.
92
(
112)
57.
018
1
0.
9446
0.
1615
0.
1619
2.
66
(
400)
62.
587
7
0.
5760
0.
1483
0.
1488
4.
45
(
331)
C
d
Te 1
0
00
nm
[1
]
23.
852
5
0.
1771
0.
3731
0.
3742
100
(
111)
39.
335
3
0.
2165
0.
2291
0.
2290
23.
33
(
220)
46.
482
7
0.
3840
0.
1952
0.
1954
13.
38
(
311)
CdTe/CdS
1300 nm
23.
819
0.
0984
3.
735
0.
3742
100
(
111)
39.
351
0.
2362
2.
290
0.
2290
44.
98
(
220)
46.
488
0.
2755
1.
953
0.
1954
24.
08
(
311)
56.
857
0.
4723
1.
619
0.
1619
2.
89
(
400)
62.
403
0.
3840
1.
487
0.
1488
6.
47
(
331)
3.
3.
Optic
a
l Stud
y of CdTe
/CdS/FTO Thin Fil
m
Fig
u
re
3
sh
ows th
e v
a
riatio
n
o
f
tran
sm
ittan
c
e o
f
C
d
Te t
h
in fil
m
o
f
th
ickness 10
00
n
m
d
e
p
o
sited
on
Ch
em
ica
l
Bath
D
e
p
o
s
ited
-
C
d
S w
ith pho
ton
w
a
v
e
len
g
t
h
v
a
ryin
g
in th
e
r
a
ng
e
b
e
tw
een
3
0
0
n
m
an
d
1
500 n
m
.
Fig
u
re
3
.
Tran
smit
tan
ce v
a
riatio
n
of CdTe th
i
n
fil
m
s with
wav
e
leng
th
0
10
20
30
40
50
300
600
900
1200
1500
1800
T
r
ansmittance (T%
)
W
ave length (nm)
C
d
Te/
C
dS 1300
nm
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
ECE
I
S
SN
:
208
8-8
7
0
8
Vi
sual
a
n
d
S
u
r
f
ace Pr
ope
rt
i
e
s of
C
d
Te
Thi
n
Fi
l
m
s o
n
C
d
S/
FTO
Gl
a
ss
Su
bst
r
at
es
(Ra
m
ya
K)
47
2
Fi
gu
re
4.
R
e
fl
e
c
t
a
nce v
a
ri
at
i
o
n
of
C
d
Te
t
h
i
n
fi
lm
s
Fig
u
re
5
.
Ab
sorp
tion
co
efficien
t v
a
riatio
n of
Cd
Te th
i
n
fil
m
s
Figure
6. (
α
h
ν
)
2
vs ph
ot
on
ene
r
gy
(
h
ν
)
p
l
o
t
o
f
Cd
S/C
d
Te th
in film
s
The fi
gure s
h
owed c
o
nsistent
optical trans
p
arency
i
n
t
h
e s
p
ect
ral
re
gi
o
n
bet
w
ee
n 1
2
00
nm
t
o
150
0
nm
. Hi
gh t
r
ans
m
i
t
t
a
nce i
n
a hi
ghe
r wa
vel
e
n
g
t
h
re
gi
o
n
an
d
a sharp a
b
s
o
r
p
t
i
on e
dge i
s
o
b
ser
v
e
d
i
n
t
h
e fi
lm
s.
The a
b
s
o
r
p
t
i
o
n e
dge i
s
i
n
t
e
rrel
a
t
e
d t
o
t
h
e
opt
i
cal
ba
nd
ga
p
whi
c
h
agree
s
wi
t
h
rep
o
rt
e
d
wo
rk
. The
tran
sm
it
tan
ce falls
steep
ly with
d
ecreasi
n
g
wav
e
len
g
t
h
fr
om
900
nm
t
o
ab
o
u
t
8
0
0
nm
. The
decr
ease i
n
transm
ission coul
d arise due to the in
crease
in absorba
n
ce
asso
ciated with cha
nge in
s
u
rface m
i
crostructure
as
re
po
rt
ed by
C
h
an
d
r
am
ohanet
.
Fi
gu
re 4
s
h
o
w
s
t
h
e vari
a
t
i
on of refl
ect
a
n
ce wi
t
h
ph
ot
o
n
wavel
e
ngt
h
i
n
t
h
e
0
5
10
15
20
25
30
35
40
300
800
1300
1800
2300
Reflectance (%
)
W
ave length (nm)
C
d
Te/
C
dS 1000
…
0.7
1.7
2.7
3.7
4.7
5.7
6.7
7.7
300
600
900
1200
1500
1800
Absorption coefficient,
α
(cm
-1
) x
10
4
Wav
e
length
(nm)
C
d
Te/
C
dS 1000
nm
0
10
20
30
40
50
0.5
1
1.5
2
2.5
3
3.5
(
α
h
γ
)
2
x 10
9
Wav
e
length
(nm)
CdTe/CdS 1000
nm
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
6, No
. 2, A
p
ri
l
20
16
:
46
8 – 4
7
3
47
3
r
a
ng
e 300
n
m
t
o
15
00n
m
.
Fr
om f
i
g
u
r
e 4, it i
s
o
b
s
er
ved
th
at
reflectance fal
l
s with decreas
ing wa
velengt
h
(300-
88
0
nm
). The
vari
at
i
o
n o
f
a
b
sor
p
t
i
o
n co
-ef
f
i
ci
ent
(
α
) wi
t
h
wavel
e
ngt
h i
n
t
h
e ra
nge
vary
i
ng
bet
w
ee
n
30
0nm
-
15
0
0nm
of C
d
Te t
h
i
n
fi
l
m
s is sh
o
w
n i
n
fi
g
u
re
5.
F
r
om
fig
u
re
5
,
it is seen
th
at i
n
th
e sh
orter
wav
e
leng
th
t
h
e
abs
o
r
p
t
i
on c
o
-
e
ffi
ci
ent
e
xhi
b
i
t
s
hi
ghe
r
val
u
es, t
h
ese
val
u
e
s
of
(
α
>10
4
)
mean
s th
ere is a larg
e
p
r
ob
ab
ility o
f
th
e allo
wed
d
i
rect tran
sitio
n
wh
ich
agrees
with
th
e wo
rk
o
f
Mo
ttet. Al [1
3
]
.
Valu
e of ab
sorp
tio
n
co
-efficien
t
decrease
s
steeply with incre
a
se in wavele
ngt
h and
rem
a
in
s con
s
istent at h
i
g
h
e
r
wav
e
leng
th
. The lo
w
ab
so
rp
tio
n co-efficien
t m
a
k
e
s Cd
Te film
s
u
s
efu
l
fo
r
op
tical co
m
p
o
n
en
ts in h
i
g
h
laser wi
n
dow and
m
u
l
tisp
ectral ap
p
lication
s
,
pro
v
i
d
i
ng
g
ood
i
m
ag
in
g
ch
aracteristic.
In fi
gu
re 6, (
α
h
ν
) ² i
s
pl
ot
t
e
d
agai
nst
ph
ot
o
n
ener
gy
(
h
ν
) t
o
fi
n
d
t
h
e ba
n
d
ga
p ener
gy
of C
d
Te t
h
i
n
fi
lm
.The l
i
n
ear depe
n
d
e
n
ce sho
w
e
d
by
(
α
h
ν
)² wi
t
h
p
h
o
t
on e
n
er
gy
(h
ν
) in
d
i
cates th
at th
e tran
smis
sio
n
is
di
rect
. The
di
r
ect
band
gap e
n
er
gi
es o
f
th
e fil
m
s are d
e
termin
ed
b
y
ex
trap
o
l
ating
th
e straig
h
t
po
rtion to
th
e
ener
gy
axi
s
. B
a
nd
gap i
s
f
o
u
nd
1.
53
±
0
.
1
eV
by
ext
r
ap
ol
at
i
on
of
dat
a
poi
nt
whi
c
h i
s
ve
ry
cl
ose t
o
st
anda
r
d
val
u
e
of
1
.
5e
V
.
A
b
s
o
r
p
t
i
o
n c
o
ef
fi
ci
ent
i
s
us
ed t
o
desc
ri
be
t
h
e re
duct
i
o
n i
n
i
n
t
e
nsi
t
y
of l
i
ght
i
n
a
m
e
di
um
as a
fu
nct
i
o
n o
f
di
st
ance. T
h
e e
n
er
gy
ga
p i
n
a se
m
i
cond
uct
o
r i
s
resp
o
n
si
bl
e f
o
r t
h
e f
u
ndam
e
n
t
al
opt
i
cal
abso
rpt
i
o
n
edge
. The
fundam
ental absorption pro
cess
is one in
whic
h a phot
on is
abs
o
rbed a
n
d an electron is excited
fr
om
an occ
u
pi
ed
val
e
nce
ba
n
d
st
at
e t
o
a
n
u
n
o
ccu
pi
ed
c
o
n
d
u
ct
i
o
n
ban
d
st
at
e, i
f
p
hot
on
en
ergy
i
s
l
e
ss t
h
a
n
t
h
e
g
a
p
en
erg
y
, t
h
en
th
e electron will n
o
t
b
e
abso
rb
ed
. Su
ch
i
n
ter
b
a
nd
ab
sorp
tion
p
r
o
cess
is p
o
s
sib
l
e on
l
y
if th
e
ph
ot
o
n
e
n
e
r
gy
i
s
hi
g
h
er
t
h
a
n
t
h
e
ban
d
ga
p e
n
ergy
.
4.
CO
NCL
USI
O
NS
Cd
Te th
in
film was su
ccessfu
lly d
e
po
sited
on
Cd
S/FTO sub
s
trate u
s
ing
th
erm
a
l
ev
apo
r
at
i
on
m
e
thod. T
h
e st
ruct
ural study of the
fi
lm
showed that the
film
is
polycryst
alline in nature and crystalinity is
i
m
p
r
ov
ed
du
e
to
Cd
S/FTO layer. Th
e surface i
m
ag
e o
f
th
e fil
m
co
n
c
luded
th
at th
e ch
arg
e
carrier m
o
b
ilities
al
on
g t
h
e
s
e c
o
l
u
m
n
ar t
y
pe m
a
t
e
ri
al
s have
hi
ghe
st
p
o
ssi
bl
e
val
u
es
an
d t
h
e
grai
n
bo
u
nda
ry
scat
t
e
ri
ng
bec
o
m
e
s
m
i
nim
a
l duri
n
g PV act
i
v
i
t
y
across t
h
e
devi
c
e
st
ruct
ur
e. Th
e fi
lm
s showed
42% t
r
a
n
spa
r
e
n
cy
, 3
2
% refl
e
c
t
a
nc
e
and
hi
g
h
abs
o
r
p
t
i
on c
o
-e
ffi
ci
ent
(
α
>10
4
)
.
The o
p
t
i
cal
ban
d
ga
p of t
h
e fi
l
m
was fou
nd
1
.
5
3
eV. Th
ese
r
e
su
lt
re
veale
d
t
h
at
CdTe lay
e
r c
o
uld
be
s
u
ita
ble as
abs
o
rber layer for
Cd
Te/C
dS heteroj
u
n
c
ti
on
solar cell
struct
ure
.
REFERE
NC
ES
[1]
K.M.A. Hussain, Z.H. Mahm
ood, Ishtiaqu
e M
S
y
ed
, T.Begum, T. Faru
q
e
,
an
d J. Parvin, “Thermal vacuum
deposition
of
ca
dm
ium
tellurid
e
thin f
ilm
s solar
c
e
ll
m
a
teri
al
”.
[2]
A.
M.
D.
Ede,
E.J.
Morton,
P.
D
e
Antonis,
Thin film Cd
Te for
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appli
cations. N
u
clear Instruments
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in
Ph
y
s
ics Res
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[3]
Katland
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a
tres-E
strada, G.
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p
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s to Use CdTe
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a
l of
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ysics Conferen
ce
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p
p
523-526.
[4]
Lovergin
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F. an
d Mancin
, A. I.
(2005),
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y
d
rog
e
n Tr
ansport Vapor Growth an
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ick CdTe
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ers fo
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pplications”, Cr
y
s
t R
e
s Tech. Vol. 40
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.
[5]
K.
M.
A.
Hussain,
T.
Faruqe, J.
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S Ahmed,
Z.
H.
Mahmoo
d & Ishtiaqu
e
M. S
y
ed
, “Study
of CdTe Nuclear
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i
al In Thin Film Form Using Thermal
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ation Method, M
a
lay
s
ia
n Journal of Medical
an
d
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No. 3
(20
15).
[6]
K.M.A. Hussain, T. Begum, Z.
H. Mahmood, Ishti
a
que M. S
y
ed
, S. Ahmed,
“Study
of thermally
deposited CdS thin
films for CdTe thin film solar cell
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n
ternationa
l Journal of Nanoscience and Nanoen
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