International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 3, Issue 9, September 2014
ISSN 2319 – 4847
Structural and Optical Properties of Mn-Doped
Tin Oxide Thin Films
1
Hamid S.Al-Jumali , 2Ahmad Z.Al-Jenaby
1
Prof. Dr.Department of physics,College of Education for pure Science, University of Anbar,Iraq
2
Master.Department of physics, College of Education for pure Science, University of Anbar, Iraq
ABSTRACT
The present paper discusses the optical and structural properties of Mn-doped tin oxide thin film prepared on glass substrate by the
spray pyrolysis technique at a temperature of 400 ̊C. Optical characteristics were studied by UV/VIS Spectrophotometer at (3001100 nm) and observed that the transmission value was more than 75 % at the visible wavelength range. X-ray diffraction study
shows that the film was tetragonal rutile structure of SnO2. Morphology analysis studied by atomic force microscopy (AFM) and
reveals that the grain size of the prepared thin film is approximately (82.12-111.62)nm , with a surface roughness of (2.79 - 3.87)
nm as well as root mean square of (3.39 -4.78 )nm for SnO2(pure)and Mn-doping. The direct energy gap (Eg) ranged between
(3.22-1.95) eV, is measured by UV/VIS.
Keywords:Structural and Optical properties, Thin Film, SnO2: Mn.
1. ІNTRODUCTION
The study and application of thin film technology is entirely entered in to almost all the branches of science and
technology. Present study which describes the synthesis and study of optical and structural characteristics of manganese
doped tin oxide (SnO2) is really more interesting for researchers due to its vast applications. Due to the properties like
reflectivity, transparency, low electrical sheet resistance etc., tin oxide thin films has immense applications such as gas
sensing material for photovoltaic cell in transistors, transparent conductive electrode for solar cell sphotochemical and
photoconductive devices in liquid crystal display [1] gas sensor devices[2,3]. Till today so many methods were adopted to
synthesize doped or un-doped tin oxide films such as R.F. Magnetron Co- sputtering, ThermalEvaporation, and Chemical
Vapor Deposition, Laser Pulse Evaporation, Sol-Gel, Spray Pyrolysis and ultrasonic spray pyrolysis [4, 5, and 6]. Tin
oxide crystallizes tetragonal rutilestructure [7, 8] with unit cell parameters a=b= 4.737A and c= 3.186 A . It is an ntype semiconductor having high band gap energy (≈ 3.6 eV) [9, 10] with high chemical and mechanical stabilities [11] and
is more transparent in the region of visible spectrum due to high band gap, having high electrical conductivity due to free
electrons in oxygen vacancy holes] 12, 13].
2. EXPERIMENTAІ
A SnO2 (Pure) and Mn doped thin films atdifferent concentration (3, 5 and 7 wt%) of Manganese ,were prepared by
chemical spray pyrolysis. The films deposited onto micro-glass slides were first cleaned with detergent water and then
dipped in acetone .Spray solution was prepared by mixing 0.1 M aqueous solutions of SnO2,and MnCl2 at ratio (3 ,5 and
7 wt %) using a magnetic stirrer . The automated spray solution was then transferred to the hot substrate kept at the
normalized deposition temperature of 673 K using filtered air as carrier gas at a flow rate normalized to
approximately(1.8) ml/min . To prevent the substrate from excessively cooling, the prepared solution was sprayed on the
substrate for 10 s with 15 s intervals .The films had a uniform thickness of range (390-410)nm .The structural properties
were determined by X-ray diffraction (XRD; Shimadzu) with CuKα radiation ( λ = 0.15406 nm). Film morphology was
analyzed by atomic force microscope (AFM)-type (CSPM).The optical absorption and transmission spectra were obtained
using a UV-VIS spectrophotometer 6800JENWAY, Germany) within the wavelength range of (300-1100) nm.
Volume 3, Issue 9, September 2014
Page 139
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 3, Issue 9, September 2014
ISSN 2319 – 4847
3. RESULTS AND DISCUSSION
The structure of the prepared tin oxide thin films were investigated by XRD. Figure (1) shows the graph between (2Ө)
versus diffracted ray intensity. the major diffraction peaks at 2Ө = (34.4) ,(26.10),(38.2 ), and (51.3 ) for SnO2(pure) and
SnO2: Mn 3,5 and 7 wt % ,respectively. Thus, the experimental results proved that the polycrystalline nature of the
prepared samples as depicted in Figure (1). The result corresponds with that described byIssam et al [14].Moreover, an
increase in the main peak intensity is observed in the presence of Manganese. A comparison with ASTM card 41-1445,
reveals that the tin oxide thin film exhibits a crystal structure tetragonal type with a preferred orientation (101) and other
planes, i.e., (110 ), (200 ), and (211 ) for 2Ө = (26.10 ), (38.20), and (51.30 ). This result agrees with that reported
byK.Vadivel et al [13]. The crystalline size (D) is determianed from main pack at 2Ө= (34.40) and found to be equal to
(41-52) nm. Table (1) passed on Scherer formula [13].
Figure1. X-ray diffraction patterns of SnO2, SnO2: Mn thin films
Table 1:Average Crystallitesize,d (101) and FWHM forMn doped tin dioxide in comparison with
undoped tin dioxide
Doping
ratio
SnO2
Pure
Average
Crystallit
e sizes
from XRD
(nm)
52
FWHM
( β)
2.66547
0.1722
0
SnO2:M
n 3wt %
52
SnO2:M
n 5wt %
50
SnO2:M
n 7wt %
41
Volume 3, Issue 9, September 2014
d(101)(Å
)
2.61384
0.1832
0
2.63420
0.1911
0
2.65508
0.1981
0
Page 140
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 3, Issue 9, September 2014
ISSN 2319 – 4847
Figure (2) displays AFM image of the films at (pure, 3, 5, and 7 wt %) on glass. It shows the presence of homogenous
grains throughout the film. The grain size of this film is (82.12-111.62) nm for the described different concentration.
The grain size, Root mean square (RMS) and roughness of these films are shown in table 2. The root main square and
roughness (R) are equal to (3.39, 2.24, 3.11 and 4.78) nm, (2.79, 1.85, 2.59 and 3.87) nm respectively. Therefore, the
film roughness decreases with decreases of grain size.
Figure2 The atomic force microscope (a) 2-D and (b) 3-D Image 0f prepared films
Volume 3, Issue 9, September 2014
Page 141
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 3, Issue 9, September 2014
ISSN 2319 – 4847
Table 2: The Average Crystallite sizes and Roughness average for undoped and doped SnO2 films
Doping
ratio
SnO2
Pure
SnO2
:Mn
(3
wt.%)
SnO2
:Mn
(5
wt.%)
SnO2
:Mn
(7
wt.%)
Average
gain sizes
from AFM
(nm)
Root mean
square(nm)
Roughness
Average
(nm)
111.19
3.39
2.79
94.30
2.24
1.85
82.12
3.11
2.59
111.62
4.78
3.87
Figure (3) observes the absorption (A), transmission (T), and energy gab (E_g) which have been obtained by uv/vis
from (300-1100) nm. Figure (3) shows the absorption edge for pure SnO2 starts with (390) nm reveals that the
nanocrystalline effect of the films. Alsoabsorptionedge ofMn doping tin oxide films shift toward the low energy (Blue
shift). The experimental result agrees with that reported by K.Vadivel and Ana-Maria et al [13, 15]. The optical
transmittance of Mn-doped SnO2 thin films in thevisible region is depicted in Figure (4). It can be noticed that when
the film is SnO2 (pure), the transmittance is about 77% whereas transmittance decreases to 73% at Mn-doped 3%.
Nevertheless, increasing the concentration of doping of Mn-doped (5 and 7%) decreases the transmittance about (67%,
60%) respectively. Decreasing of the transmittance after doping is owing to increment absorption coefficient of films.
Figure 3. The absorption of prepared filmsFigure4The transmittance of prepared films
The optical band gap of SnO2 and SnO2: Mn films is shown in Figure (5) andwere compared with the band gap value
for undoped tin dioxide, calculated through the same method (Table 2), from the plot of (αhv)2 as afunction of photon
energy (hʋ ) according ot the Tauc,s formula for direct band gap semiconductors [16,17]
(hα)2= β(hʋ -Eg)
(1)
Where α is the absorption coefficient, β is a constant, Egis the optical energy gap, ʋ is the incident photon frequency,
and h is Planck, s constant.
Volume 3, Issue 9, September 2014
Page 142
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 3, Issue 9, September 2014
ISSN 2319 – 4847
Figure 5Band gap (Eg) of prepared films.
Table 2: Band gap energies calculated with Tauc method
Doping ratio
SnO2:pure
SnO2:Mn 3wt. %
SnO2:Mn 5wt. %
SnO2:Mn 7wt. %
Eg (ev)
3.22
3.05
2.96
1.95
It is evident from the mentioned figure that the energy gap of SnO2 (pure) is equal to (3.22) eV while the doping has
been used, the energy gap decreases with increasing of Mn concentration. As a matter of fact, the energy gap is found
to be 3.05eV at 0.03 Mn concentration. That is more clear that when Mn-doped is increased to 5 and 7wt. %, the
energy gap is decreased to (2.96 and 1.95) eV, respectively. This can be attributed to the fact that the energy gap of Mn
oxide is less than the energy gap of tin oxide. Finally, the results correspond with of Jochan and Ana-Maria et al. [15,
18].
4. CONCLUSIONS
Manganese doped tin oxide thin films were prepared by spray pyrolysis method. The X-ray diffraction shows the
polycrystalline nature of as deposited films with tetragonal structure. The crystalline size of the film was calculated
using Debye-Scherer formula is varies from 41-52 nm corresponds to four strong peaks. The AFM images show
homogenous grain films with grain sizes ranging from (82.12) nm to (111.62) nm.UV-VIS spectra obtained for all four
samples are characteristic to tin dioxide. The calculated band gap energies decrease with the increase of dopant
concentration, as a result of the occurrence of additional energetic levels in the forbidden band.
REFERENCES
[1] S.K. Tripathy, B. Nagarjun, V. Siva Jahnavy,"Optical andStructural characteristics ofCopper doped Tin oxide thin
fill prepared by thermal evaporation method" InternationalJournal of Engineering and Innovative Technology
(IJEIT), July 2013, p.p 296-300.
[2] Manal M. Abdullah, Mahdi H. Suhail and Sabah I. Abbas,"Fabrication and Testing of SnO2 Thin Films as a Gas
Sensor" Archives of Applied Science Research, 2012, 4 (3):1279-1288.
[3] Chengxiang Wang, Longwei Yin, Luyuan Zhang, Dong Xiang and RuiGao," Metal OxideGas Sensors: Sensitivity
and Influencing Factors"Sensors 2010, 10, 2088-2106.
[4] G. E.Patil, D. D.Kajale, D. N.Chavan, N, K.Pawar, P. T.Ahire, S. D.Shinde,V.B.Gaikwad and G. H. Jain,
"Synthesis, characterization and gas sensing performance of SnO2thin films prepared by spray pyrolysis" Bull.
Mater. Sci., Vol. 34, No. 1, February 2011, pp.1-9.
[5] Tripti Shukla "Synthesis of Tin Oxide Thick Film and Its Investigation as a LPG Sensor at Room Temperature"
Journal of Sensor Technology, 2012, 2, 102-108.
[6] Talaat M. Hammad, Naser K. Hejazy Structural, "Electrical and Optical Properties of ATOThin Films Fabricated
by Dip Coating Method" Int. Nano Lett., Vol. 1, No. 2, July 2011, pp. 123-128.
Volume 3, Issue 9, September 2014
Page 143
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 3, Issue 9, September 2014
ISSN 2319 – 4847
[7] H.Pirmoradi, J.Malakootikhah, M.Karimipour, A.Ahadpour, N.ShahtahmTripti Shuklaasebi and F.EkhtiaryKoshky,
"Study of Cobalt-Doped SnO2 Thin Films" Middle -East Journal of Scientific Research 8(1), 2011, p.p 253-256.
[8] A. R.Babar, S. S. Shinde, A. V. Mohlkar, C. H. Bhosale, J. H.Kim, and K. Y.Rajpure,"Physical properties of
sprayed antimony doped tin oxide thin films: The role of thickness," Journal of semiconductors, vol. 32, No. 5,
2011, 053001(8pp).
[9] Saturi Baco1, Abdullah Chik, Fouziah Md. Yassin, Study on Optical Properties of Tin Oxide Thin Film at Different
Annealing Temperature" Journal of Science and Technology, 2012, pp. 61-72.
[10]F.R.Chowdhury,S.Chowdhury,F.Hasan and T.Begum,"Optical properties of undoped andindium-doped Tin
oxideThinFilms"Journal of Bangladesh Academy of Sciences, Vol. 35, No. 1, 2011, 99-111.
[11] H. Salehi, M. Aryadoust and M. Farbod, "Electronic and Structural Properties ofTinDioxidein Cubic Phase"
Iranian Journal of Science & Technology, Transaction A,Printed in the Islamic Republic of Iran, 2010, Vol.34, No.
A2.
[12] S.K.Tripathy, B. P. Hota, "Influence of Substrates Nature on Optical and StructuralCharacteristics of SnO2 Thin
Film Prepared by Sol-Gel Technique," Journal of Nano-and Electronic Physics 2013, No.3 ,03012 (5pp).
[13] K. Vadivel, V. Arivazhagan, S. Rajesh, "Mn doped SnO2 Semiconducting Thin Films Prepared by Spray Pyrolysis
Method," International Journal of Scientific & EngineeringResearch Volume 2, Issue 4, April-201, ISSN 22295518.
[14] Issam M. Ibrahim, Ifikhar M. Ali, Raab M. Al-Haddad, Huda Dr. Muhammed, "Influence of substrate temperature
on structural and optical properties of SnO2 films, "Iraqi Journal of physics ,vol.10,No.18,2012. p.p. 50-55.
[15] Ana-Maria Ungureanu, IoanaJitaru, FlorinelaGosnea, "Mn Doped SnO2 Preparedbya Sol-Gel Method," U.P.B.
Sci. Bull., Series B, Vol. 75, Iss. 3, 2013, ISSN 1454-2331.
[16] Hamid S. Al-Jumaili, Abubaker. S. Mohammed, " Structural and Optical Properties of Cu2Zn1-x CdxSnS4 Thin
Film asa an Absorber Material for Solar Cell," International Journal of Emerging Technology and Advanced
Engineering,vol.3 Issue 9 September 2013,p.p. 39-43.
[17] Sabri. J. Mohammed, Thair. KH. Salih, “A Study of structural and visual features of SnO2 membrane to be
prepared Through Evaporation in Space," Jou. Tikrit, Iraq ISSN: 1813-1662, 2013, (5)18 pp.231-235.
[18] Jochan Joseph, Varghese Mathew, and K. E. Abraham, "Studies on Cu, Fe, and Mn Doped SnO2 SemiConducting Transparent Films Prepared by a Vapour Deposition Technique," CHINESE JOURNAL OF PHYSICS
VOL. 45, NO. 1 FEBRUARY 2007pp.84-97.
Volume 3, Issue 9, September 2014
Page 144