SnO2 nanostructures thin films with thickness of 500 nm were prepared by electron beam-physical vapor deposition on glass substrate at temperature of 300, 373, 443, and 583 K. Structural and morphological properties of these nanostructured thin films were studied by Scanning and Transmission Electron Microscopy (SEM, TEM) and Atomic Force Microscope (AFM) methods. The changes in structural and morphological properties are found at different temperatures. Increase temperature causes important change of the structural and morphological properties. The sample prepared at 300 K has crystalline structure and the sample prepared at 583 K has amorphous structure. Roughness parameters have low values at 300, 373, 443 K as opposed to the values obtained at 583 K. This different behavior may be due to the amorphous structure of the sample that was observed in the TEM analysis

B. BITA

C. GHEORGHIES

D. C. VLADU

I. STOICA

M. BERCEA

M. BORDEI

M. C. POPESCU

The Annals of “Dunarea de Jos” University of Galati Fascicle IX Metallurgy and Materials Science

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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 3 – 2013, ISSN 1453 – 083X 
 
 
 
 
INFLUENCE OF SUBSTRATE TEMPERATURE ON STRUCTURAL 
AND MORPHOLOGICAL PROPERTIES OF SnO2 
NANOSTRUCTURED THIN FILMS 
 
D.C. VLADU1, C. GHEORGHIES1, M. BERCEA2, I. STOICA3,  
M.C. POPESCU4, B. BITA4, M. BORDEI5 
1Faculty of Sciences and Environment, Chemistry, Physics and Environment Department,  
„Dunarea de Jos” University of Galati, Romania 
2U. T. Gh. Asachi Iasi, Romania 
3"Petru Poni" Institute of Macromolecular Chemistry Polymer Materials Physics-Atomic Force Microscopy, 
Aleea Grigore Ghica Voda, 41A, Iasi - 700487, Romania 
4National Institute for Research and Development in Microtechnologies IMT  
126 A, Erou Iancu Nicolae Street, 077190 Bucharest, Romania 
5Faculty of Materials Science and Environment,“Dunărea de Jos” University of Galaţi,  
111, Domnească Street, 800201, Galaţi, Romania 
email: cvladu2010@gmail.com 
 
ABSTRACT 
 
SnO2 nanostructures thin films with thickness of 500 nm were prepared by 
electron beam-physical vapor deposition on glass substrate at temperature of 300, 
373, 443, and 583 K. Structural and morphological properties of these 
nanostructured thin films were studied by Scanning and Transmission Electron 
Microscopy (SEM, TEM) and Atomic Force Microscope (AFM) methods. The 
changes in structural and morphological properties are found at different 
temperatures. Increase temperature causes important change of the structural and 
morphological properties. The sample prepared at 300 K has crystalline structure 
and the sample prepared at 583 K has amorphous structure. Roughness parameters 
have low values at 300, 373, 443 K as opposed to the values obtained at 583 K. This 
different behavior may be due to the amorphous structure of the sample that was 
observed in the TEM analysis. 
 
KEYWORDS: electron beam-physical vapor deposition, structural, 
morphological properties, TEM, SEM, AFM 
 
1. Introduction 
 
Nanostructures of SnO2 thin films have been 
employed in a wide range of applications including 
solid state gas sensors, liquid crystal displays, 
transparent conducting electrodes, infrared reflectors, 
plasma display panels (PDPs), transistors, etc. [1–5]. 
Among such semiconductors, SnO2 
nanostructured thin films seem to be a good candidate 
for the solar cell applications (e.g., as a window 
material) because of there wide band gap (3.6 eV) at 
room temperature [6–10]. In addition, SnO2 is useful 
as a hard film material for applications requiring high 
refractive and reflective properties. SnO2 thin films 
have been prepared by various techniques such as 
RF-magnetron sputtering [1, 11, 12], electron beam 
evaporation [13], sol–gel coating [14], chemical 
vapor deposition [15], etc. Various characteristics of 
these SnO2 films have been observed to change by 
changing the preparation technique and environment. 
Of all the methods, electron beam-physical 
vapor deposition (EB-PVD) is much preferred for 
many desirable characteristics such as flexible 
deposition parameters, low contamination relatively  
controlled composition, high deposition rates, dense 
coatings, tailored microstructure [16, 17].  
SnO2 films produced by the EB-PVD process 
usually have a good surface finish and a uniform 
microstructure. The versatility of the EB-PVD 
process is very wide and friendly to environment and 
new films and materials continue to be developed. In 
the present study were prepared SnO2 nanostructured 
thin films with 500 nm thickness onto glass substrate 
by EB-PVD at various substrate temperatures.  
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 3 – 2013, ISSN 1453 – 083X 
 
 
The influence of substrate temperature on 
structural and morphological properties of 
nanostructured SnO2  thin films were studied using 
Scanning and Transmission Electron Microscopy 
(SEM, TEM) and  Atomic Force Microscope (AFM). 
 
2. Experimental part 
 
SnO2 thin films were deposited using electron 
beam evaporation of SnO2 powder (Sigma Aldrich, 
purity 99.99%) as a starting material onto high-
quality microscope glass substrates using tungsten 
crucibles. The substrates were chemically cleaned and 
by glow discharge 30 mA for 6 minutes. The 
temperature of the glass substrates during the electron 
beam evaporation was maintained at different values 
of 300 K, 373 K, 443K, 583 K in order to study the 
temperature’s influence on the properties of the 
obtained films. The system was pumped to a base 
pressure of less than 10-3 Pa before deposition and O2 
was injected into the chamber during evaporation at a 
partial pressure below 10-4 Pa. The substrate was set 
at a distance of 56 cm from the source and rotated at 
20 rpm during deposition to obtain uniform and 
homogeneous films. The deposition parameters were 
optimized to reduce the film roughness. Thickness of 
film and rate of its deposition were controlled with 
the help of an in situ quartz crystal thickness monitor. 
Thickness of the film was about 500 nm and the 
deposition rate was set as 20 Å/sec. The TEM 
investigation was performed on a Philips CM-120 
electronic microscope with an accelerating voltage of 
120 kV. The surface morphology for SnO2 
nanostructured thin films was studied by Atomic 
Force Microscope (AFM, model: Solver PRO-M) and 
scanning electronic microscope (SEM, model: FEI 
Nova NanoSEM 630). 
 
3. Results and discussion 
 
Selected area electron diffraction (SAED) 
patterns were taken from a selected area of the SnO2 
thin films. In Fig.1 is shown the SAED pattern of the 
SnO2 thin film deposited at substrate temperature of 
300 K. The seven intense diffraction rings shown are 
corresponding to diffraction from (101), (111), (210), 
(211), (310), (320) and (321) crystallographic planes. 
The SnO2 thin film deposited at 300 K exhibits the 
polycrystalline structure and corresponds to a 
tetragonal rutile structure.  
 
 
 
Fig. 1. SAED pattern of the SnO2 thin film deposited at substrate temperature of 300 K 
 
Fig. 2 shows bright-field transmission electron 
microscopy (BF-TEM) image recorded from plan 
view specimen, showing that SnO2 thin films exhibit 
a grainy structure which consists of many small 
grains of relatively uniform size forming a 
morphologically homogeneous structure. 
The size distribution of the crystallites, are 
plotted in Fig. 3. The distributions of grain sizes, as 
measured from BF-TEM images, were fitted to the 
lognormal curves [18, 19]. The mean grain size was 
found to be around of 9.48nm. Table 1 shows the 
average particle size varies with the substrate 
temperature. Note that the maximum average size of 
40.78nm of nanoparticles was obtained at 
temperatures of 373K.  
At a temperature of 300K, the average particle 
size is the smallest value, i.e. 9.48nm. At 
temperatures of 443K and 583K, nanoparticles 
average size decreases to 17.16nm and 13.18nm, 
respectively. 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 3 – 2013, ISSN 1453 – 083X 
 
 
 
 
  
Fig. 2. BF-TEM images of the  
SnO2 thin film 
Fig. 3. The distribution curve of the diameters 
of the crystalline grains of SnO2 thin films 
 
Table 1. Some characteristics of SnO2 thin films 
 
Substrate 
temperature  
Film 
thickness 
Mean 
grain size 
Grain 
shape 
[K] [nm]  
300  500  9.48  spherical 
373  500  40.78  spherical 
443  500  17.16  spherical 
583  500  13.18  spherical 
 
We find that spherical nanoparticles retain all 
four temperatures [20, 21].  
The structure of the thin films is crystalline at a 
substrate temperature of 300 K, and it is noticed 
become amorphous at 583 K.  
Another method of investigating the structure of 
SnO2 nanostructured thin films is atomic force 
microscopy (AFM). By this method it has been 
determined the roughness of the samples studied. Fig. 
3 shows 2D and 3D images of SnO2 samples obtained 
at temperatures of 300 K (a) 373 K (b)  443 K(c) and 
583 K(d) and the 500nm thickness.  
Table 2 shows roughness parameters (average 
roughness, Sa, root square average, Sq) at samples 
with thickness of 500 nm obtained at temperatures of 
300, 373, 443, and 583 K. 
 
 
a) 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 3 – 2013, ISSN 1453 – 083X 
 
 
 
b) 
 
c) 
               
d) 
 
Fig. 3. 2D (left) and 3D (right) images of SnO2 thin films with thickness of 500 nm obtained at 
temperatures of 300K (a) 373K (b) 443K (c) and 583K (d) 
 
Table 2 Some roughness parameters of SnO2 thin films 
 
Substrate 
temperature  
Film 
thickness  
Average 
roughness, Sa 
Root mean 
square, Sq  
[K] [nm] 
300  500  3.1966  4.06847 
373  500  2.31532  2.99308 
443  500  2.20535  2.81901 
583  500  34.3865  43.9978 
  
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 3 – 2013, ISSN 1453 – 083X 
 
 
Studying the surface topography of SnO2 thin 
films thus obtained was found that surface 
morphology of the substrate is influenced by 
temperature. Very small values of roughness of SnO2 
nanostructures thin films at temperatures of 300, 373, 
443K, and a much increased value at 583K. This 
different behavior may be due to the amorphous 
structure of the sample at this temperature, confirmed 
by the TEM analysis [20, 21]. 
Because SnO2 nanostructured thin films have a 
low electrical conductivity, their research by scanning 
electron microscopy is difficult. For this reason films 
were covered with a gold layer with a thickness of 5Å 
using Edwards AUTO 500 equipment. In this case, 
the SEM study was performed with an accelerating 
high voltage of electrons of 10kV and a magnification 
of 30,000x. 
The images presented in fig. 4 show that for the 
same film thickness of 500nm, deposited layer 
structure is influenced by the substrate temperature. 
Thus, Fig. 4a shows the image of a film deposited at 
300 K consisting of islands composed of 
nanoparticles whose size varies between 133.7 to 
188.8 nm. At a substrate temperature of 373K, image 
shown in fig.4b, the coating consists of islands joined 
together and that includes nanoparticles whose 
dimensions range from 104.2 to 178.3nm. At a 
substrate temperature of 443K, Fig. 4c, the thin film 
tends to appear uniformly encompassing irregular 
particles of size 133.2-570.3nm arranged disorderly. 
Films obtained at a support temperature of 583K, 
fig.4c, are smooth including nanoparticles uniformly 
arranged with irregular polygonal shapes and sizes of 
276.4-660.4nm. 
 
  
a) b) 
  
c) d) 
Fig. 4. SEM images of SnO2 nanostructured thin films with thickness of 500 nm obtained at 
temperatures of 300 K (a) 373 K (b) 443 K(c) and 583 K(d) 
 
4. Conclusions 
 
By EB-PVD method, we prepared SnO2 
nanostructured thin films with thickness 500 nm on 
glass substrates, at different temperatures of 300, 373, 
443 and 583K. We investigated structural and 
morphological properties of the thin films thus 
obtained using TEM, AFM and SEM techniques. The 
sample obtained at 373K has the highest average size 
of nanoparticles, 40.78nm, while those obtained at 
300K have the lowest average size of nanoparticles, 
9.48nm. Nanoparticles have a spherical shape and it 
is not influenced by the change of the substrate 
temperature. Roughness parameters show different 
values to changes in the substrate temperature. The 
greatest roughness parameters of the SnO2 thin film 
corresponding to a support temperature of 583K when 
the film is in amorphous state.   
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 3 – 2013, ISSN 1453 – 083X 
 
 
Structural and morphological properties were 
studied, proving to be very sensitive to the change of 
substrate temperature during nanostructuring of SnO2 
thin depositions. The substrate temperature strongly 
influences the structural and the morphological 
properties during nanostructuring of SnO2 thin films, 
which is in good agreement with literature dates [16-
21]. 
 
Acknowledgements 
 
This work was financially supported by the 
Project SOP HRD - TOP ACADEMIC 76822. The 
authors gratefully acknowledge Dr. Gabriel Prodan 
from Ovidius University of Constanta for guidance 
and TEM measurements.  
 
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Influence of Substrate Temperature on Structural and Morphological Properties of SnO2 Nanostructured Thin Films

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Influence of Substrate Temperature on Structural and Morphological Properties of SnO2 Nanostructured Thin Films

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