International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 10, October 2013
ISSN 2319 - 4847
XRD and AFM of recrystallization a-Ge and aGe:In with High Annealing Temperature
Hussein Kh.Al-Lamy1, Ramiz A.AL-Ansari2, Issam M. Ibrahim3 and Maryam Th. AL-Azawi4
1,4
Physics Department, College of Science for Women, Baghdad university
2,3
Physics Department, College of science, Baghdad university
ABSTRACT
a-Ge and a-Ge:In films with thickness (0.25µm) have been deposited by thermal evaporation technique on glass substrate at room
temperature, under vacuum of 10-5 mbar with the rate of deposition equal to 15 oA/sec. These films have been annealed at
different annealing temperatures (673, 773)K.The structural characteristics of the films prepared on glass substrates have been
studied by using X-ray diffraction, which show that the films have amorphous structure for sample annealed at Ta = 673K. The
samples were annealed at 773 K showed a polycrystalline with Face-Center cubic system preferred orientation along (111). The
surface morphological characteristics by atomic force microscope (AFM), were increased in roughness with increasing annealing
temperature for amorphous film but start upward when the films crystallized and also found that the grain size decreases with
increasing annealing temperature for amorphous.
Key word: amorphous a-Ge, recrystallization morphology
1. INTRODUCTION
As cost effective synthetic routes for producing large quantities of high purity size-specific nanoparticles become fully
realized, the next challenge lies in fabricating devices that utilize the unique size-dependent optoelectronic properties
inherent in quantum dot materials. The optoelectronic properties of semiconductor nanocrystals (NCs) have been
rigorously researched and demonstrate desirable capabilities previously unattainable with bulk materials(1). Harnessing
semiconductor NC characteristics to advance the functionality of devices such as solar cells, supercapacitors, and
rechargeable batteries, hinges upon creating a highly ordered cohesive film. Methods of semiconductor NC film
deposition which have been comprehensively investigated include layer-by-layer dip coating (2), spin casting (3), and
plasma enhanced chemical vapor deposition (4).
Ge nanocrystals (NCs) have attracted considerable attention because of their potential applications in non-volatile
memory and integrated optoelectronics, as well as the prospect for discovering new physical phenomena. In contrast to Si
NCs, Ge NCs are expected to show stronger confinement effect due to its large excitonic Bohr radius(∼17 nm) (5).
Nanocrystalline germanium (Ge) is a promising material for the application in printable electronics. Dispersed in
organic liquids and deposited as thin functional film, e.g. as a thin film transistor, the electronic properties of the
nanocrystals (NCs) can be investigated (Holman et al, 2010) (6). In this paper we will fabricate a-Ge:In films and study
recrystallization process at high temperature.
2. Experimental Procedure
a-Ge and a-Ge:In thin film were prepared by thermal evaporation technique on glass substrate at room temperature in
vacuum system supplied by Balzers model [BAE 370]. All samples were prepared under constant condition (presser,
substrate temperature and rat of deposition); the main parameter that control the nature of the film properties is thickness
(0.25µm) and annealing temperature (673,773)K .
The structure of the Ge and Ge:In film grown on glass substrate has been examined by X-ray diffraction using a Philips
X-ray diffractometer system. The source of radiation was Cu(Kα) with wave length λ=1.5406Ǻ , the current was 30mA
and the voltage was 40 kV.
Atomic Force Microscopy studies were recorded by using (Scanning probe Microscope type AA3000), supplied by
Angstrom Advanced Inc. to determine the Nano spikes dimensions range of the prepared Ge and Ge:In on glass substrate
and their statistical distribution .
Volume 2, Issue 10, October 2013
Page 348
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 10, October 2013
ISSN 2319 - 4847
3. RESULTS and DISCUSSION
3.1X-Ray Diffraction Analysis
Structural Characterization of Ge:In Thin Films
It is possible to find the crystallinity structure of the film and its growth nature through the study of X-Ray diffraction
(XRD). The XRD results of Ge and Ge doped with 1% In atoms (Ge:In) films prepared on glass substrate at annealing
temperatures (673,773)K are shown in Figure (4.1) with thickness 0.25µm .We observed that Ge and Ge:In films are a
non-crystalline structure at annealing temperature 673K where no peaks appear, similar variation repeated by Chik et al.
(7)
,Kobayashi et al. (8), Ammar(9) and Akram(10). Further raise of the annealing temperature to 773K, the crystallinity is
improved. At Ta 773K, the peaks become more sharp and the oriented in (111) increase with Ta. The films are fully
transformed into a partial crystalline phase of germanium crystal structure, which has the face-centered cubic structure.
This behavior is in agreement with the results of Ammar (9) ,Abdul F.K. et al. (11) and H. Tsuji et al. (12) .
Figure (1A): XRD patterns of Ge films prepared at different annealing temperature
Figure (1B): XRD patterns of Ge:In films prepared at different annealing temperature
.
Also, we found that the crystal growth which effected by doping the a-Ge by In atoms and this behavior may be
reduce the annealing temperature for recrystallization of a-Ge films. This may be can be interpreted in term that the In
atoms play role of defect center or seed for nucleation and growth of a-Ge flims. In addition, the different peaks in the
Figure are indexed in Table (1) as well as the corresponding values of the inter planar spacing d(hkl) which and compared
with the standard values of ASTM data.
Volume 2, Issue 10, October 2013
Page 349
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 10, October 2013
ISSN 2319 - 4847
Table (1): X-ray diffraction data for Ge and Ge:In compound as thin films
Ta
(K)
773
At Ge
773
At Ge:In
2θ (Deg.)
FWHM
(Deg.)
dhkl Exp.
(Å)
G.S
(Å)
dhkl Std.
(Å)
hkl
phase
27.40
45.62
27.353
45.559
53.976
0.55
0.60
0.709
0.886
0.620
3.2524
140
1.9870
3.2579
1.9895
1.6974
135
109
92
135
3.2665
2.0003
3.2665
2.0003
1.7059
(111)
(220)
(111)
(220)
(311)
Cub./Ge
Cub./Ge
cub./Ge
cub./Ge
cub./Ge
3.2 Morphology Properties of Ge:In Thin Film
The surface morphology of the Ge and Ge:In films as observed from the AFM micrograph confirms that the grains are
uniformly distributed. Figure (2) shows the structure of Ge and Ge:In thin films have been deposited on glass substrates
and annealed at temperature ( 673,773) K. We can notice that Ge and Ge:In/glass films deposited at annealed to 673K are
amorphous, while the films annealed to 773 K are crystalline in nature and the grains are packed very closely.
Table (2) shows the value of average roughness and average grain. It is observed from this table that the average
roughness value increases with increasing the annealing temperature for amorphous film, that due to the rearrangement
of atom in film and reduce the vacancy defect. But decrease in roughness when the films crystallized and also the grain
size decreases with increasing annealing temperature.
(a)
(b)
Figure (2a): AFM image for Ge thin films at (0.25 µm): as deposited and difference Ta (a) 673 K, (b) 773K.
Volume 2, Issue 10, October 2013
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 10, October 2013
ISSN 2319 - 4847
(a)
(b)
Figure (2a): AFM image for Ge:In thin films at (0.25 µm): as deposited and difference T a (a) 673 K, (b) 773K.
Table (2): the value of average roughness, RMS and average grain size
Thickness (µm) and
material
0.25
At Ge
0.25
At Ge:In
Ta (K)
average roughness
(nm)
RMS(nm)
average grain
size (nm)
673
0.192
0.225
109.87
773
1.86
2.25
102.88
673
0.203
0.238
134.7
773
0.687
0.851
71.72
4. Conclusion
We observed that the films have amorphous structure for Ta=673 K using X-ray diffraction. Further raise of the annealing
temperature to 773K, showed a polycrystalline with Face-Center cubic system preferred orientation along (111) the peaks
become more sharp.
The surface morphological characteristics (AFM), was increase in roughness with increasing annealing temperature for
amorphous film but start upward when the films crystallized and also found that the grain size decreases with increasing
annealing temperature for amorphous .
References
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Volume 2, Issue 10, October 2013
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 10, October 2013
ISSN 2319 - 4847
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