Iaetsd synthesis and investigation of properties in ga asxn1-x

1. Synthesis and Investigation of Properties in GaAsxN1-x
Nano Ternary Semiconductor Thin films
Prof Vedam RamaMurthy1, a
, Alla Srivani 2,b
, G Veeraraghavaiah3,c
Prof and Head of the Department, T.J.P.S College, Guntur, Andhra Pradesh, India
Assistant Professor in Vasi Reddy Venkatadri Institute of Technology (VVIT), Research in
IIT Kharagpur, India
Assistant professor, P.A.S College, Pedanandipadu, Guntur, Andhra Pradesh, India
Abstract: Electron cyclotron resonance-metal organic molecular beam epitaxy has been
used to deposit GaAsxN1-x layers on various substrates. This paper will report on the structural
characterization of this material, as measured by x-ray diffraction and cross-sectional
transmission electron microscopy. GaAsxN1-x layers grown on GaAs appear to be cubic while
those grown on GaP are surprisingly hexagonal. The hexagonal phase is also observed under
some growth conditions in material grown on GaAs, however, the cubic phase can be
obtained by optimizing the parameters, which affect the initial nucleation. Conditions such as
pre-deposition annealing and growth temperature are critical in determining the phase and
crystallinity of the resulting layers. Because of the reduced mismatch between GaN and GaP,
the cubic phase of GaN can be more easily nucleated on GaP substrates than on GaAs wafers
using similar growth conditions.
Key words: GaAsxN1-x semiconductor thin films, Nano size, synthesis, electron
microscopy, MBE
Introduction:-
In recent years, GaAsxN1-x semiconductor thin films and other III-nitride based on wide
band gap have emerged as the leading material for the production of blue light-emitting
devices, blue laser diodes, and Optoelectronic applications. One-dimensional structures with
nanometer sized diameters have great potential for playing an important role in the testing,
understanding of fundamental concepts of the role of dimensionality and size in physical
properties.3
Since the first work of GaAsxN1-x semiconductor thin films nano rods was pre-
pared using a carbon-nano tube-confined reaction,4
many efforts have been devoted to
developing different approaches for synthesizing GaAsxN1-x semiconductor thin films nano
rods. These include metal-catalyzed growth assisted by laser ablation,5
template-induced
growth,6
hot filament chemical vapor deposition,7
and gallium oxide reacted with ammonia.8
±11
GaAsxN1-x semiconductor thin films a nanorods and carbon nanotubes filled with GaN
nanorods have also been synthesized by an arc discharge route.12
Inorganic gallium sources,
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2. such as Ga and Ga2 O, and inorganic catalysts are typically used for the growth of GaAsxN1-x
semiconductor thin films nanorods. The pyrolysis of organo metallic precursors has already
been demonstrated to be a powerful route to the synthesis of nano tubes and filled
nanotubes.13±16
In the present study, we describe the use of a pyrolysis route to prepare
GaAsxN1-x semiconductor thin films nano rods where both the GaAsxN1-x semiconductor thin
films and the catalyst come from organic sources.
Experiment:
In order to prepare the GaAsxN1-x semiconductor thin films nano rods by the pyrolysis route,
we employed a two-stage furnace system fitted with temperature controllers.13±16
The
resulting sample GaAsxN1-x was characterized by high-resolution transmission electron
microscopy ~HRTEM! using a Philips CM-200 FEG equipped with energy dispersive x-ray
spectrometer ~EDS!.To reveal the growth process of the product, HRTEM was used to
examine the general morphology in GaAsxN1-x. In Fig. 1~a!, we show the typical low-
magnification image of the nano-rods. The sizes of the GaAsxN1-x nano rods are typically 2 to
20 mm in length and 25 to 50 nm in diameter. The nano rods are usually straight and uniform.
Carbon nano tubes are also found in the product. The compositions of nano rods are checked
by EDS, which shows that the nano rods of GaAsxN1-x have elemental ratio of Ga to N closes
to 1. Figure 1~b! shows a high-magnification image of part of a nano rod. Digitized images
were then analyzed by fast Hartley transform ~FHT! techniques to reveal details of the local
structure.
Results and Discussion
The inset of Fig. 1 is the corresponding diffraction patterns taken by FHT, which can be
indexed to hexagonal wurtzite GaN. The incidence direction of the electron beam is along
^001& direction. The axis direction of the GaN nano rod is @110#. Polygonal- or spherical-
shaped particles are frequently found at the tip of the nano rods. Figure 2~a! shows a low-
magnification image of a GaN nano rod including its tip. Fig-ure 2~b! shows a high-
magnification image of the interface of the tip and the nano rod. It shows that the tip is
polycrystalline and the nano rod part is mono crystalline. The compositions of the tip and the
nano rod were detected by EDS @Fig. 2~c!#. It shows that there are Fe, Ga, N, and O at the
tip and only GaN in the nano rod part. A small amount of oxygen at the tip might have come
from the remaining oxygen in the quartz tube although the tube was purged with ammonia.
Another possibility is that it may have come from the quartz tube at high temperatures.
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3. FIG: TEM image showing a general view of the GaAsxN1-x nano rods and the carbon
nanotubes in the product high-magnification image of part of a nano rod. Inset is the
corresponding diffraction patterns taken by FHT techniques.
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4. FI: Low-magnification image of a GaAsxN1-x nano rod including its tip, ~b! a high-
magnification image of the interface of the tip and the nano rod, and ~c! EDS spectra taken
from the tip ~upper! and nano rod ~down!, respectively
Conclusion:
position of ferrocene, gallium dimethylamide, and ammonia, iron particles are surrounded by
N, Ga, C, etc. radicals. In the initial stage, segregation of iron occurs, leading to an in-crease
in the size of iron clusters on the surface of quartz tube. Subsequently, Ga and N are
introduced in vapor phase and dissolve in the iron oxide clusters to form liquid catalyst
centers.19
Continuous dissolution of Ga, As and N leads to a supersaturated solution.
GaAsxN1-x nano rod growth takes place by the precipitation from the supersaturated liquid of
the catalyst centers. The overall evolution of nano rod growth following the generation of the
iron catalytic particles by pyrolysis is illustrated in Fig
In summary, we have exploited the pyrolysis route for the synthesis of high quality GaAsxN1-x
nano rods. We believe that this approach can be readily extended to the synthesis of other
group-III-nitride based semiconductor nano rods and nano rods of other materials, which
might offer great opportunities for both fundamental research and technological application
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