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Long-term oxidization and phase transition of InN nanotextures.

Sarantopoulou E, Kollia Z, Dražic G, Kobe S, Antonakakis NS - Nanoscale Res Lett (2011)

Bottom Line: The long-term (6 months) oxidization of hcp-InN (wurtzite, InN-w) nanostructures (crystalline/amorphous) synthesized on Si [100] substrates is analyzed.The densely packed layers of InN-w nanostructures (5-40 nm) are shown to be oxidized by atmospheric oxygen via the formation of an intermediate amorphous In-Ox-Ny (indium oxynitride) phase to a final bi-phase hcp-InN/bcc-In2O3 nanotexture.When the oxidized area exceeds the critical size of 5 nm, the amorphous In-Ox-Ny phase eventually undergoes phase transition via a slow chemical reaction of atomic oxygen with the indium atoms, forming a single bcc In2O3 phase.

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Affiliation: National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635, Greece. esarant@eie.gr.

ABSTRACT
The long-term (6 months) oxidization of hcp-InN (wurtzite, InN-w) nanostructures (crystalline/amorphous) synthesized on Si [100] substrates is analyzed. The densely packed layers of InN-w nanostructures (5-40 nm) are shown to be oxidized by atmospheric oxygen via the formation of an intermediate amorphous In-Ox-Ny (indium oxynitride) phase to a final bi-phase hcp-InN/bcc-In2O3 nanotexture. High-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy and selected area electron diffraction are used to identify amorphous In-Ox-Ny oxynitride phase. When the oxidized area exceeds the critical size of 5 nm, the amorphous In-Ox-Ny phase eventually undergoes phase transition via a slow chemical reaction of atomic oxygen with the indium atoms, forming a single bcc In2O3 phase.

No MeSH data available.


SEM image of InN film. (a) SEM image of an InN film deposited on a Si substrate showing the aggregation of dendrite-like structures. Two spherical droplets are indicated on the film surface. (b) SEM image of the InN film deposited on a Si substrate showing the dendrite fractal structure. (c) EDXS of a droplet indicating that InN is formed in the plume.
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Figure 2: SEM image of InN film. (a) SEM image of an InN film deposited on a Si substrate showing the aggregation of dendrite-like structures. Two spherical droplets are indicated on the film surface. (b) SEM image of the InN film deposited on a Si substrate showing the dendrite fractal structure. (c) EDXS of a droplet indicating that InN is formed in the plume.

Mentions: A microscale SEM image of an InN film deposited on a Si substrate with 1.2 × 104 laser pulses in nitrogen (105 Pa) is shown in Figure 2a. The InN composites aggregate into dendrite nanostructures (Figure 2b). Besides the fractal structure, some spherical droplets of InN or indium are scattered on the substrate (Figure 2a). The indium droplets are ejected from the indium target because of its relatively low melting point. The efficiency of droplet's formation depends on the experimental conditions. For example, the formation of InN droplets by metalorganic vapor phase epitaxy or metalorganic chemical vapor deposition was due to indium surface segregation when the ammonia concentration was insufficient [26,27]. Once a droplet attains its critical size, it becomes thermodynamically stable and continues to grow [18]. At the same time, efficient nitridation of droplets is taking place either on the target's surface or in the plume following laser ablation at 157 nm [17-19].


Long-term oxidization and phase transition of InN nanotextures.

Sarantopoulou E, Kollia Z, Dražic G, Kobe S, Antonakakis NS - Nanoscale Res Lett (2011)

SEM image of InN film. (a) SEM image of an InN film deposited on a Si substrate showing the aggregation of dendrite-like structures. Two spherical droplets are indicated on the film surface. (b) SEM image of the InN film deposited on a Si substrate showing the dendrite fractal structure. (c) EDXS of a droplet indicating that InN is formed in the plume.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211480&req=5

Figure 2: SEM image of InN film. (a) SEM image of an InN film deposited on a Si substrate showing the aggregation of dendrite-like structures. Two spherical droplets are indicated on the film surface. (b) SEM image of the InN film deposited on a Si substrate showing the dendrite fractal structure. (c) EDXS of a droplet indicating that InN is formed in the plume.
Mentions: A microscale SEM image of an InN film deposited on a Si substrate with 1.2 × 104 laser pulses in nitrogen (105 Pa) is shown in Figure 2a. The InN composites aggregate into dendrite nanostructures (Figure 2b). Besides the fractal structure, some spherical droplets of InN or indium are scattered on the substrate (Figure 2a). The indium droplets are ejected from the indium target because of its relatively low melting point. The efficiency of droplet's formation depends on the experimental conditions. For example, the formation of InN droplets by metalorganic vapor phase epitaxy or metalorganic chemical vapor deposition was due to indium surface segregation when the ammonia concentration was insufficient [26,27]. Once a droplet attains its critical size, it becomes thermodynamically stable and continues to grow [18]. At the same time, efficient nitridation of droplets is taking place either on the target's surface or in the plume following laser ablation at 157 nm [17-19].

Bottom Line: The long-term (6 months) oxidization of hcp-InN (wurtzite, InN-w) nanostructures (crystalline/amorphous) synthesized on Si [100] substrates is analyzed.The densely packed layers of InN-w nanostructures (5-40 nm) are shown to be oxidized by atmospheric oxygen via the formation of an intermediate amorphous In-Ox-Ny (indium oxynitride) phase to a final bi-phase hcp-InN/bcc-In2O3 nanotexture.When the oxidized area exceeds the critical size of 5 nm, the amorphous In-Ox-Ny phase eventually undergoes phase transition via a slow chemical reaction of atomic oxygen with the indium atoms, forming a single bcc In2O3 phase.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens 11635, Greece. esarant@eie.gr.

ABSTRACT
The long-term (6 months) oxidization of hcp-InN (wurtzite, InN-w) nanostructures (crystalline/amorphous) synthesized on Si [100] substrates is analyzed. The densely packed layers of InN-w nanostructures (5-40 nm) are shown to be oxidized by atmospheric oxygen via the formation of an intermediate amorphous In-Ox-Ny (indium oxynitride) phase to a final bi-phase hcp-InN/bcc-In2O3 nanotexture. High-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy and selected area electron diffraction are used to identify amorphous In-Ox-Ny oxynitride phase. When the oxidized area exceeds the critical size of 5 nm, the amorphous In-Ox-Ny phase eventually undergoes phase transition via a slow chemical reaction of atomic oxygen with the indium atoms, forming a single bcc In2O3 phase.

No MeSH data available.