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An investigation into the conversion of In2O3 into InN nanowires.

Papageorgiou P, Zervos M, Othonos A - Nanoscale Res Lett (2011)

Bottom Line: The NWs are eliminated above 600°C while long nitridation times at 500 and 600°C did not result into the efficient conversion of In2O3 to InN.We find that the nitridation of In2O3 is effective by using NH3 and H2 or a two-step temperature nitridation process using just NH3 and slower ramp rates.We discuss the nitridation mechanism and its effect on the PL.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nanostructured Materials and Devices Laboratory, Department of Mechanical Engineering, Materials Science Group, School of Engineering, University of Cyprus, P,O, Box 20537, Nicosia, 1678, Cyprus. zervos@ucy.ac.cy.

ABSTRACT
Straight In2O3 nanowires (NWs) with diameters of 50 nm and lengths ≥2 μm have been grown on Si(001) via the wet oxidation of In at 850°C using Au as a catalyst. These exhibited clear peaks in the X-ray diffraction corresponding to the body centred cubic crystal structure of In2O3 while the photoluminescence (PL) spectrum at 300 K consisted of two broad peaks, centred around 400 and 550 nm. The post-growth nitridation of In2O3 NWs was systematically investigated by varying the nitridation temperature between 500 and 900°C, flow of NH3 and nitridation times between 1 and 6 h. The NWs are eliminated above 600°C while long nitridation times at 500 and 600°C did not result into the efficient conversion of In2O3 to InN. We find that the nitridation of In2O3 is effective by using NH3 and H2 or a two-step temperature nitridation process using just NH3 and slower ramp rates. We discuss the nitridation mechanism and its effect on the PL.

No MeSH data available.


Typical SEM image of In2O3 NWs obtained on 1.1 nm Au/Si(001).
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Figure 1: Typical SEM image of In2O3 NWs obtained on 1.1 nm Au/Si(001).

Mentions: Previously, we obtained In2O3 NWs by dry oxidation at 700°C [7]. A high yield of In2O3 NWs with an average diameter of ≈100 nm and lengths of ≈1 μm was obtained on Si(111) and quartz. However, these In2O3 NWs were slightly tapered; their diameters were larger and lengths were shorter compared to the In2O3 NWs obtained here by wet oxidation. Moreover, the distribution of the In2O3 NWs obtained by wet oxidation was far superior and much more uniform compared to those obtained by dry oxidation. A typical image of In2O3 NWs that were obtained at TG = 850°C by wet oxidation is shown in Figure 1. It should be pointed out that a high yield and uniform distribution of In2O3 NWs extending over 1 cm2 was obtained when the distance between the In and the Au/n+Si (001) was ≥15 mm, which led to a light blue-like deposit. The In2O3 NWs have diameters of ≈50 nm, lengths ≥2 μm and exhibited clear peaks in the XRD as shown in Figure 2 by the top curve, corresponding to the body centred cubic (bcc) crystal structure of In2O3 with a = 10.12 Å, in agreement with Dai et al. who obtained twisted In2O3 NWs by wet oxidation [8]. The In2O3 NWs shown in Figure 1 are straight [9,10] and in our case In2O3 NWs grow by a simple chemical route involving the following reaction: 2In + 3H2O → In2O3 + 3H2 [8]. Wet oxidation is a facile method and generally occurs faster than dry oxidation. No NWs were obtained on plain Si(001), suggesting the growth of In2O3 NWs occurs via the vapour-liquid-solid (VLS) mechanism with Au acting as the catalyst. In this case, Au NPs absorb In until they become supersaturated after which In2O3 NW growth commences via the reaction of In with H2O as outlined above.


An investigation into the conversion of In2O3 into InN nanowires.

Papageorgiou P, Zervos M, Othonos A - Nanoscale Res Lett (2011)

Typical SEM image of In2O3 NWs obtained on 1.1 nm Au/Si(001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211398&req=5

Figure 1: Typical SEM image of In2O3 NWs obtained on 1.1 nm Au/Si(001).
Mentions: Previously, we obtained In2O3 NWs by dry oxidation at 700°C [7]. A high yield of In2O3 NWs with an average diameter of ≈100 nm and lengths of ≈1 μm was obtained on Si(111) and quartz. However, these In2O3 NWs were slightly tapered; their diameters were larger and lengths were shorter compared to the In2O3 NWs obtained here by wet oxidation. Moreover, the distribution of the In2O3 NWs obtained by wet oxidation was far superior and much more uniform compared to those obtained by dry oxidation. A typical image of In2O3 NWs that were obtained at TG = 850°C by wet oxidation is shown in Figure 1. It should be pointed out that a high yield and uniform distribution of In2O3 NWs extending over 1 cm2 was obtained when the distance between the In and the Au/n+Si (001) was ≥15 mm, which led to a light blue-like deposit. The In2O3 NWs have diameters of ≈50 nm, lengths ≥2 μm and exhibited clear peaks in the XRD as shown in Figure 2 by the top curve, corresponding to the body centred cubic (bcc) crystal structure of In2O3 with a = 10.12 Å, in agreement with Dai et al. who obtained twisted In2O3 NWs by wet oxidation [8]. The In2O3 NWs shown in Figure 1 are straight [9,10] and in our case In2O3 NWs grow by a simple chemical route involving the following reaction: 2In + 3H2O → In2O3 + 3H2 [8]. Wet oxidation is a facile method and generally occurs faster than dry oxidation. No NWs were obtained on plain Si(001), suggesting the growth of In2O3 NWs occurs via the vapour-liquid-solid (VLS) mechanism with Au acting as the catalyst. In this case, Au NPs absorb In until they become supersaturated after which In2O3 NW growth commences via the reaction of In with H2O as outlined above.

Bottom Line: The NWs are eliminated above 600°C while long nitridation times at 500 and 600°C did not result into the efficient conversion of In2O3 to InN.We find that the nitridation of In2O3 is effective by using NH3 and H2 or a two-step temperature nitridation process using just NH3 and slower ramp rates.We discuss the nitridation mechanism and its effect on the PL.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nanostructured Materials and Devices Laboratory, Department of Mechanical Engineering, Materials Science Group, School of Engineering, University of Cyprus, P,O, Box 20537, Nicosia, 1678, Cyprus. zervos@ucy.ac.cy.

ABSTRACT
Straight In2O3 nanowires (NWs) with diameters of 50 nm and lengths ≥2 μm have been grown on Si(001) via the wet oxidation of In at 850°C using Au as a catalyst. These exhibited clear peaks in the X-ray diffraction corresponding to the body centred cubic crystal structure of In2O3 while the photoluminescence (PL) spectrum at 300 K consisted of two broad peaks, centred around 400 and 550 nm. The post-growth nitridation of In2O3 NWs was systematically investigated by varying the nitridation temperature between 500 and 900°C, flow of NH3 and nitridation times between 1 and 6 h. The NWs are eliminated above 600°C while long nitridation times at 500 and 600°C did not result into the efficient conversion of In2O3 to InN. We find that the nitridation of In2O3 is effective by using NH3 and H2 or a two-step temperature nitridation process using just NH3 and slower ramp rates. We discuss the nitridation mechanism and its effect on the PL.

No MeSH data available.