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Sol-gel synthesized zinc oxide nanorods and their structural and optical investigation for optoelectronic application.

Foo KL, Hashim U, Muhammad K, Voon CH - Nanoscale Res Lett (2014)

Bottom Line: Nanostructured zinc oxide (ZnO) nanorods (NRs) with hexagonal wurtzite structures were synthesized using an easy and low-cost bottom-up hydrothermal growth technique.In addition, the calculated results from the specific models of the refractive index are consistent with the experimental data.The ZnO NRs that grew from the 2-methoxyethanol seeded layer exhibited the smallest grain size (39.18 nm), largest diffracted intensities on the (002) plane, and highest bandgap (3.21 eV).

View Article: PubMed Central - HTML - PubMed

Affiliation: Nano Biochip Research Group, Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis 01000, Malaysia.

ABSTRACT
Nanostructured zinc oxide (ZnO) nanorods (NRs) with hexagonal wurtzite structures were synthesized using an easy and low-cost bottom-up hydrothermal growth technique. ZnO thin films were prepared with the use of four different solvents, namely, methanol, ethanol, isopropanol, and 2-methoxyethanol, and then used as seed layer templates for the subsequent growth of the ZnO NRs. The influences of the different solvents on the structural and optical properties were investigated through scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and photoluminescence. The obtained X-ray diffraction patterns showed that the synthesized ZnO NRs were single crystals and exhibited a preferred orientation along the (002) plane. In addition, the calculated results from the specific models of the refractive index are consistent with the experimental data. The ZnO NRs that grew from the 2-methoxyethanol seeded layer exhibited the smallest grain size (39.18 nm), largest diffracted intensities on the (002) plane, and highest bandgap (3.21 eV).

No MeSH data available.


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Plot of ( α hv) 2 versus the photon energy for different solvent derived ZnO thin films.
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Figure 7: Plot of ( α hv) 2 versus the photon energy for different solvent derived ZnO thin films.

Mentions: where hv is the photon energy, B is the constant, Eg is the bandgap energy, and n is the allowed direct band with the value of ½. The direct bandgap energies for the different solvents used were determined by plotting the corresponding Tauc graphs, that is, (αhv)2 versus hv curves. This method was used to measure the energy difference between the valence and conduction bands. The direct bandgap of the ZnO films was the interception between the tangent to the linear portion of the curve and the hv-axis (Figure 7). The optical bandgaps determined from the curves are summarized in Table 3. The results indicated that the ZnO NRs that were grown with 2-ME for the seed layer preparation showed the highest bandgap (3.21 eV), whereas those grown with the IPA exhibited the lowest bandgap (3.18 eV), which is believed to possess a better conductivity. According to the corresponding bandgap energy (Eg) and absorption band edge (λ) of the bulk ZnO, that is, 367 nm and 3.36 eV, respectively [45], the as-grown ZnO NRs possessed a significantly lower bandgap or exhibited a redshift of Eg from 0.15 to 0.18 eV. This shift can be attributed to the optical confinement effect of the formation of ZnO NRs [46] and the size of the ZnO NRs [47].


Sol-gel synthesized zinc oxide nanorods and their structural and optical investigation for optoelectronic application.

Foo KL, Hashim U, Muhammad K, Voon CH - Nanoscale Res Lett (2014)

Plot of ( α hv) 2 versus the photon energy for different solvent derived ZnO thin films.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150024&req=5

Figure 7: Plot of ( α hv) 2 versus the photon energy for different solvent derived ZnO thin films.
Mentions: where hv is the photon energy, B is the constant, Eg is the bandgap energy, and n is the allowed direct band with the value of ½. The direct bandgap energies for the different solvents used were determined by plotting the corresponding Tauc graphs, that is, (αhv)2 versus hv curves. This method was used to measure the energy difference between the valence and conduction bands. The direct bandgap of the ZnO films was the interception between the tangent to the linear portion of the curve and the hv-axis (Figure 7). The optical bandgaps determined from the curves are summarized in Table 3. The results indicated that the ZnO NRs that were grown with 2-ME for the seed layer preparation showed the highest bandgap (3.21 eV), whereas those grown with the IPA exhibited the lowest bandgap (3.18 eV), which is believed to possess a better conductivity. According to the corresponding bandgap energy (Eg) and absorption band edge (λ) of the bulk ZnO, that is, 367 nm and 3.36 eV, respectively [45], the as-grown ZnO NRs possessed a significantly lower bandgap or exhibited a redshift of Eg from 0.15 to 0.18 eV. This shift can be attributed to the optical confinement effect of the formation of ZnO NRs [46] and the size of the ZnO NRs [47].

Bottom Line: Nanostructured zinc oxide (ZnO) nanorods (NRs) with hexagonal wurtzite structures were synthesized using an easy and low-cost bottom-up hydrothermal growth technique.In addition, the calculated results from the specific models of the refractive index are consistent with the experimental data.The ZnO NRs that grew from the 2-methoxyethanol seeded layer exhibited the smallest grain size (39.18 nm), largest diffracted intensities on the (002) plane, and highest bandgap (3.21 eV).

View Article: PubMed Central - HTML - PubMed

Affiliation: Nano Biochip Research Group, Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Kangar, Perlis 01000, Malaysia.

ABSTRACT
Nanostructured zinc oxide (ZnO) nanorods (NRs) with hexagonal wurtzite structures were synthesized using an easy and low-cost bottom-up hydrothermal growth technique. ZnO thin films were prepared with the use of four different solvents, namely, methanol, ethanol, isopropanol, and 2-methoxyethanol, and then used as seed layer templates for the subsequent growth of the ZnO NRs. The influences of the different solvents on the structural and optical properties were investigated through scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and photoluminescence. The obtained X-ray diffraction patterns showed that the synthesized ZnO NRs were single crystals and exhibited a preferred orientation along the (002) plane. In addition, the calculated results from the specific models of the refractive index are consistent with the experimental data. The ZnO NRs that grew from the 2-methoxyethanol seeded layer exhibited the smallest grain size (39.18 nm), largest diffracted intensities on the (002) plane, and highest bandgap (3.21 eV).

No MeSH data available.


Related in: MedlinePlus