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Great blue-shift of luminescence of ZnO nanoparticle array constructed from ZnO quantum dots.

Wang N, Yang Y, Yang G - Nanoscale Res Lett (2011)

Bottom Line: The cathodoluminescence measurements showed that there is a pronounced blue-shift of luminescence comparable to those of the bulk counterpart, which is suggested to originate from ZnO QDs with small size where the quantum confinement effect can work well.The fabrication mechanism of the ZnO nanoparticle array constructed from ZnO QDs was proposed, in which the immiscible-like interaction between ZnO nuclei and Si surface play a key role in the ZnO QDs cluster formation.These investigations showed the fabricated nanostructure has potential applications in ultraviolet emitters.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Optoelectronic Materials and Technologies, Institute of Optoelectronic and Functional Composite Materials, Nanotechnology Research Center, School of Physics & Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, P, R, China. stsygw@mail.sysu.edu.cn.

ABSTRACT
ZnO nanoparticle array has been fabricated on the Si substrate by a simple thermal chemical vapor transport and condensation without any metal catalysts. This ZnO nanoparticles array is constructed from ZnO quantum dots (QDs), and half-embedded in the amorphous silicon oxide layer on the surface of the Si substrate. The cathodoluminescence measurements showed that there is a pronounced blue-shift of luminescence comparable to those of the bulk counterpart, which is suggested to originate from ZnO QDs with small size where the quantum confinement effect can work well. The fabrication mechanism of the ZnO nanoparticle array constructed from ZnO QDs was proposed, in which the immiscible-like interaction between ZnO nuclei and Si surface play a key role in the ZnO QDs cluster formation. These investigations showed the fabricated nanostructure has potential applications in ultraviolet emitters.

No MeSH data available.


Related in: MedlinePlus

The dimension of QDs dependence of band gap according to formula (1) and the inset of the relevant emission wavelength dependent on the dimension of QDs. The triangle spot signifies the energy and wavelength which are related to the experimental peak of 363 nm.
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Figure 4: The dimension of QDs dependence of band gap according to formula (1) and the inset of the relevant emission wavelength dependent on the dimension of QDs. The triangle spot signifies the energy and wavelength which are related to the experimental peak of 363 nm.

Mentions: where ћ is the Planck's constant, R is the radius of ZnO QDs, and are, respectively, the effective masses of electron and hole (taking and [27]), E(gap, bulk) is the bulk ZnO band gap (3.377 eV), and is the exciton-binding energy (60 meV [2]). Based on Equation 1, we can obtain the relationship between the size and band gap of ZnO QDs as shown in Figure 4. In our case, the radius of ZnO QDs is in the range of 1.6-6.1 nm are also shown in Figure 4. The corresponding band gap and emission wavelength ranges of the prepared ZnO QDs with the radius of 1.6-6.5 nm are also shown in Figure 4. Meanwhile, the peak of 363 nm in the CL spectrum in Figure 3c is corresponding to the size of 5.7 nm for ZnO QDs according to Equation 1. Therefore, the experimental observations are consistent with the theoretical values in our studies. These results thus show that the great blue-shift compared to bulk ZnO is attributed to the quantum size confinement. However, the theoretical emission peak of ZnO QDs with the radius in 1.6-6.1 nm seems about 340 nm that is corresponding to the average radius of the fabricated ZnO QDs in our case based on Equation 1. In fact, the experimental peak actually shifts to the low energy or high wavelength in Figure 4. As we know, the intensity of emission of big QDs is stronger than that of small QDs. Therefore, the emission from big QDs is easily measured in experiment, which cases the measured emission peak shifting to the low energy or the high wavelength as shown in Figure 4.


Great blue-shift of luminescence of ZnO nanoparticle array constructed from ZnO quantum dots.

Wang N, Yang Y, Yang G - Nanoscale Res Lett (2011)

The dimension of QDs dependence of band gap according to formula (1) and the inset of the relevant emission wavelength dependent on the dimension of QDs. The triangle spot signifies the energy and wavelength which are related to the experimental peak of 363 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211426&req=5

Figure 4: The dimension of QDs dependence of band gap according to formula (1) and the inset of the relevant emission wavelength dependent on the dimension of QDs. The triangle spot signifies the energy and wavelength which are related to the experimental peak of 363 nm.
Mentions: where ћ is the Planck's constant, R is the radius of ZnO QDs, and are, respectively, the effective masses of electron and hole (taking and [27]), E(gap, bulk) is the bulk ZnO band gap (3.377 eV), and is the exciton-binding energy (60 meV [2]). Based on Equation 1, we can obtain the relationship between the size and band gap of ZnO QDs as shown in Figure 4. In our case, the radius of ZnO QDs is in the range of 1.6-6.1 nm are also shown in Figure 4. The corresponding band gap and emission wavelength ranges of the prepared ZnO QDs with the radius of 1.6-6.5 nm are also shown in Figure 4. Meanwhile, the peak of 363 nm in the CL spectrum in Figure 3c is corresponding to the size of 5.7 nm for ZnO QDs according to Equation 1. Therefore, the experimental observations are consistent with the theoretical values in our studies. These results thus show that the great blue-shift compared to bulk ZnO is attributed to the quantum size confinement. However, the theoretical emission peak of ZnO QDs with the radius in 1.6-6.1 nm seems about 340 nm that is corresponding to the average radius of the fabricated ZnO QDs in our case based on Equation 1. In fact, the experimental peak actually shifts to the low energy or high wavelength in Figure 4. As we know, the intensity of emission of big QDs is stronger than that of small QDs. Therefore, the emission from big QDs is easily measured in experiment, which cases the measured emission peak shifting to the low energy or the high wavelength as shown in Figure 4.

Bottom Line: The cathodoluminescence measurements showed that there is a pronounced blue-shift of luminescence comparable to those of the bulk counterpart, which is suggested to originate from ZnO QDs with small size where the quantum confinement effect can work well.The fabrication mechanism of the ZnO nanoparticle array constructed from ZnO QDs was proposed, in which the immiscible-like interaction between ZnO nuclei and Si surface play a key role in the ZnO QDs cluster formation.These investigations showed the fabricated nanostructure has potential applications in ultraviolet emitters.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Optoelectronic Materials and Technologies, Institute of Optoelectronic and Functional Composite Materials, Nanotechnology Research Center, School of Physics & Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, P, R, China. stsygw@mail.sysu.edu.cn.

ABSTRACT
ZnO nanoparticle array has been fabricated on the Si substrate by a simple thermal chemical vapor transport and condensation without any metal catalysts. This ZnO nanoparticles array is constructed from ZnO quantum dots (QDs), and half-embedded in the amorphous silicon oxide layer on the surface of the Si substrate. The cathodoluminescence measurements showed that there is a pronounced blue-shift of luminescence comparable to those of the bulk counterpart, which is suggested to originate from ZnO QDs with small size where the quantum confinement effect can work well. The fabrication mechanism of the ZnO nanoparticle array constructed from ZnO QDs was proposed, in which the immiscible-like interaction between ZnO nuclei and Si surface play a key role in the ZnO QDs cluster formation. These investigations showed the fabricated nanostructure has potential applications in ultraviolet emitters.

No MeSH data available.


Related in: MedlinePlus