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Selective patterning of ZnO nanorods on silicon substrates using nanoimprint lithography.

Jung MH, Lee H - Nanoscale Res Lett (2011)

Bottom Line: It was found that the nucleation and initial growth of the crystalline ZnO were proceeded only on the ZnO seed layer, not on the silicon oxide surface.Since the oxygen vacancies on ZnO nanorods serve as strong binding sites for absorption of various organic and inorganic molecules.Consequently, a nano-patterning of the crystalline ZnO nanorods grown from the seed layer treated with plasma may give the versatile applications for the electronics devices.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Creative Research Initiative, Center for Smart Molecular Memory, Department of Chemistry, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon 440-746, Republic of Korea. hyoyoung@skku.edu.

ABSTRACT
In this research, nanoimprint lithography (NIL) was used for patterning crystalline zinc oxide (ZnO) nanorods on the silicon substrate. To fabricate nano-patterned ZnO nanorods, patterning of an n-octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on SiO2 substrate was prepared by the polymer mask using NI. The ZnO seed layer was selectively coated only on the hydrophilic SiO2 surface, not on the hydrophobic OTS SAMs surface. The substrate patterned with the ZnO seed layer was treated with the oxygen plasma to oxidize the silicon surface. It was found that the nucleation and initial growth of the crystalline ZnO were proceeded only on the ZnO seed layer, not on the silicon oxide surface. ZnO photoluminescence spectra showed that ZnO nanorods grown from the seed layer treated with plasma showed lower intensity than those untreated with plasma at 378 nm, but higher intensity at 605 nm. It is indicated that the seed layer treated with plasma produced ZnO nanorods that had a more oxygen vacancy than those grown from seed layer untreated with plasma. Since the oxygen vacancies on ZnO nanorods serve as strong binding sites for absorption of various organic and inorganic molecules. Consequently, a nano-patterning of the crystalline ZnO nanorods grown from the seed layer treated with plasma may give the versatile applications for the electronics devices.

No MeSH data available.


Related in: MedlinePlus

SEM images. (a, c) seed layer pattern and (b, d) ZnO pattern grown from the seed layer, respectively.
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Figure 4: SEM images. (a, c) seed layer pattern and (b, d) ZnO pattern grown from the seed layer, respectively.

Mentions: The plasma-treated surface coated with the ZnO seed layer was suspending the wafer facedown in an equimolar aqueous solution (0.1 M) of zinc nitrate hexahydrate [Zn(NO3)2⋅6H2O] and hexamethylenetetramine at 95°C to grow the ZnO nanorods via the hydrothermal method [21-23]. In a typical solution, the pH of the solution was kept at 6-7. It was found that the nucleation and initial growth of the crystalline ZnO were accelerated on the ZnO seed layer, not on the oxidized SiO2 surfaces. The plasma-treated silicon surface should suppress OH- attachment and nucleation toward the center of exposed ZnO regions. Therefore, ZnO nanorods can be grown only on Zn-polar seed layer surfaces [24-26] and the hexamethylenetetramine and amine-mediated additives, which are nonpolar chelating agents [27], would preferentially attach to the nonpolar facets, thereby exposing the polar planes (c-axis) for anisotropic growth. Considering the SiO2 point of zero charge, we speculate that ZnO nucleation on oxidized SiO2 location may be possible if growth pH is held above the pH 2. It is widely accepted as 2 for a zero-charged bulk SiO2. However, formation of an ionic Si-O bond through plasma oxidation deactivated nucleation. This implied that strongly oxidized SiO2 surface suppressed OH- attachment and preferentially allowed to nucleate ZnO only on the ZnO seed layer for the experimental pH ranges (pH 6-7) described here. Figure 4a,c showed SEM images of ZnO seed layer pattern on the SiO2 surface and Figure 4b,d depicted the ZnO nanorod array grown from the ZnO seed layer pattern.


Selective patterning of ZnO nanorods on silicon substrates using nanoimprint lithography.

Jung MH, Lee H - Nanoscale Res Lett (2011)

SEM images. (a, c) seed layer pattern and (b, d) ZnO pattern grown from the seed layer, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211210&req=5

Figure 4: SEM images. (a, c) seed layer pattern and (b, d) ZnO pattern grown from the seed layer, respectively.
Mentions: The plasma-treated surface coated with the ZnO seed layer was suspending the wafer facedown in an equimolar aqueous solution (0.1 M) of zinc nitrate hexahydrate [Zn(NO3)2⋅6H2O] and hexamethylenetetramine at 95°C to grow the ZnO nanorods via the hydrothermal method [21-23]. In a typical solution, the pH of the solution was kept at 6-7. It was found that the nucleation and initial growth of the crystalline ZnO were accelerated on the ZnO seed layer, not on the oxidized SiO2 surfaces. The plasma-treated silicon surface should suppress OH- attachment and nucleation toward the center of exposed ZnO regions. Therefore, ZnO nanorods can be grown only on Zn-polar seed layer surfaces [24-26] and the hexamethylenetetramine and amine-mediated additives, which are nonpolar chelating agents [27], would preferentially attach to the nonpolar facets, thereby exposing the polar planes (c-axis) for anisotropic growth. Considering the SiO2 point of zero charge, we speculate that ZnO nucleation on oxidized SiO2 location may be possible if growth pH is held above the pH 2. It is widely accepted as 2 for a zero-charged bulk SiO2. However, formation of an ionic Si-O bond through plasma oxidation deactivated nucleation. This implied that strongly oxidized SiO2 surface suppressed OH- attachment and preferentially allowed to nucleate ZnO only on the ZnO seed layer for the experimental pH ranges (pH 6-7) described here. Figure 4a,c showed SEM images of ZnO seed layer pattern on the SiO2 surface and Figure 4b,d depicted the ZnO nanorod array grown from the ZnO seed layer pattern.

Bottom Line: It was found that the nucleation and initial growth of the crystalline ZnO were proceeded only on the ZnO seed layer, not on the silicon oxide surface.Since the oxygen vacancies on ZnO nanorods serve as strong binding sites for absorption of various organic and inorganic molecules.Consequently, a nano-patterning of the crystalline ZnO nanorods grown from the seed layer treated with plasma may give the versatile applications for the electronics devices.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Creative Research Initiative, Center for Smart Molecular Memory, Department of Chemistry, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon 440-746, Republic of Korea. hyoyoung@skku.edu.

ABSTRACT
In this research, nanoimprint lithography (NIL) was used for patterning crystalline zinc oxide (ZnO) nanorods on the silicon substrate. To fabricate nano-patterned ZnO nanorods, patterning of an n-octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on SiO2 substrate was prepared by the polymer mask using NI. The ZnO seed layer was selectively coated only on the hydrophilic SiO2 surface, not on the hydrophobic OTS SAMs surface. The substrate patterned with the ZnO seed layer was treated with the oxygen plasma to oxidize the silicon surface. It was found that the nucleation and initial growth of the crystalline ZnO were proceeded only on the ZnO seed layer, not on the silicon oxide surface. ZnO photoluminescence spectra showed that ZnO nanorods grown from the seed layer treated with plasma showed lower intensity than those untreated with plasma at 378 nm, but higher intensity at 605 nm. It is indicated that the seed layer treated with plasma produced ZnO nanorods that had a more oxygen vacancy than those grown from seed layer untreated with plasma. Since the oxygen vacancies on ZnO nanorods serve as strong binding sites for absorption of various organic and inorganic molecules. Consequently, a nano-patterning of the crystalline ZnO nanorods grown from the seed layer treated with plasma may give the versatile applications for the electronics devices.

No MeSH data available.


Related in: MedlinePlus