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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

AFM images of the OTS SAM surfaces. (a, c) Topographic images of OTS SAMs. (b, d) AFM images with lateral force mode on the structured SAMs. The darker regions correspond to lower friction areas consisting of hydrophobic silane SAM.
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Figure 3: AFM images of the OTS SAM surfaces. (a, c) Topographic images of OTS SAMs. (b, d) AFM images with lateral force mode on the structured SAMs. The darker regions correspond to lower friction areas consisting of hydrophobic silane SAM.

Mentions: Figure 1 showed the scheme of ZnO patterning process on a silicon surface. To fabricate the nanopatterned ZnO nanorods, we used a polymer mask which was made by NIL. Figure 2 showed SEM images of nanopattern obtained from NIL results on the SiO2/Si substrates, giving a square lattice of circular pillars of 300 nm diameter with a 200 nm pitch. Figure 2a,b depicted before and after reactive ion etching, respectively. Figure 2c,d showed lines of 300 nm width with a pitch of 200 nm before and after reactive ion etching, respectively. As can be seen in Figure 2, the imprint process can reproducibly print nanostructures with high fidelity over large area. The thickness of the polymer nanostructures was dependent on the height of the molds. The polymer islands were acted as masks. The polymer mask was then subjected to a brief oxygen plasma step to remove the intermediate layer between the bumps and expose the silicon oxide surface. The power and duration of the plasma exposure were chosen in such a way as to result in the removal of the continuous thin intermediate layer of the polymer. The subsequent exposure to OTS vapors resulted in selective silanization only on the exposed silicon oxide region, giving OTS SAMs. After lift-off of the polymer mask, the surfaces of the patterned SAMs were evaluated by AFM with contact and lateral force microscopy (LFM), respectively. Figure 3a,c presented the topographies of a binary pattern consisting of the methyl (-CH3) of OTS SAMs and hydroxyl (-OH) terminal group of SiO2 surface. Figure 3b,d showed that the SiO2 surface terminated with -OH group produced the regions of high friction due to the strong interactions between the AFM tip and the surface while the AFM tip experienced low torsion in the regions of OTS terminated by the methyl functional group. This difference yielded a strong contrast when imaged by LFM [14,15].


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

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

AFM images of the OTS SAM surfaces. (a, c) Topographic images of OTS SAMs. (b, d) AFM images with lateral force mode on the structured SAMs. The darker regions correspond to lower friction areas consisting of hydrophobic silane SAM.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: AFM images of the OTS SAM surfaces. (a, c) Topographic images of OTS SAMs. (b, d) AFM images with lateral force mode on the structured SAMs. The darker regions correspond to lower friction areas consisting of hydrophobic silane SAM.
Mentions: Figure 1 showed the scheme of ZnO patterning process on a silicon surface. To fabricate the nanopatterned ZnO nanorods, we used a polymer mask which was made by NIL. Figure 2 showed SEM images of nanopattern obtained from NIL results on the SiO2/Si substrates, giving a square lattice of circular pillars of 300 nm diameter with a 200 nm pitch. Figure 2a,b depicted before and after reactive ion etching, respectively. Figure 2c,d showed lines of 300 nm width with a pitch of 200 nm before and after reactive ion etching, respectively. As can be seen in Figure 2, the imprint process can reproducibly print nanostructures with high fidelity over large area. The thickness of the polymer nanostructures was dependent on the height of the molds. The polymer islands were acted as masks. The polymer mask was then subjected to a brief oxygen plasma step to remove the intermediate layer between the bumps and expose the silicon oxide surface. The power and duration of the plasma exposure were chosen in such a way as to result in the removal of the continuous thin intermediate layer of the polymer. The subsequent exposure to OTS vapors resulted in selective silanization only on the exposed silicon oxide region, giving OTS SAMs. After lift-off of the polymer mask, the surfaces of the patterned SAMs were evaluated by AFM with contact and lateral force microscopy (LFM), respectively. Figure 3a,c presented the topographies of a binary pattern consisting of the methyl (-CH3) of OTS SAMs and hydroxyl (-OH) terminal group of SiO2 surface. Figure 3b,d showed that the SiO2 surface terminated with -OH group produced the regions of high friction due to the strong interactions between the AFM tip and the surface while the AFM tip experienced low torsion in the regions of OTS terminated by the methyl functional group. This difference yielded a strong contrast when imaged by LFM [14,15].

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