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Fabrication of ultrahigh-density nanowires by electrochemical nanolithography.

Chen F, Jiang H, Kiefer AM, Clausen AM, Ting YH, Wendt AE, Ding B, Lagally MG - Nanoscale Res Lett (2011)

Bottom Line: An approach has been developed to produce silver nanoparticles (AgNPs) rapidly on semiconductor wafers using electrochemical deposition.The closely packed AgNPs have a density of up to 1.4 × 1011 cm-2 with good size uniformity.AgNPs retain their shape and position on the substrate when used as nanomasks for producing ultrahigh-density vertical nanowire arrays with controllable size, making it a one-step nanolithography technique.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Wisconsin-Madison, Madison, WI 53706, USA. lagally@engr.wisc.edu.

ABSTRACT
An approach has been developed to produce silver nanoparticles (AgNPs) rapidly on semiconductor wafers using electrochemical deposition. The closely packed AgNPs have a density of up to 1.4 × 1011 cm-2 with good size uniformity. AgNPs retain their shape and position on the substrate when used as nanomasks for producing ultrahigh-density vertical nanowire arrays with controllable size, making it a one-step nanolithography technique. We demonstrate this method on Si/SiGe multilayer superlattices using electrochemical nanopatterning and plasma etching to obtain high-density Si/SiGe multilayer superlattice nanowires.

No MeSH data available.


Related in: MedlinePlus

SEM and HRTEM images of etched nanowires. (a) 45°-tilted view of nanowires with Ag nanoparticle caps. (b) Side view of nanowires, the Ag particles are removed by HNO3. Some nanowires are bent because of air blow-drying of the sample after the dip in HNO3 and rinsing in DI water. (c) Cross-sectional TEM image of superlattice nanowires with Ag particles retained. The darker lines are the SiGe alloy. The lateral width of the SiGe layer is smaller than the Si layer because Ge etches faster than pure Si in a SF6/C2H2F4 plasma. (d) HRTEM image showing the atomic detail of different sections. The dashed lines guide the eye to the interfaces between Si and SiGe.
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Figure 5: SEM and HRTEM images of etched nanowires. (a) 45°-tilted view of nanowires with Ag nanoparticle caps. (b) Side view of nanowires, the Ag particles are removed by HNO3. Some nanowires are bent because of air blow-drying of the sample after the dip in HNO3 and rinsing in DI water. (c) Cross-sectional TEM image of superlattice nanowires with Ag particles retained. The darker lines are the SiGe alloy. The lateral width of the SiGe layer is smaller than the Si layer because Ge etches faster than pure Si in a SF6/C2H2F4 plasma. (d) HRTEM image showing the atomic detail of different sections. The dashed lines guide the eye to the interfaces between Si and SiGe.

Mentions: Using the AgNPs as a mask, vertically aligned superlattice nanowires are etched, as shown in Figure 5, which shows both scanning electron microscopy and transmission electron microscopy images. If a single etching time is too long, because sidewall etching occurs simultaneously, the top of the nanowires (closest to the plasma source) will be etched away and the nanowire will form a tapered structure (Figure 5c). This problem can be overcome by depositing a fluorocarbon film (using C4F8 as precursor) on the sidewall during etching [34]. It protects the sidewall from being further etched, and it can be removed with an O2 plasma or HF afterward. The details of deep reactive-ion etching (RIE) can be found in Ref. [35].


Fabrication of ultrahigh-density nanowires by electrochemical nanolithography.

Chen F, Jiang H, Kiefer AM, Clausen AM, Ting YH, Wendt AE, Ding B, Lagally MG - Nanoscale Res Lett (2011)

SEM and HRTEM images of etched nanowires. (a) 45°-tilted view of nanowires with Ag nanoparticle caps. (b) Side view of nanowires, the Ag particles are removed by HNO3. Some nanowires are bent because of air blow-drying of the sample after the dip in HNO3 and rinsing in DI water. (c) Cross-sectional TEM image of superlattice nanowires with Ag particles retained. The darker lines are the SiGe alloy. The lateral width of the SiGe layer is smaller than the Si layer because Ge etches faster than pure Si in a SF6/C2H2F4 plasma. (d) HRTEM image showing the atomic detail of different sections. The dashed lines guide the eye to the interfaces between Si and SiGe.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3211863&req=5

Figure 5: SEM and HRTEM images of etched nanowires. (a) 45°-tilted view of nanowires with Ag nanoparticle caps. (b) Side view of nanowires, the Ag particles are removed by HNO3. Some nanowires are bent because of air blow-drying of the sample after the dip in HNO3 and rinsing in DI water. (c) Cross-sectional TEM image of superlattice nanowires with Ag particles retained. The darker lines are the SiGe alloy. The lateral width of the SiGe layer is smaller than the Si layer because Ge etches faster than pure Si in a SF6/C2H2F4 plasma. (d) HRTEM image showing the atomic detail of different sections. The dashed lines guide the eye to the interfaces between Si and SiGe.
Mentions: Using the AgNPs as a mask, vertically aligned superlattice nanowires are etched, as shown in Figure 5, which shows both scanning electron microscopy and transmission electron microscopy images. If a single etching time is too long, because sidewall etching occurs simultaneously, the top of the nanowires (closest to the plasma source) will be etched away and the nanowire will form a tapered structure (Figure 5c). This problem can be overcome by depositing a fluorocarbon film (using C4F8 as precursor) on the sidewall during etching [34]. It protects the sidewall from being further etched, and it can be removed with an O2 plasma or HF afterward. The details of deep reactive-ion etching (RIE) can be found in Ref. [35].

Bottom Line: An approach has been developed to produce silver nanoparticles (AgNPs) rapidly on semiconductor wafers using electrochemical deposition.The closely packed AgNPs have a density of up to 1.4 × 1011 cm-2 with good size uniformity.AgNPs retain their shape and position on the substrate when used as nanomasks for producing ultrahigh-density vertical nanowire arrays with controllable size, making it a one-step nanolithography technique.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Wisconsin-Madison, Madison, WI 53706, USA. lagally@engr.wisc.edu.

ABSTRACT
An approach has been developed to produce silver nanoparticles (AgNPs) rapidly on semiconductor wafers using electrochemical deposition. The closely packed AgNPs have a density of up to 1.4 × 1011 cm-2 with good size uniformity. AgNPs retain their shape and position on the substrate when used as nanomasks for producing ultrahigh-density vertical nanowire arrays with controllable size, making it a one-step nanolithography technique. We demonstrate this method on Si/SiGe multilayer superlattices using electrochemical nanopatterning and plasma etching to obtain high-density Si/SiGe multilayer superlattice nanowires.

No MeSH data available.


Related in: MedlinePlus