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Highly conductive and pure gold nanostructures grown by electron beam induced deposition

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ABSTRACT

This work introduces an additive direct-write nanofabrication technique for producing extremely conductive gold nanostructures from a commercial metalorganic precursor. Gold content of 91 atomic % (at. %) was achieved by using water as an oxidative enhancer during direct-write deposition. A model was developed based on the deposition rate and the chemical composition, and it explains the surface processes that lead to the increases in gold purity and deposition yield. Co-injection of an oxidative enhancer enabled Focused Electron Beam Induced Deposition (FEBID)—a maskless, resistless deposition method for three dimensional (3D) nanostructures—to directly yield pure gold in a single process step, without post-deposition purification. Gold nanowires displayed resistivity down to 8.8 μΩ cm. This is the highest conductivity achieved so far from FEBID and it opens the possibility of applications in nanoelectronics, such as direct-write contacts to nanomaterials. The increased gold deposition yield and the ultralow carbon level will facilitate future applications such as the fabrication of 3D nanostructures in nanoplasmonics and biomolecule immobilization.

No MeSH data available.


Electrical resistivity measurements.(a) I-V characteristics of the “in-situ” purified FEBID Au nanowire. The inset in (a) shows an SEM image of the used four-point contacts. (b) A measurement series with increasing maximum current from 1.5 mA to 10 mA is shown. The insets in (b) show an AFM image and height profile of the deposited structure.
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f4: Electrical resistivity measurements.(a) I-V characteristics of the “in-situ” purified FEBID Au nanowire. The inset in (a) shows an SEM image of the used four-point contacts. (b) A measurement series with increasing maximum current from 1.5 mA to 10 mA is shown. The insets in (b) show an AFM image and height profile of the deposited structure.

Mentions: For soft testing, the current range through the nanowire was gradually increased. First, low current values limited to 8.2 μA were chosen to avoid current-induced effects, such as electromigration and thermal annealing. The voltage drop between the inner measurement electrodes increased with the increasing current. This resulted in a lower noise level of the calculated resistance, where increasing current ranges were applied until failure (20 mA) of the FEBID-Au nanowire occurred. Conventional FEBID Au (without an oxidative enhancer) resulted in a tunnelling type conductance, as presented in Supplement 4. This also reveals a very high resistivity of 1 Ω cm, which is an indicator of a poor conductor. The conductivity measurements of water-assisted FEBID Au are presented in Fig. 4a,b. Both I-V graphs correspond to ideal ohmic behaviour. More than ten measurements resulted in resistivities from 10.9 μΩ cm down to a best case of 8.8 μΩ cm. To our knowledge, the highest FEBID gold conductivity was achieved by post-deposition purification, resulting in a resistivity of 17 μΩ cm43. For comparison, the bulk resistivity of gold is 2.2 μΩ cm43. With an oxidative enhancement during Au deposition, the resistivity of gold was just 4-fold higher than that of pure gold. This is, by far, the highest-conductivity measurement of FEBID Au obtained so far. The current density of the wire is ~715 kA/mm2, which is high enough for any typical nanoelectronic device application.


Highly conductive and pure gold nanostructures grown by electron beam induced deposition
Electrical resistivity measurements.(a) I-V characteristics of the “in-situ” purified FEBID Au nanowire. The inset in (a) shows an SEM image of the used four-point contacts. (b) A measurement series with increasing maximum current from 1.5 mA to 10 mA is shown. The insets in (b) show an AFM image and height profile of the deposited structure.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5035929&req=5

f4: Electrical resistivity measurements.(a) I-V characteristics of the “in-situ” purified FEBID Au nanowire. The inset in (a) shows an SEM image of the used four-point contacts. (b) A measurement series with increasing maximum current from 1.5 mA to 10 mA is shown. The insets in (b) show an AFM image and height profile of the deposited structure.
Mentions: For soft testing, the current range through the nanowire was gradually increased. First, low current values limited to 8.2 μA were chosen to avoid current-induced effects, such as electromigration and thermal annealing. The voltage drop between the inner measurement electrodes increased with the increasing current. This resulted in a lower noise level of the calculated resistance, where increasing current ranges were applied until failure (20 mA) of the FEBID-Au nanowire occurred. Conventional FEBID Au (without an oxidative enhancer) resulted in a tunnelling type conductance, as presented in Supplement 4. This also reveals a very high resistivity of 1 Ω cm, which is an indicator of a poor conductor. The conductivity measurements of water-assisted FEBID Au are presented in Fig. 4a,b. Both I-V graphs correspond to ideal ohmic behaviour. More than ten measurements resulted in resistivities from 10.9 μΩ cm down to a best case of 8.8 μΩ cm. To our knowledge, the highest FEBID gold conductivity was achieved by post-deposition purification, resulting in a resistivity of 17 μΩ cm43. For comparison, the bulk resistivity of gold is 2.2 μΩ cm43. With an oxidative enhancement during Au deposition, the resistivity of gold was just 4-fold higher than that of pure gold. This is, by far, the highest-conductivity measurement of FEBID Au obtained so far. The current density of the wire is ~715 kA/mm2, which is high enough for any typical nanoelectronic device application.

View Article: PubMed Central - PubMed

ABSTRACT

This work introduces an additive direct-write nanofabrication technique for producing extremely conductive gold nanostructures from a commercial metalorganic precursor. Gold content of 91 atomic % (at. %) was achieved by using water as an oxidative enhancer during direct-write deposition. A model was developed based on the deposition rate and the chemical composition, and it explains the surface processes that lead to the increases in gold purity and deposition yield. Co-injection of an oxidative enhancer enabled Focused Electron Beam Induced Deposition (FEBID)—a maskless, resistless deposition method for three dimensional (3D) nanostructures—to directly yield pure gold in a single process step, without post-deposition purification. Gold nanowires displayed resistivity down to 8.8 μΩ cm. This is the highest conductivity achieved so far from FEBID and it opens the possibility of applications in nanoelectronics, such as direct-write contacts to nanomaterials. The increased gold deposition yield and the ultralow carbon level will facilitate future applications such as the fabrication of 3D nanostructures in nanoplasmonics and biomolecule immobilization.

No MeSH data available.