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Maskless Lithography and in situ Visualization of Conductivity of Graphene using Helium Ion Microscopy.

Iberi V, Vlassiouk I, Zhang XG, Matola B, Linn A, Joy DC, Rondinone AJ - Sci Rep (2015)

Bottom Line: The remarkable mechanical and electronic properties of graphene make it an ideal candidate for next generation nanoelectronics.With the recent development of commercial-level single-crystal graphene layers, the potential for manufacturing household graphene-based devices has improved, but significant challenges still remain with regards to patterning the graphene into devices.In the case of graphene supported on a substrate, traditional nanofabrication techniques such as e-beam lithography (EBL) are often used in fabricating graphene nanoribbons but the multi-step processes they require can result in contamination of the graphene with resists and solvents.

View Article: PubMed Central - PubMed

Affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.

ABSTRACT
The remarkable mechanical and electronic properties of graphene make it an ideal candidate for next generation nanoelectronics. With the recent development of commercial-level single-crystal graphene layers, the potential for manufacturing household graphene-based devices has improved, but significant challenges still remain with regards to patterning the graphene into devices. In the case of graphene supported on a substrate, traditional nanofabrication techniques such as e-beam lithography (EBL) are often used in fabricating graphene nanoribbons but the multi-step processes they require can result in contamination of the graphene with resists and solvents. In this letter, we report the utility of scanning helium ion lithography for fabricating functional graphene nanoconductors that are supported directly on a silicon dioxide layer, and we measure the minimum feature size achievable due to limitations imposed by thermal fluctuations and ion scattering during the milling process. Further we demonstrate that ion beams, due to their positive charging nature, may be used to observe and test the conductivity of graphene-based nanoelectronic devices in situ.

No MeSH data available.


Related in: MedlinePlus

(Left panel) SHIM images of graphene-based pads that have been fabricated using direct-write He+ lithography.(Top left) Nonconducting graphene pad due to insufficient supply of electrons through the thin conducting graphene strip (~10 nm). (Middle left) Onset of slight conduction in graphene pad as the width of the conducting strip is increased to 12 nm. Thermal noise is also evident in the pad. (Bottom left) Fully conducting graphene pad with conducting strip width of 14 nm. (Right panel) SEM images of the exact same structures indicating insufficient electrons in the graphene pads (top and middle right) are compensated by the electron beam. Scale bar is 50 nm.
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f1: (Left panel) SHIM images of graphene-based pads that have been fabricated using direct-write He+ lithography.(Top left) Nonconducting graphene pad due to insufficient supply of electrons through the thin conducting graphene strip (~10 nm). (Middle left) Onset of slight conduction in graphene pad as the width of the conducting strip is increased to 12 nm. Thermal noise is also evident in the pad. (Bottom left) Fully conducting graphene pad with conducting strip width of 14 nm. (Right panel) SEM images of the exact same structures indicating insufficient electrons in the graphene pads (top and middle right) are compensated by the electron beam. Scale bar is 50 nm.

Mentions: Scanning helium ion microscopy (SHIM) and ion milling (performed with the same instrument) has emerged as a tool capable of fabricating graphene devices12 with feature sizes down to ~5 nm3. Commercial SHIMs are now capable of ion milling at the nanoscale using either He+ or Ne+. Moreover, as a direct-fabrication method, He+ milling requires no resists, developer or wash to fabricate features yet can achieve feature sizes comparable to or smaller than EBL. The smaller interaction volume of the helium ion beam with the sample results in reduced proximity effects compared to EBL, and improved sputtering yield in the surface layer1. In our experiment, simple graphene structures consisting of a strip and a pad (Fig. 1) were fabricated using such direct-write lithography1 in a SHIM (see Methods section), with the graphene grounded to the instrument for charge compensation due to loss of secondary electrons. A square (or pad) is milled out leaving only a thin strip connecting the pad to the remaining graphene around the pad. The thin strip acts as a conductor between the surrounding graphene area and the milled pad.


Maskless Lithography and in situ Visualization of Conductivity of Graphene using Helium Ion Microscopy.

Iberi V, Vlassiouk I, Zhang XG, Matola B, Linn A, Joy DC, Rondinone AJ - Sci Rep (2015)

(Left panel) SHIM images of graphene-based pads that have been fabricated using direct-write He+ lithography.(Top left) Nonconducting graphene pad due to insufficient supply of electrons through the thin conducting graphene strip (~10 nm). (Middle left) Onset of slight conduction in graphene pad as the width of the conducting strip is increased to 12 nm. Thermal noise is also evident in the pad. (Bottom left) Fully conducting graphene pad with conducting strip width of 14 nm. (Right panel) SEM images of the exact same structures indicating insufficient electrons in the graphene pads (top and middle right) are compensated by the electron beam. Scale bar is 50 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493665&req=5

f1: (Left panel) SHIM images of graphene-based pads that have been fabricated using direct-write He+ lithography.(Top left) Nonconducting graphene pad due to insufficient supply of electrons through the thin conducting graphene strip (~10 nm). (Middle left) Onset of slight conduction in graphene pad as the width of the conducting strip is increased to 12 nm. Thermal noise is also evident in the pad. (Bottom left) Fully conducting graphene pad with conducting strip width of 14 nm. (Right panel) SEM images of the exact same structures indicating insufficient electrons in the graphene pads (top and middle right) are compensated by the electron beam. Scale bar is 50 nm.
Mentions: Scanning helium ion microscopy (SHIM) and ion milling (performed with the same instrument) has emerged as a tool capable of fabricating graphene devices12 with feature sizes down to ~5 nm3. Commercial SHIMs are now capable of ion milling at the nanoscale using either He+ or Ne+. Moreover, as a direct-fabrication method, He+ milling requires no resists, developer or wash to fabricate features yet can achieve feature sizes comparable to or smaller than EBL. The smaller interaction volume of the helium ion beam with the sample results in reduced proximity effects compared to EBL, and improved sputtering yield in the surface layer1. In our experiment, simple graphene structures consisting of a strip and a pad (Fig. 1) were fabricated using such direct-write lithography1 in a SHIM (see Methods section), with the graphene grounded to the instrument for charge compensation due to loss of secondary electrons. A square (or pad) is milled out leaving only a thin strip connecting the pad to the remaining graphene around the pad. The thin strip acts as a conductor between the surrounding graphene area and the milled pad.

Bottom Line: The remarkable mechanical and electronic properties of graphene make it an ideal candidate for next generation nanoelectronics.With the recent development of commercial-level single-crystal graphene layers, the potential for manufacturing household graphene-based devices has improved, but significant challenges still remain with regards to patterning the graphene into devices.In the case of graphene supported on a substrate, traditional nanofabrication techniques such as e-beam lithography (EBL) are often used in fabricating graphene nanoribbons but the multi-step processes they require can result in contamination of the graphene with resists and solvents.

View Article: PubMed Central - PubMed

Affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.

ABSTRACT
The remarkable mechanical and electronic properties of graphene make it an ideal candidate for next generation nanoelectronics. With the recent development of commercial-level single-crystal graphene layers, the potential for manufacturing household graphene-based devices has improved, but significant challenges still remain with regards to patterning the graphene into devices. In the case of graphene supported on a substrate, traditional nanofabrication techniques such as e-beam lithography (EBL) are often used in fabricating graphene nanoribbons but the multi-step processes they require can result in contamination of the graphene with resists and solvents. In this letter, we report the utility of scanning helium ion lithography for fabricating functional graphene nanoconductors that are supported directly on a silicon dioxide layer, and we measure the minimum feature size achievable due to limitations imposed by thermal fluctuations and ion scattering during the milling process. Further we demonstrate that ion beams, due to their positive charging nature, may be used to observe and test the conductivity of graphene-based nanoelectronic devices in situ.

No MeSH data available.


Related in: MedlinePlus