Limits...
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 with longer connecting strips that have been fabricated using direct-write He+ lithography.Areas (i) and (ii) are isolated graphene regions within the device. (Top left) Nonconducting graphene pad due to insufficient supply of electrons through the thin conducting graphene strip (~12 nm). (Middle left) Onset of slight conduction in graphene pad as the width of the conducting strip is increased to 18 nm. Thermal noise is also evident in the pad. (Bottom left) Fully conducting graphene pad with conducting strip width of 20 nm. (Right panel) SEM images of the exact same structures indicating that insufficient electrons in the graphene pads (top and middle) are compensated by the electron beam. Scale bar is 50 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4493665&req=5

f2: (Left panel) SHIM images of graphene-based pads with longer connecting strips that have been fabricated using direct-write He+ lithography.Areas (i) and (ii) are isolated graphene regions within the device. (Top left) Nonconducting graphene pad due to insufficient supply of electrons through the thin conducting graphene strip (~12 nm). (Middle left) Onset of slight conduction in graphene pad as the width of the conducting strip is increased to 18 nm. Thermal noise is also evident in the pad. (Bottom left) Fully conducting graphene pad with conducting strip width of 20 nm. (Right panel) SEM images of the exact same structures indicating that insufficient electrons in the graphene pads (top and middle) are compensated by the electron beam. Scale bar is 50 nm.

Mentions: A second class of graphene devices was explored in order to investigate the impact of the length of the conducting strip. These devices were fabricated to include two smaller regions (i and ii) that have been completely electrically isolated in order create conducting-insulating composites. Similar to Fig. 1, the corresponding SEM images have been used for direct comparison (Fig. 2, right panel). Beam damage resulting from prolonged exposure of the graphene device to the electron beam is also evident. In Fig. 2a, the width of the connecting bridge is ~12 nm but due to the increased length and possibly the effect of vibrations, it appears to be nonconducting as was the device in Fig. 1a. Figure 2(b–c) shows the progression of the device towards conductivity (beginning at ~18 nm) while the sub regions i and ii constantly remain insulating. Similar to Fig. 1b, image noise just within the pad indicate thermal fluctuations in the device and suggest that the electrical properties of the strip strongly depend on its width. Avouris and co-workers11 studied the effect of decreasing the width of graphene nanoribbons fabricated with EBL on the electrical properties of field-effect transistor devices. The minimum graphene nanoribbon width achieved with their method was 20 nm. Their results showed that as the width of the nanoribbon decreased, its maximum resistivity increased at room temperature. This effect was attributed to scattering which occurred at the rough boundaries of the nanoribbon, and imperfections at the atomic scale. In our experiment, a minimum width of 10 nm for the shorter strip and 12 nm for the longer strip show the same effect on the conductivity of the graphene pads.


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 with longer connecting strips that have been fabricated using direct-write He+ lithography.Areas (i) and (ii) are isolated graphene regions within the device. (Top left) Nonconducting graphene pad due to insufficient supply of electrons through the thin conducting graphene strip (~12 nm). (Middle left) Onset of slight conduction in graphene pad as the width of the conducting strip is increased to 18 nm. Thermal noise is also evident in the pad. (Bottom left) Fully conducting graphene pad with conducting strip width of 20 nm. (Right panel) SEM images of the exact same structures indicating that insufficient electrons in the graphene pads (top and middle) 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

f2: (Left panel) SHIM images of graphene-based pads with longer connecting strips that have been fabricated using direct-write He+ lithography.Areas (i) and (ii) are isolated graphene regions within the device. (Top left) Nonconducting graphene pad due to insufficient supply of electrons through the thin conducting graphene strip (~12 nm). (Middle left) Onset of slight conduction in graphene pad as the width of the conducting strip is increased to 18 nm. Thermal noise is also evident in the pad. (Bottom left) Fully conducting graphene pad with conducting strip width of 20 nm. (Right panel) SEM images of the exact same structures indicating that insufficient electrons in the graphene pads (top and middle) are compensated by the electron beam. Scale bar is 50 nm.
Mentions: A second class of graphene devices was explored in order to investigate the impact of the length of the conducting strip. These devices were fabricated to include two smaller regions (i and ii) that have been completely electrically isolated in order create conducting-insulating composites. Similar to Fig. 1, the corresponding SEM images have been used for direct comparison (Fig. 2, right panel). Beam damage resulting from prolonged exposure of the graphene device to the electron beam is also evident. In Fig. 2a, the width of the connecting bridge is ~12 nm but due to the increased length and possibly the effect of vibrations, it appears to be nonconducting as was the device in Fig. 1a. Figure 2(b–c) shows the progression of the device towards conductivity (beginning at ~18 nm) while the sub regions i and ii constantly remain insulating. Similar to Fig. 1b, image noise just within the pad indicate thermal fluctuations in the device and suggest that the electrical properties of the strip strongly depend on its width. Avouris and co-workers11 studied the effect of decreasing the width of graphene nanoribbons fabricated with EBL on the electrical properties of field-effect transistor devices. The minimum graphene nanoribbon width achieved with their method was 20 nm. Their results showed that as the width of the nanoribbon decreased, its maximum resistivity increased at room temperature. This effect was attributed to scattering which occurred at the rough boundaries of the nanoribbon, and imperfections at the atomic scale. In our experiment, a minimum width of 10 nm for the shorter strip and 12 nm for the longer strip show the same effect on the conductivity of the graphene pads.

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