Limits...
Revelation of graphene-Au for direct write deposition and characterization.

Bhandari S, Deepa M, Joshi AG, Saxena AP, Srivastava AK - Nanoscale Res Lett (2011)

Bottom Line: Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt.Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope.Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Physical Laboratory, Council of Scientific and Industrial Research, Dr, K,S, Krishnan Road, New Delhi, 110 012, India. aks@nplindia.ernet.in.

ABSTRACT
Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt. The as-produced graphene was characterized by X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM). In particular, the HR-TEM demonstrated the layered crystallites of graphene with fringe spacing of about 0.32 nm in individual sheets and the ultrafine facetted structure of about 20 to 50 nm of Au particles in graphene composite. Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope. Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

No MeSH data available.


He ion microscopy. Showing (a) nano-patterning by direct write deposition and (b) distribution of gold particles marked with a set of arrows in graphene.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211841&req=5

Figure 5: He ion microscopy. Showing (a) nano-patterning by direct write deposition and (b) distribution of gold particles marked with a set of arrows in graphene.

Mentions: Nano-patterning by use of a high-resolution microscope is a fast developing method which facilitates in situ examination of the microstructure and direct write of arbitrary patterns on the given nanomaterial. HIM is showing the capability to create smaller structures than possible with other technique [15-17]. In the present work, HIM has been employed to write National Physical Laboratory in Hindi language in Devnagari script in the form of deposited carbon (Figure 5a). Combining a high-brightness gas field ion source with unique sample interaction dynamics, the He ion microscope provides images with unique contrast and complementary information to existing charged particle imaging instruments such as the SEM and TEM. Formed by a single atom at the emitter tip, the He probe can be focused to below 0.35 nm offering the highest recorded resolution for secondary electron images. The small interaction volume between the helium beam and the sample also results in images with stunning surface detail. Besides high-resolution imaging, the collimated beam of He ions can be manipulated for nano-patterning on even two-dimensional nanostructured materials like graphene. The unique combination of sub-nanometer high-resolution surface microscopy and in situ nano-scaled structural buildings elucidates a new field which is so far relatively unexplored in fabrication and process control of fundamentally important nano-objects like graphene. In the present work, the text ("National Physical Laboratory" in Hindi language) was created by deposition of carbon. This pattern, in the form of a bitmap, was opened up in Orion software Carl Zeiss NTS LLC, 1 Corporation Way, Peabody MA 01960, U.S.A. Subsequently, the user defined the size of the overall pattern, and the pixel size was scaled accordingly. The ion dose per pixel was also variable, being set in proportion to the gray level in the bitmap (up to 256 levels). Lettering with gaps down to 7 nm was observed. In this process, the direction of scanning was also user selectable. In another set of experiments, HIM was used to study the distribution of Au in the matrix of graphene (Figure 5b). We have noticed that spherical Au nanoparticles of size in the range of 20 to 50 nm are uniformly distributed in the matrix. A thin layer of graphene on the surface of individual Au nanoparticles is also inferred due to the presence of a glazy contrast on Au surfaces. It is important to mention that there is no deterioration at the boundaries between the matrix and the second phase.


Revelation of graphene-Au for direct write deposition and characterization.

Bhandari S, Deepa M, Joshi AG, Saxena AP, Srivastava AK - Nanoscale Res Lett (2011)

He ion microscopy. Showing (a) nano-patterning by direct write deposition and (b) distribution of gold particles marked with a set of arrows in graphene.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211841&req=5

Figure 5: He ion microscopy. Showing (a) nano-patterning by direct write deposition and (b) distribution of gold particles marked with a set of arrows in graphene.
Mentions: Nano-patterning by use of a high-resolution microscope is a fast developing method which facilitates in situ examination of the microstructure and direct write of arbitrary patterns on the given nanomaterial. HIM is showing the capability to create smaller structures than possible with other technique [15-17]. In the present work, HIM has been employed to write National Physical Laboratory in Hindi language in Devnagari script in the form of deposited carbon (Figure 5a). Combining a high-brightness gas field ion source with unique sample interaction dynamics, the He ion microscope provides images with unique contrast and complementary information to existing charged particle imaging instruments such as the SEM and TEM. Formed by a single atom at the emitter tip, the He probe can be focused to below 0.35 nm offering the highest recorded resolution for secondary electron images. The small interaction volume between the helium beam and the sample also results in images with stunning surface detail. Besides high-resolution imaging, the collimated beam of He ions can be manipulated for nano-patterning on even two-dimensional nanostructured materials like graphene. The unique combination of sub-nanometer high-resolution surface microscopy and in situ nano-scaled structural buildings elucidates a new field which is so far relatively unexplored in fabrication and process control of fundamentally important nano-objects like graphene. In the present work, the text ("National Physical Laboratory" in Hindi language) was created by deposition of carbon. This pattern, in the form of a bitmap, was opened up in Orion software Carl Zeiss NTS LLC, 1 Corporation Way, Peabody MA 01960, U.S.A. Subsequently, the user defined the size of the overall pattern, and the pixel size was scaled accordingly. The ion dose per pixel was also variable, being set in proportion to the gray level in the bitmap (up to 256 levels). Lettering with gaps down to 7 nm was observed. In this process, the direction of scanning was also user selectable. In another set of experiments, HIM was used to study the distribution of Au in the matrix of graphene (Figure 5b). We have noticed that spherical Au nanoparticles of size in the range of 20 to 50 nm are uniformly distributed in the matrix. A thin layer of graphene on the surface of individual Au nanoparticles is also inferred due to the presence of a glazy contrast on Au surfaces. It is important to mention that there is no deterioration at the boundaries between the matrix and the second phase.

Bottom Line: Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt.Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope.Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Physical Laboratory, Council of Scientific and Industrial Research, Dr, K,S, Krishnan Road, New Delhi, 110 012, India. aks@nplindia.ernet.in.

ABSTRACT
Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt. The as-produced graphene was characterized by X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM). In particular, the HR-TEM demonstrated the layered crystallites of graphene with fringe spacing of about 0.32 nm in individual sheets and the ultrafine facetted structure of about 20 to 50 nm of Au particles in graphene composite. Scanning helium ion microscopy (HIM) technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope. Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

No MeSH data available.