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Toward Two-Dimensional All-Carbon Heterostructures via Ion Beam Patterning of Single-Layer Graphene.

Kotakoski J, Brand C, Lilach Y, Cheshnovsky O, Mangler C, Arndt M, Meyer JC - Nano Lett. (2015)

Bottom Line: The atomic structure of the disordered regions is confirmed with atomic-resolution scanning transmission electron microscopy images.With just one processing step, three types of structures can be defined within a graphene layer: chemically inert graphene, chemically active amorphous 2D carbon, and empty areas.This, along with the changes in properties, gives promise that FIB patterning of graphene will open the way for creating all-carbon heterostructures to be used in fields ranging from nanoelectronics and chemical sensing to composite materials.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Physics, PNM and ‡Faculty of Physics, VCQ, QuNaBioS, University of Vienna , Boltzmanngasse 5, A-1090 Vienna, Austria.

ABSTRACT
Graphene has many claims to fame: it is the thinnest possible membrane, it has unique electronic and excellent mechanical properties, and it provides the perfect model structure for studying materials science at the atomic level. However, for many practical studies and applications the ordered hexagon arrangement of carbon atoms in graphene is not directly suitable. Here, we show that the atoms can be locally either removed or rearranged into a random pattern of polygons using a focused ion beam (FIB). The atomic structure of the disordered regions is confirmed with atomic-resolution scanning transmission electron microscopy images. These structural modifications can be made on macroscopic scales with a spatial resolution determined only by the size of the ion beam. With just one processing step, three types of structures can be defined within a graphene layer: chemically inert graphene, chemically active amorphous 2D carbon, and empty areas. This, along with the changes in properties, gives promise that FIB patterning of graphene will open the way for creating all-carbon heterostructures to be used in fields ranging from nanoelectronics and chemical sensing to composite materials.

No MeSH data available.


Related in: MedlinePlus

Chemical etching of the amorphous pattern. (a) STEM-MAADFclose-up image of a patterned area of the sample before and (b) afteran exposure of about 1 h to a parallel electron beam while air wasleaked to the objective area of the microscope column (pressure increasefrom ca. 5.3 × 10–9 to 1.1 × 10–6 mbar). The approximate area exposed to the beam corresponds to thedarkened circular shape seen in panel (b). Partial overlay on theleft-hand-side of panel (a) highlights the structure of the pattern(“ml+cont” corresponds to nonirradiated graphene andcontamination, whereas “am+cont” refers to amorphizedareas). Circles with solid and dashed lines mark the same hole andmetal contamination, respectively, in both images to ease the comparison.A higher magnification of the area marked with a rectangle in panel(b) is shown in panel (c) to ease distinguishing holes and clean graphenefrom each other.
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fig3: Chemical etching of the amorphous pattern. (a) STEM-MAADFclose-up image of a patterned area of the sample before and (b) afteran exposure of about 1 h to a parallel electron beam while air wasleaked to the objective area of the microscope column (pressure increasefrom ca. 5.3 × 10–9 to 1.1 × 10–6 mbar). The approximate area exposed to the beam corresponds to thedarkened circular shape seen in panel (b). Partial overlay on theleft-hand-side of panel (a) highlights the structure of the pattern(“ml+cont” corresponds to nonirradiated graphene andcontamination, whereas “am+cont” refers to amorphizedareas). Circles with solid and dashed lines mark the same hole andmetal contamination, respectively, in both images to ease the comparison.A higher magnification of the area marked with a rectangle in panel(b) is shown in panel (c) to ease distinguishing holes and clean graphenefrom each other.

Mentions: The ultrahigh vacuumcolumn of the microscope reduces chemical etching to practically zero,simplifying the analysis of dynamical processes. However, at the sametime all beneficial chemical reactions due to water (and other) moleculescracked by the imaging electrons, which could reduce the hydrocarboncontamination, are also prevented. To test both how the contaminationis bound to the graphene and how amorphization affects the chemicalinertness of graphene, we let air into the microscope column afterinitial imaging by opening a leak valve. We exposed the structureto a parallel electron beam while increasing the pressure in the objectivefrom 5.3 × 10–9 to 1.1 × 10–6 mbar over an hour. The results of this treatment are shown in Figure 3. The contaminationdecreased dramatically and several clean areas appeared in the nonirradiatedarea of the sample, whereas holes grew in the irradiated areas. Thisdemonstrates that controlled amorphization of graphene will activateit chemically. Because we were able to clean parts of the contamination,it cannot be covalently bound to the sample. Therefore, one possibleway to overcome the contamination problem could be high-temperaturevacuum annealing, which can be expected to remove most of the floatinghydrocarbons.


Toward Two-Dimensional All-Carbon Heterostructures via Ion Beam Patterning of Single-Layer Graphene.

Kotakoski J, Brand C, Lilach Y, Cheshnovsky O, Mangler C, Arndt M, Meyer JC - Nano Lett. (2015)

Chemical etching of the amorphous pattern. (a) STEM-MAADFclose-up image of a patterned area of the sample before and (b) afteran exposure of about 1 h to a parallel electron beam while air wasleaked to the objective area of the microscope column (pressure increasefrom ca. 5.3 × 10–9 to 1.1 × 10–6 mbar). The approximate area exposed to the beam corresponds to thedarkened circular shape seen in panel (b). Partial overlay on theleft-hand-side of panel (a) highlights the structure of the pattern(“ml+cont” corresponds to nonirradiated graphene andcontamination, whereas “am+cont” refers to amorphizedareas). Circles with solid and dashed lines mark the same hole andmetal contamination, respectively, in both images to ease the comparison.A higher magnification of the area marked with a rectangle in panel(b) is shown in panel (c) to ease distinguishing holes and clean graphenefrom each other.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4566131&req=5

fig3: Chemical etching of the amorphous pattern. (a) STEM-MAADFclose-up image of a patterned area of the sample before and (b) afteran exposure of about 1 h to a parallel electron beam while air wasleaked to the objective area of the microscope column (pressure increasefrom ca. 5.3 × 10–9 to 1.1 × 10–6 mbar). The approximate area exposed to the beam corresponds to thedarkened circular shape seen in panel (b). Partial overlay on theleft-hand-side of panel (a) highlights the structure of the pattern(“ml+cont” corresponds to nonirradiated graphene andcontamination, whereas “am+cont” refers to amorphizedareas). Circles with solid and dashed lines mark the same hole andmetal contamination, respectively, in both images to ease the comparison.A higher magnification of the area marked with a rectangle in panel(b) is shown in panel (c) to ease distinguishing holes and clean graphenefrom each other.
Mentions: The ultrahigh vacuumcolumn of the microscope reduces chemical etching to practically zero,simplifying the analysis of dynamical processes. However, at the sametime all beneficial chemical reactions due to water (and other) moleculescracked by the imaging electrons, which could reduce the hydrocarboncontamination, are also prevented. To test both how the contaminationis bound to the graphene and how amorphization affects the chemicalinertness of graphene, we let air into the microscope column afterinitial imaging by opening a leak valve. We exposed the structureto a parallel electron beam while increasing the pressure in the objectivefrom 5.3 × 10–9 to 1.1 × 10–6 mbar over an hour. The results of this treatment are shown in Figure 3. The contaminationdecreased dramatically and several clean areas appeared in the nonirradiatedarea of the sample, whereas holes grew in the irradiated areas. Thisdemonstrates that controlled amorphization of graphene will activateit chemically. Because we were able to clean parts of the contamination,it cannot be covalently bound to the sample. Therefore, one possibleway to overcome the contamination problem could be high-temperaturevacuum annealing, which can be expected to remove most of the floatinghydrocarbons.

Bottom Line: The atomic structure of the disordered regions is confirmed with atomic-resolution scanning transmission electron microscopy images.With just one processing step, three types of structures can be defined within a graphene layer: chemically inert graphene, chemically active amorphous 2D carbon, and empty areas.This, along with the changes in properties, gives promise that FIB patterning of graphene will open the way for creating all-carbon heterostructures to be used in fields ranging from nanoelectronics and chemical sensing to composite materials.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Physics, PNM and ‡Faculty of Physics, VCQ, QuNaBioS, University of Vienna , Boltzmanngasse 5, A-1090 Vienna, Austria.

ABSTRACT
Graphene has many claims to fame: it is the thinnest possible membrane, it has unique electronic and excellent mechanical properties, and it provides the perfect model structure for studying materials science at the atomic level. However, for many practical studies and applications the ordered hexagon arrangement of carbon atoms in graphene is not directly suitable. Here, we show that the atoms can be locally either removed or rearranged into a random pattern of polygons using a focused ion beam (FIB). The atomic structure of the disordered regions is confirmed with atomic-resolution scanning transmission electron microscopy images. These structural modifications can be made on macroscopic scales with a spatial resolution determined only by the size of the ion beam. With just one processing step, three types of structures can be defined within a graphene layer: chemically inert graphene, chemically active amorphous 2D carbon, and empty areas. This, along with the changes in properties, gives promise that FIB patterning of graphene will open the way for creating all-carbon heterostructures to be used in fields ranging from nanoelectronics and chemical sensing to composite materials.

No MeSH data available.


Related in: MedlinePlus