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Theoretical study of the role of metallic contacts in probing transport features of pure and defected graphene nanoribbons.

La Magna A, Deretzis I - Nanoscale Res Lett (2011)

Bottom Line: We theoretically characterize the formation of metal-graphene junctions as well as the effects of backscattering due to the presence of vacancies and impurities.Our results evidence that disorder can infer significant alterations on the conduction process, giving rise to mobility gaps in the conductance distribution.Moreover, we show the importance of metal-graphene coupling that gives rise to doping-related phenomena and a degradation of conductance quantization characteristics.

View Article: PubMed Central - HTML - PubMed

Affiliation: 1CNR IMM, Z,I, VIII Strada 5, 95121 Catania, Italy. antonino.lamagna@imm.cnr.it.

ABSTRACT
Understanding the roles of disorder and metal/graphene interface on the electronic and transport properties of graphene-based systems is crucial for a consistent analysis of the data deriving from experimental measurements. The present work is devoted to the detailed study of graphene nanoribbon systems by means of self-consistent quantum transport calculations. The computational formalism is based on a coupled Schrödinger/Poisson approach that respects both chemistry and electrostatics, applied to pure/defected graphene nanoribbons (ideally or end-contacted by various fcc metals). We theoretically characterize the formation of metal-graphene junctions as well as the effects of backscattering due to the presence of vacancies and impurities. Our results evidence that disorder can infer significant alterations on the conduction process, giving rise to mobility gaps in the conductance distribution. Moreover, we show the importance of metal-graphene coupling that gives rise to doping-related phenomena and a degradation of conductance quantization characteristics.

No MeSH data available.


Average conductance for nitrogen-doped and vacancy-damaged AGNRs. Average conductance <g> as a function of the energy E for a nitrogen-doped Na = 45 AGNR (solid line), nitrogen-doped Na = 47 AGNR (dashed line), and vacancy-damaged Na = 47 AGNR (point) with fixed length: L ≈ 0.21 μm. Plotted values represent statistical averages over more of 500 equivalent replicas of the system. Charge neutrality points of pure and defected systems are aligned at E = 0 eV in the figure.
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Figure 2: Average conductance for nitrogen-doped and vacancy-damaged AGNRs. Average conductance <g> as a function of the energy E for a nitrogen-doped Na = 45 AGNR (solid line), nitrogen-doped Na = 47 AGNR (dashed line), and vacancy-damaged Na = 47 AGNR (point) with fixed length: L ≈ 0.21 μm. Plotted values represent statistical averages over more of 500 equivalent replicas of the system. Charge neutrality points of pure and defected systems are aligned at E = 0 eV in the figure.

Mentions: A qualitatively similar behavior is shown by the vacancy-damaged and nitrogen-doped semimetallic Na = 47 AGNR (see Figure 2). In the vacancy-damaged case, a large mobility gap appears in the negative energies (hole band) region [9] due to the strong backscattering of the defects. However, apart from the intensity of the scattering, vacancy-defected systems have a p impurity-like behavior.


Theoretical study of the role of metallic contacts in probing transport features of pure and defected graphene nanoribbons.

La Magna A, Deretzis I - Nanoscale Res Lett (2011)

Average conductance for nitrogen-doped and vacancy-damaged AGNRs. Average conductance <g> as a function of the energy E for a nitrogen-doped Na = 45 AGNR (solid line), nitrogen-doped Na = 47 AGNR (dashed line), and vacancy-damaged Na = 47 AGNR (point) with fixed length: L ≈ 0.21 μm. Plotted values represent statistical averages over more of 500 equivalent replicas of the system. Charge neutrality points of pure and defected systems are aligned at E = 0 eV in the figure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211293&req=5

Figure 2: Average conductance for nitrogen-doped and vacancy-damaged AGNRs. Average conductance <g> as a function of the energy E for a nitrogen-doped Na = 45 AGNR (solid line), nitrogen-doped Na = 47 AGNR (dashed line), and vacancy-damaged Na = 47 AGNR (point) with fixed length: L ≈ 0.21 μm. Plotted values represent statistical averages over more of 500 equivalent replicas of the system. Charge neutrality points of pure and defected systems are aligned at E = 0 eV in the figure.
Mentions: A qualitatively similar behavior is shown by the vacancy-damaged and nitrogen-doped semimetallic Na = 47 AGNR (see Figure 2). In the vacancy-damaged case, a large mobility gap appears in the negative energies (hole band) region [9] due to the strong backscattering of the defects. However, apart from the intensity of the scattering, vacancy-defected systems have a p impurity-like behavior.

Bottom Line: We theoretically characterize the formation of metal-graphene junctions as well as the effects of backscattering due to the presence of vacancies and impurities.Our results evidence that disorder can infer significant alterations on the conduction process, giving rise to mobility gaps in the conductance distribution.Moreover, we show the importance of metal-graphene coupling that gives rise to doping-related phenomena and a degradation of conductance quantization characteristics.

View Article: PubMed Central - HTML - PubMed

Affiliation: 1CNR IMM, Z,I, VIII Strada 5, 95121 Catania, Italy. antonino.lamagna@imm.cnr.it.

ABSTRACT
Understanding the roles of disorder and metal/graphene interface on the electronic and transport properties of graphene-based systems is crucial for a consistent analysis of the data deriving from experimental measurements. The present work is devoted to the detailed study of graphene nanoribbon systems by means of self-consistent quantum transport calculations. The computational formalism is based on a coupled Schrödinger/Poisson approach that respects both chemistry and electrostatics, applied to pure/defected graphene nanoribbons (ideally or end-contacted by various fcc metals). We theoretically characterize the formation of metal-graphene junctions as well as the effects of backscattering due to the presence of vacancies and impurities. Our results evidence that disorder can infer significant alterations on the conduction process, giving rise to mobility gaps in the conductance distribution. Moreover, we show the importance of metal-graphene coupling that gives rise to doping-related phenomena and a degradation of conductance quantization characteristics.

No MeSH data available.