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Lateral homogeneity of the electronic properties in pristine and ion-irradiated graphene probed by scanning capacitance spectroscopy.

Giannazzo F, Sonde S, Rimini E, Raineri V - Nanoscale Res Lett (2011)

Bottom Line: In this article, a scanning probe method based on nanoscale capacitance measurements was used to investigate the lateral homogeneity of the electron mean free path both in pristine and ion-irradiated graphene.The local variations in the electronic transport properties were explained taking into account the scattering of electrons by charged impurities and point defects (vacancies).The local density of the charged impurities and vacancies were determined for different irradiated ion fluences.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNR-IMM, Strada VIII, 5, Zona Industriale, 95121, Catania, Italy. filippo.giannazzo@imm.cnr.it.

ABSTRACT
In this article, a scanning probe method based on nanoscale capacitance measurements was used to investigate the lateral homogeneity of the electron mean free path both in pristine and ion-irradiated graphene. The local variations in the electronic transport properties were explained taking into account the scattering of electrons by charged impurities and point defects (vacancies). Electron mean free path is mainly limited by charged impurities in unirradiated graphene, whereas an important role is played by lattice vacancies after irradiation. The local density of the charged impurities and vacancies were determined for different irradiated ion fluences.

No MeSH data available.


Schematic representation of the scanning capacitance spectroscopy setup.
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Figure 1: Schematic representation of the scanning capacitance spectroscopy setup.

Mentions: Scanning capacitance spectroscopy (SCS) was performed at room temperature using a DI3100 AFM by Veeco equipped with Nanoscope V electronics and with the scanning capacitance microscopy (SCM) head. SCS is an extension of the conventional SCM [16-19]. In SCS, the conductive AFM tip is placed on a discrete array of positions, lifting the tip by 20 nm at every interval. This "step and measure" approach eliminates the lateral (shear) force usually present when tip is scanned on a surface. Moreover, the vertical contact force can be suitably minimized to get a good electrical contact to the graphene layers while avoiding damage at the same time. A modulating bias ΔV = Vg/2(1 + sin(ωt)), with amplitude Vg in the range from -1.2 to 1.2 V and frequency ω = 100 kHz, was applied between the Si n+ backgate and the nanometric contact on graphene represented by a Pt-coated Si tip (see schematic in Figure 1). The ultra-high-sensitive (10-21 F/Hz1/2) capacitance sensor connected to the conductive AFM tip measures, through a lock-in system, the capacitance variation ΔC induced by the modulating bias.


Lateral homogeneity of the electronic properties in pristine and ion-irradiated graphene probed by scanning capacitance spectroscopy.

Giannazzo F, Sonde S, Rimini E, Raineri V - Nanoscale Res Lett (2011)

Schematic representation of the scanning capacitance spectroscopy setup.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211153&req=5

Figure 1: Schematic representation of the scanning capacitance spectroscopy setup.
Mentions: Scanning capacitance spectroscopy (SCS) was performed at room temperature using a DI3100 AFM by Veeco equipped with Nanoscope V electronics and with the scanning capacitance microscopy (SCM) head. SCS is an extension of the conventional SCM [16-19]. In SCS, the conductive AFM tip is placed on a discrete array of positions, lifting the tip by 20 nm at every interval. This "step and measure" approach eliminates the lateral (shear) force usually present when tip is scanned on a surface. Moreover, the vertical contact force can be suitably minimized to get a good electrical contact to the graphene layers while avoiding damage at the same time. A modulating bias ΔV = Vg/2(1 + sin(ωt)), with amplitude Vg in the range from -1.2 to 1.2 V and frequency ω = 100 kHz, was applied between the Si n+ backgate and the nanometric contact on graphene represented by a Pt-coated Si tip (see schematic in Figure 1). The ultra-high-sensitive (10-21 F/Hz1/2) capacitance sensor connected to the conductive AFM tip measures, through a lock-in system, the capacitance variation ΔC induced by the modulating bias.

Bottom Line: In this article, a scanning probe method based on nanoscale capacitance measurements was used to investigate the lateral homogeneity of the electron mean free path both in pristine and ion-irradiated graphene.The local variations in the electronic transport properties were explained taking into account the scattering of electrons by charged impurities and point defects (vacancies).The local density of the charged impurities and vacancies were determined for different irradiated ion fluences.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNR-IMM, Strada VIII, 5, Zona Industriale, 95121, Catania, Italy. filippo.giannazzo@imm.cnr.it.

ABSTRACT
In this article, a scanning probe method based on nanoscale capacitance measurements was used to investigate the lateral homogeneity of the electron mean free path both in pristine and ion-irradiated graphene. The local variations in the electronic transport properties were explained taking into account the scattering of electrons by charged impurities and point defects (vacancies). Electron mean free path is mainly limited by charged impurities in unirradiated graphene, whereas an important role is played by lattice vacancies after irradiation. The local density of the charged impurities and vacancies were determined for different irradiated ion fluences.

No MeSH data available.