Transport properties of graphene with one-dimensional charge defects

Ferreira, Aires; Xu, Xiangfan; Chang-Lin, Tan; Bae, Sukang; Peres, N. M. R.; Hong, Byung-Woo; Özyilmaz, Barbaros; Neto, A. H. Castro

doi:10.1209/0295-5075/94/28003

Cited by 68 publications

(48 citation statements)

References 23 publications

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“…(7), (9), (11) These results are at first rather surprising, since CVD graphene has additional solvent residues, Hence, the limiting spin dephasing mechanisms at RT remain EY type and DP type in CVD SLG and CVD BLG, respectively. (30) structural differences, (18) in particular grain boundaries (17) and nanoripples (19) when compared to exfoliated graphene. Also, Cu-CVD growth typically requires high temperatures of 1000 -1050°C.…”

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confidence: 99%

Toward Wafer Scale Fabrication of Graphene Based Spin Valve Devices

et al. 2011

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We demonstrate injection, transport and detection of spins in spin valve arrays patterned in both copper based chemical vapor deposition (Cu-CVD) synthesized wafer scale single layer (SLG) and bilayer graphene (BLG). We observe spin relaxation times comparable to those reported for exfoliated graphene samples demonstrating that CVD specific structural differences such as nanoripples and grain boundaries do not limit spin transport in the present samples. Our observations make Cu-CVD graphene a promising material of choice for large scale spintronic applications. KEYWORDS Spin transport, Hanle precession, graphene, CVD growth, rippleHigh charge mobility, (1) small spin-orbit coupling, (2) negligible hyperfine interaction, (3) the electric field effect (4) and last but not least the ability to sustain large current densities (5) make graphene an exceptional material for spintronic applications. The demonstration of micrometer long spin relaxation length in exfoliated SLG and BLG even at room temperature (RT) (6)-(12) and spin relaxation times in the order of nanoseconds (11)-(12) may pave the way to realize several of the recently proposed spin based device concepts. (13)- (15) However, for realistic device applications it remains to be seen, if such impressive spin transport properties can also be achieved in wafer scale CVD graphene. Equally important, spin transport studies based on micromechanically exfoliated graphene sheets are often too slow for the quick exploration of the basic spin properties of graphene and for testing potential device architectures. The recent progress in the Cu-based CVD growth of graphene has a strong impact on charge based graphene device applications. (16) However, CVD graphene has a large number of structural differences when compared to exfoliated graphene such as grain boundaries, (17) defects like pentagons, heptagons, octagons, vacancies, 1D line charges (18) and in the case of bilayer graphene possibly interlayer stacking faults. (19)-(20) In addition, the current growth and transfer process introduces residual catalysts, wrinkles, quasi-periodic nanoripple arrays and new classes of organic residues. (19) Despite all of these defects, charge mobilities in CVD graphene field effect transistors (FETs) have been comparable to what has been reported for most exfoliated graphene FETs on Si/SiO 2 substrates. (21) 3 Whether this synthesis route will also play an important role for spin transport studies and large scale spin-based device applications depends on how the same defects affect the spin relaxation times.In this Letter, we demonstrate spin transport in Cu-CVD grown SLG and BLG transferred onto conventional Si/SiO 2 substrates and discuss the role of nano-ripples, a ubiquitous surface structure of Cu-CVD graphene (19) . The growth and transfer of large-scale Cu-CVD graphene are the same as in Ref.(17). By controlling the post-growth annealing time of CVD graphene, we can obtain films with SLG coverage up to 95% or additional BLG coverage up to 40%. The latter...

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Toward Wafer Scale Fabrication of Graphene Based Spin Valve Devices

et al. 2011

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“…An expression for the scattering potential can be obtained within the semiclassical TF approximation describing the screening of an extended charged line defect by the surrounding electron gas, 12,15 …”

Section: Resultsmentioning

confidence: 99%

“…The TF potential (4) was used for semiclassical Boltzmann and quantum-mechanical Kubo calculations of the conductivity of CVD graphene. 12,15 It is therefore important to find whether this potential provides a reliable approximation for the numerically exact quantummechanical self-consistent potential. A comparison between the TF potential (4) and the self-consistent potential calculated Fig.…”

Section: Resultsmentioning

confidence: 99%

“…[3][4][5] Significant evidence has accumulated by now that the GBs strongly affect electrical transport [6][7][8][9][10][11] and represent the limiting scattering mechanism of the electronic mobility in CVDgrown graphene. [12][13][14][15] This provides a strong motivation for investigation of morphological, electronic, and spin properties of GBs. A number of studies have been recently reported addressing the band structure, [16][17][18][19][20] spin polarization, 16,17,21,22 electron transport and scattering 12,13,20 in GBs.…”

Section: Introductionmentioning

confidence: 99%

“…[12][13][14][15] This provides a strong motivation for investigation of morphological, electronic, and spin properties of GBs. A number of studies have been recently reported addressing the band structure, [16][17][18][19][20] spin polarization, 16,17,21,22 electron transport and scattering 12,13,20 in GBs. However, all these studies were limited to the case of electrically neutral graphene, and very little is presently known on how the electronic and transport properties of GBs are modified at nonzero electron densities (i.e., away from the Dirac point).…”

Section: Introductionmentioning

confidence: 99%

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Electron interaction, charging, and screening at grain boundaries in graphene

Ihnatsenka

Zozoulenko

2013

Phys. Rev. B

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Electronic, transport, and spin properties of grain boundaries (GBs) are investigated in electrostatically doped graphene at finite electron densities within the Hartree and Hubbard approximations. We demonstrate that depending on the character of the GBs, the states residing on them can have a metallic character with a zero group velocity or can be fully populated losing the ability to carry a current. These states show qualitatively different features in charge accumulation and spin polarization. We also demonstrate that the semiclassical Thomas-Fermi approach provides a satisfactory approximation to the calculated self-consistent potential. The conductance of GBs is reduced due to enhanced backscattering from this potential.

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