p-type doping of graphene with F4-TCNQ

Pinto, H.; Jones, R.; Goss, Jonathan P.; Briddon, P.R.

doi:10.1088/0953-8984/21/40/402001

Cited by 125 publications

(134 citation statements)

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“…Since the calculated C-C-C and C-C-H angles of the molecule are identical and equal to 120°, we conclude that benzene reorients itself in a planar manner above the graphene. This orientation has also been noted for F4-TCNQ (Pinto et al, 2009) which indicates similar adsorption mechanism for organic molecules on graphene. Adsorbed-graphene sheet, on the other side, has been found to have a C-C bond length of 1.41 Å and a C-C-C angle of 120°.…”

Section: Benzene-adsorbed Graphenesupporting

confidence: 75%

“…Additionally, the high conductivity of graphene even in low charge density is another reason for being a highly-sensitive sensor. Having established the importance of pristine graphene in many potential applications, the adsorption of single atoms (Chan et al, 2008;Farjam & Rafii-Tabar, 2009;Han et al, 2007;Hao et al, 2006;Li et al, 2008;Mao et al, 2008;Medeiros, 2010;Yang, 2009) and molecules (Duplock et al, 2004;Elias et al, 2009;Giannozzi et al, 2003;Ito et al, 2008;Leenaerts et al, 2008Leenaerts et al, , 2009Nakamura et al, 2008;Novoselov et al, 2004;Pinto et al, 2009;Sanyal et al, 2009;Schedin et al, 2007;Wehling et al, 2008;Y.-H. Zhang, 2010) on the bare graphene surface has been the subject for different theoretical and experimental investigations due to their promising applications in nanoscale electronics, bioelectronics, gas sensors, and hydrogen storage devices. Among these adsorbates, hydrogen has been considered as one of the most interesting and fantastic candidates.…”

Section: Introductionmentioning

confidence: 99%

“…Their theoretical results indicate that the NO 2 adsorbates induce a relatively strong doping comparing to the NO molecule. Within the framework of the local density approximation of the density functional theory, Pinto et al (Pinto et al, 2009) have investigated the chemisorption of tetrafluorotetracyanoquinodimethane (F4-TCNQ) molecule on pristine graphene by means of the electronic properties. It was reported that the F4-TCNQ molecule acts like a p-type dopant for graphene with an approximately charge of 0.3 e/molecule being transferred from the highest occupied molecular orbital (HOMO) of graphene to the lowest unoccupied molecular orbital (LUMO) of the molecule.…”

Section: Introductionmentioning

confidence: 99%

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Structural and Electronic Properties of Graphene upon Molecular Adsorption: DFT Comparative Analysis

AlZahrani¹

2011

Graphene Simulation

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Section: Benzene-adsorbed Graphenesupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural and Electronic Properties of Graphene upon Molecular Adsorption: DFT Comparative Analysis

AlZahrani¹

2011

Graphene Simulation

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“…It has a very high electron affinity (i.e., E ea = 5.24 eV) and has been used successfully as a state of the art p-type dopant in organic light emitting diodes 20,[26][27][28] , carbon nanotubes [29][30][31] and on other materials 32,33 . Recently, the existence of a p-doping effect of F4-TCNQ on graphene has been suggested theoretically 34 and experimentally 25 .…”

Section: Introductionmentioning

confidence: 99%

Charge neutrality and band-gap tuning of epitaxial graphene on SiC by molecular doping

et al. 2010

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Epitaxial graphene on SiC(0001) suffers from strong intrinsic n-type doping. We demonstrate that the excess negative charge can be fully compensated by non-covalently functionalizing graphene with the strong electron acceptor tetrafluorotetracyanoquinodimethane (F4-TCNQ). Charge neutrality can be reached in monolayer graphene as shown in electron dispersion spectra from angular resolved photoemission spectroscopy (ARPES). In bilayer graphene the band gap that originates from the SiC/graphene interface dipole increases with increasing F4-TCNQ deposition and, as a consequence of the molecular doping, the Fermi level is shifted into the band gap. The reduction of the charge carrier density upon molecular deposition is quantified using electronic Fermi surfaces and Raman spectroscopy. The structural and electronic characteristics of the graphene/F4-TCNQ charge transfer complex are investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The doping effect on graphene is preserved in air and is temperature resistant up to 200• C. Furthermore, graphene non-covalent functionalization with F4-TCNQ can be implemented not only via evaporation in ultra-high vacuum but also by wet chemistry.

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“…1b, inset) with typical aspect ratio (L/W) of about 2 and shortest length exceeding 2 µm using Ar plasma at a pressure of ~6.7 Pa (5 x 10 -2 Torr). Molecular charge transfer doping was done by thermal evaporation of ~10 nm of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane organic molecules (SynQuest Labs) on top of the fabricated samples 22,33 .Measurement Thermopower measurement was done using Stanford Research Systems SR830Lock in amplifiers and a commercial cryostat equipped with 9 T superconducting magnet. Low frequency ac (ω < 17 Hz) heater currents was applied to the sample and the resultant 2ω thermoelectric voltage ΔV between two ends of thermisters (see Fig.…”

mentioning

confidence: 99%

Ambipolar Surface State Thermoelectric Power of Topological Insulator Bi₂Se₃

et al. 2014

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We measure gate-tuned thermoelectric power of mechanically exfoliated Bi 2 Se 3 thin films in the topological insulator regime. The sign of the thermoelectric power changes across the charge neutrality point as the majority carrier type switches from electron to hole, consistent with the ambipolar electric field effect observed in conductivity and Hall effect measurements. Near charge neutrality point and at low temperatures, the gate dependent thermoelectric power follows the semiclassical Mott relation using the expected surface state density of states, but is larger than expected at high electron doping, possibly reflecting a large density of states in the bulk gap. The thermoelectric power factor shows significant enhancement near the electron-hole puddle carrier density ~ 0.5 x 10 12 cm -2 per surface at all temperatures. Together with the 2 expected reduction of lattice thermal conductivity in low dimensional structures, the results demonstrate that nanostructuring and Fermi level tuning of three dimensional topological insulators can be promising routes to realize efficient thermoelectric devices.KEYWORDS Topological Insulators, Thermoelectric Power, Ambipolar Electric Field Effect, Bismuth Selenide, Charge Transfer Doping.The efficiency of thermoelectric devices is determined by the thermoelectric figure of merit ZT = σS 2 T/κ, where S is thermoelectric power (Seebeck coefficient) and σ and κ are electrical and thermal conductivity respectively. For a given thermal conductivity (typically dominated by phonons) and temperature, ZT is determined by the electronic structure of a material through the power factor σS 2 . Nanostructuring has long been seen as a promising route to increase ZT both through decreasing κ via phonon boundary scattering, and increasing the power factor through confinement-induced band structure effects 1 . The discovery that important thermoelectric materials Bi 1-x Sb x and Bi 2 (Se,Te) 3 [2][3][4] are in fact 3D topological insulators (TI) has triggered new directions to improve ZT via nanostructuring. The 3D TIs have an insulating bulk but metallic surface states with spin-momentum helicity which cannot be localized by nonmagnetic disorder 4,5 . Recent theoretical calculations 6,7 show that significant enhancement of ZT is expected in 3D TIs particularly in thin film geometry where top and bottom surfaces can hybridize and form a surface gap 8 .Thermoelectric power is also of great interest in understanding the electronic transport properties of Dirac electronic systems 9 , thus measurement of the thermoelectric properties of TI surface states can elucidate details of the electronic structure of the ambipolar nature of 3 topological metallic surface states that cannot be probed by conductance measurements alone 10 .Although there have been theoretical investigations of thermal and thermoelectric properties of Dirac materials including graphene and TIs 6,7,[11][12][13][14][15] and thermoelectric transport in carbon nanotubes 16 and graphene 9,17-19 have been studied expe...

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p-type doping of graphene with F4-TCNQ

Cited by 125 publications

References 17 publications

Structural and Electronic Properties of Graphene upon Molecular Adsorption: DFT Comparative Analysis

Structural and Electronic Properties of Graphene upon Molecular Adsorption: DFT Comparative Analysis

Charge neutrality and band-gap tuning of epitaxial graphene on SiC by molecular doping

Ambipolar Surface State Thermoelectric Power of Topological Insulator Bi₂Se₃

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p-type doping of graphene with F4-TCNQ

Cited by 125 publications

References 17 publications

Structural and Electronic Properties of Graphene upon Molecular Adsorption: DFT Comparative Analysis

Structural and Electronic Properties of Graphene upon Molecular Adsorption: DFT Comparative Analysis

Charge neutrality and band-gap tuning of epitaxial graphene on SiC by molecular doping

Ambipolar Surface State Thermoelectric Power of Topological Insulator Bi2Se3

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Product

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Ambipolar Surface State Thermoelectric Power of Topological Insulator Bi₂Se₃