Electron–Hole Symmetry Breaking in Charge Transport in Nitrogen-Doped Graphene

Abstract

Graphitic nitrogen-doped graphene is an excellent platform to study scattering processes of massless Dirac fermions by charged impurities, in which high mobility can be preserved due to the absence of lattice defects through direct substitution of carbon atoms in the graphene lattice by nitrogen atoms. In this work, we report on 2 electrical and magnetotransport measurements of high-quality graphitic nitrogen-doped graphene. We show that the substitutional nitrogen dopants in graphene introduce atomically sharp scatters for electrons but long-range Coulomb scatters for holes and, thus, graphitic nitrogen-doped graphene exhibits clear electron-hole asymmetry in transport properties. Dominant scattering processes of charge carriers in graphitic nitrogen-doped graphene are analyzed. It is shown that the electron-hole asymmetry originates from a distinct difference in intervalley scattering of electrons and holes. We have also carried out the magnetotransport measurements of graphitic nitrogen-doped graphene at different temperatures and the temperature dependences of intervalley scattering, intravalley scattering and phase coherent scattering rates are extracted and discussed. Our results provide an evidence for the electron-hole asymmetry in the intervalley scattering induced by substitutional nitrogen dopants in graphene and shine a light on versatile and potential applications of graphitic nitrogen-doped graphene in electronic and valleytronic devices. KEYWORDS: graphene, charge transport, intervalley scattering, graphitic nitrogen doping, atomically sharp scattering center Graphene, a honeycomb lattice of single layer carbon atoms with a Dirac-like energy dispersion, has attracted extensive interests in recent years owing to its extraordinary charge transport properties and potential applications in electronic devices. [1][2][3][4][5] However, charge impurities universally exist in graphene and influence its electronic properties. [6][7][8][9][10] A particular case is when approaching the Dirac point at which, because of the vanishing density of states, the transport properties of graphene are expected to be highly sensitive to 3 scattering from charged impurities. [6][7][8][9][10] Previous studies of charge carrier scattering in graphene are mainly achieved with the scattering centers introduced by physical methods, such as ion irradiation, 7, 8 adsorption of adlayers, 9 low temperature deposition 10 and spin coating [11][12][13] of nanoparticles, and atomic hydrogen adsorption. 14 These methods could inevitably induce randomness and disorder in graphene and thereby largely degrade its transport properties. Compared with the physical methods, chemical doping has the advantage to achieve scattering centers in graphene with good replicability, lattice stability, and tunablity of doping concentration through the substitution of carbon atoms in the graphene lattice by dopant atoms. Among numerous dopants, nitrogen (N) atoms can be chemically incorporated into graphene forming covalent bonds with carbon (...

Electronic properties of chemically doped graphene

“…Electron-hole asymmetry was also found at high magnetic field, where it was seen that the quantum Hall states were more robustly defined on the hole side than on the electron side. All these observations were tentatively explained by the fact that the nitrogen dopant, after providing electron to the graphene lattice, acts as a positively-charged scattering center with different effects on electrons and on holes : positive holes would be scattered off the nitrogen with smaller scattering angle [126]. Note that indications of such an electron-hole asymmetry in electronic transport was reported in earlier work [115,118].…”

“…Perhaps the most comprehensive study on the electronic transport properties of N-doped graphene so far was by Li et al [126] (Fig. 22).…”

The Thermal, Electrical and Thermoelectric Properties of Graphene Nanomaterials

“…Therefore, physical and chemical doping of graphene can be used to improve its electrical properties. Among many dopants, both theories and experiments have shown that an n-doped graphene lattice can realize n-doping and the carrier can maintain high mobility [55].…”

“…( c ) Raman spectra of a graphitic N-doped (2% N atomic concentration) graphene film (The letters on each Raman peak in the figure indicate the vibrational symmetry of the Raman peak.). Transport properties (conductivity ( d ), carrier concentration ( e ) and mobility ( f )) of as-formed N-doped graphene films [55]. Copyright 2017, American Chemical Society.…”

Edge Effect on the Photodetection Ability of the Graphene Nanocrystallites Embedded Carbon Film Coated on p‐Silicon

“…Nitrogen‐doped graphene is also a quite interesting issue. Nitrogen can donate electrons to graphene and provide extra quantum states at the Fermi level . It can be expected that the N‐doping should enhance the performance of GNEC film.…”