Magnetoresistance and Charge Transport in Graphene Governed by Nitrogen Dopants

Abstract

We identify the influence of nitrogen-doping on charge- and magnetotransport of single layer graphene by comparing doped and undoped samples. Both sample types are grown by chemical vapor deposition (CVD) and transferred in an identical process onto Si/SiO2 wafers. We characterize the samples by Raman spectroscopy as well as by variable temperature magnetotransport measurements. Over the entire temperature range, the charge transport properties of all undoped samples are in line with literature values. The nitrogen doping instead leads to a 6-fold increase in the charge carrier concentration up to 4 × 10(13) cm(-2) at room temperature, indicating highly effective doping. Additionally it results in the opening of a charge transport gap as revealed by the temperature dependence of the resistance. The magnetotransport exhibits a conspicuous sign change from positive Lorentz magnetoresistance (MR) in undoped to large negative MR that we can attribute to the doping induced disorder. At low magnetic fields, we use quantum transport signals to quantify the transport properties. Analyses based on weak localization models allow us to determine an orders of magnitude decrease in the phase coherence and scattering times for doped samples, since the dopants act as effective scattering centers.

Electronic Transport Properties of 1D‐Defects in Graphene and Other 2D‐Systems

“…However, defects in graphene can lower its electron mobility significantly and degrade its electron transport properties. Lattice defects such as vacancies and dopant atoms have been shown to lead to additional scattering in graphene. Moreover, mechanical deformation, bending and strain can significantly change graphene's electronic transport properties .…”

Grain structures of nitrogen-doped graphene synthesized by solid source-based chemical vapor deposition

“…The doping with heteroatoms creates charged sites in the graphene lattice, as a result the spin and charge densities are redistributed bringing new functionalities [16]. In this prospect, nitrogen incorporation in graphene by substitution of carbon atoms has been explored significantly to achieve high electron density, n-type doping, increased capacity of battery, high supercapacitance and oxygen reduction activities [16][17][18][19][20][21][22]. Thus, various studies have revealed that nitrogen doping can be exciting platform to tune or introduce novel properties in graphene.…”

Doping of Graphene by Low-Energy Ion Beam Implantation: Structural, Electronic, and Transport Properties

“…For high fields, we observe a positive MR for undoped samples as seen by others 31,32 which here follows a B 2 -dependence. Thus, we interpret this as a classical Lorentz MR. 31 This behavior changes to negative MR for ion-implanted samples, which is for undoped samples only found for small fields. Consequently, the presence of atomic scale defects leads to this change to negative MR. Interestingly, in the case of nitrogen implantation the change is much less than for boron and carbon, which could be explained with either a different scattering potential or the absence of lattice defects.…”