Transport behavior and negative magnetoresistance in chemically reduced graphene oxide nanofilms

Abstract

The electron transport behavior in chemically reduced graphene oxide (rGO) sheets with different thicknesses of 2, 3, and 5 nm was investigated. The four-probe method for the sheet resistance (R(S)) measurement on the intensively reduced graphene oxide samples indicates an Arrhenius characteristic of the electron transport at zero magnetic field B = 0, consistent with previous experimental results on well-reduced GO samples. The anticipated variable range hopping (VRH) transport of electrons in a two-dimensional electron system at low temperatures was not observed. The measured R(S) of the rGO samples are below 52 kΩ/square at room temperature. With the application of a magnetic field up to 4 T, negative magnetoresistance in the Mott VRH regime was observed. The magnetotransport features support a model based on the spin-coupling effect from the vacancy-induced midgap states that facilitate the Mott VRH conduction in the presence of an external magnetic field.

Hopping magnetoresistance in ion irradiated monolayer graphene

“…In this work, we report the results of magnetoresistance (MR) measurements in samples of monolayer graphene strongly disordered with ion irradiation. MR in the VRH regime of conductivity has been observed earlier in different graphene-based structures: fluorinated graphene [4], graphene exposed to ozone [5], graphene oxide [6]. In Ref.…”

“…Defects are very useful tool to modify and control the physical properties of true two-dimensional (2d) material -monolayer graphene, therefore, disordered graphene attracts a lot of attention [1,2,3,4,5,6,7]. The evolution of optical (Raman spectra) and electronic (conductivity) properties of graphene with increasing disorder has been investigated in many papers (see, for example, [8,9,10,11]).…”

The Kondo effect in reduced graphene oxide films

“…Although other studies have reported a variation from VRH to activated transport 12 or space charge limited conduction 13, these mechanisms are still dominated by the effects of disorder. A recent study has shown activated transport in RGO indicating band‐like transport 14.…”

Solution‐Processed Ultrathin Chemically Derived Graphene Films as Soft Top Contacts for Solid‐State Molecular Electronic Junctions

“…Plots of ln( I / V ) vs 1/ T is shown in Figure 4d, and the linear‐fitting yields an activation energy of 13 meV. The fit indicates that the vertical transport through the CDG layers is governed by thermally activated transport26 and that this temperature dependence (although the junctions are fairly stable at each temperature, see Figure 4c inset) of the CDG film has an influence on the absolute junction resistance. At room temperature the resistance is dominated by the transport through the molecules but as the temperature is lowered the resistance of the CDG increases and can be expected to dominate at low temperatures.…”