Nanocomposites and nanomaterials

Effect of electron irradiation on the electrical сonductivity of chemically reduced graphene oxide

O.O. Voitsihovska 1, R.M. Rudenko1, V.Yu. Povarchuk1, 
A.A. Abakumov2, I.B. Bychko2, M.O. Stetsenko3, M.P. Rudenko4

1 Institute of Physics, National Academy of Sciences of Ukraine, 46 avenu Nauky, Kyiv, 03680, Ukraine, e-mail: voleyna@ukr.net
2L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 avenu Nauky, Kyiv, 03028, Ukraine
3 V.E. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 41 avenu Nauky, Kyiv, 03028, Ukraine
4 Mykola Gogol State University of Nizhyn, 2 Grafska Str., Nizhyn, 16600, Ukraine

This paper presents the results of experimental studies of the effect of electron irradiation on the electrical conductivity of films of reduced graphene oxide (rGO).  The rGO film was formed from the reduced graphene oxide which was obtained by a modified Hammers method, the reduction was carried out with hydrazine hydrate. The film thickness was 10 μm. Measurement of the electrical resistivity was carried out by the van der Pauw method in the temperature range 5 – 300 K. Irradiation of the samples was carried out at room temperature by 1 MeV electrons in the dose range 1×1015 – 1.6×1017 cm-2.
It was shown that the temperature dependence of the resistivity of the rGO film over a wide temperature range is described by the expression of variable range hopping conductivity ρ=ρ0exp(T0/T)1/2 [1]. At low temperatures and sufficiently large electric fields (more than 104 V/m), we observed the dependence of the resistivity of the sample on the magnitude of the applied electric field. This indicates that the Efros-Shklovskii variable range hopping conductivity mechanism is realized in the studied samples. The value of the characteristic temperature T0 for the non-irradiated sample was 1950 K, and after 1.6×1017 cm-2 electron irradiation dose it was T0=1180 K. The decrease of the value of the characteristic temperature may indicate an increase in the localization length of the charge carriers. Analysis of the ρ (T) dependences shows that the electron irradiation in the dose range 1×1015–1.6×1017 cm-2 does not change the film conductivity mechanism.
The effect of electron irradiation on the rGO resistivity is non-monotonic in nature. Resistivity decreases with increasing irradiation dose from 1×1015 to1×1016 cm-2, then increases from 1×1016 cm-2 and finally decreases again when the irradiation dose is above 2×1016 cm-2. This behavior of the resistivity is similar for all temperatures, which may indicate changes in possible paths of current flow in disordered films [2]. 
1. D. Joung, S. I. Khondaker. Phys. Rev. B 86, 235423, (2012).
2. E. Jin, J. He, K. Sheng et al. Acta Materialia 61, 6466, (2013).