Abstract
Electrical transport properties of the nano-graphene oxide were investigated by measuring current-voltage characteristics in the wide temperature range of 15 K∼450 K. The n-GO is composed of nanometer-sized intact graphene-like sp2 domains embedded in the sp3 matrix which acts as a charge transport barrier between the highly conductive sp2 domains. The oxygen in the n-GO has the concentration of 4.43 at% in the form of oxygen functional groups. Below the conduction band, four discontinuous localized states with the activation energies of 1.92 meV, 3.27 meV, 5.54 meV, and 6.58 meV were observed. These activation energies decrease with decreasing oxygen concentration and increasing external electric field in the n-GO material. Moreover, we found that the direct tunneling of charge carrier through the sp3 barrier was a dominant transport mechanism for the n-GO material. Also, unlike the activation energy of charge carrier, the transport barrier was independent of both the concentration of the oxygen functional groups and external electric field. The transport barrier was mainly determined by insulation property of the sp3 structure.
Highlights
Graphene oxide (GO) is attracting attention because its energy band structure and electrical conductivity can be changed by controlling concentration of oxygen functional groups.1–4 its electrical transport properties can be tuned through controlling chemical or thermal post-reduction processes.5–7 Depending on the concentration of oxygen functional groups, the GO can be a semimetal, semiconductor, and insulator.8–10 Recently, a nanographene oxide (n-GO) has been studied because it can be made as a homogeneous and large area electronic material
The reduced n-GO is composed of nanometer-sized intact graphene-like sp2 domains embedded in a sp3 matrix which acts as a charge transport barrier between the highly conductive sp2 domains
The currents passing through the n-GO sample at various d. c. biases of 0.001V, 0.01 V and 0.1 V are shown in Fig. 1 as a function of temperature for heating up process
Summary
Graphene oxide (GO) is attracting attention because its energy band structure and electrical conductivity can be changed by controlling concentration of oxygen functional groups. its electrical transport properties can be tuned through controlling chemical or thermal post-reduction processes. Depending on the concentration of oxygen functional groups, the GO can be a semimetal, semiconductor, and insulator. Recently, a nanographene oxide (n-GO) has been studied because it can be made as a homogeneous and large area electronic material. Graphene oxide (GO) is attracting attention because its energy band structure and electrical conductivity can be changed by controlling concentration of oxygen functional groups.. The carrier transport in metal/GO/metal structure depends on two processes: the carrier injection from the metal/GO interface and the subsequent transport in the GO bulk. The injection barrier at the interface is determined by the energy band structures of both the metal and the GO material It may either be zero for the semimetal GO and closes to the value of the GO band gap for the semiconducting GO, depending on the concentration of oxygen functional groups. We found that the thermal activation energies of the carrier depend on both the concentration of oxygen functional groups and the external electric field. In order to observe the effect of concentration of the oxygen functional groups, the n-GO sample was annealed at 400 K, 420 K, 440 K, 460 K and 480 K, in the vacuum chamber for 30 min, respectively
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