Varistor characteristics of a nano-device containing graphene and   oxidized graphene: Verification by DFT + NEGF
  Electron transport and quantum conductance through an armchair graphene and its oxidized graphene- containing form were investigated by the density functional theory (DFT) method and the implementation of the non-equilibrium Green function (NEGF) approach. The computed $I-V_b$(current as a function of bias voltage) characteristic of the studied systems showed the tunneling phenomenon in bias and gate voltages considered. Along with the transport properties, electronic properties including density of states (DOS) were calculated in the studied systems. A close examination of the results showed that the $I-V_b$ curve for graphene behaved $I\propto V_be^{\lambda V_b}$ like at some bias voltages, while for the oxidized graphene-containing form, its trend was the same as that of a Voltage Dependent Resistor (VDR-VARiable resISTOR), $I\propto V_b^\beta$, at the whole range of the applied bias. 
Badie Ghavami, Alireza Rastkar-Ebrahimzadeh
cond-mat.mes-hall