DC and AC Hopping transport in metal/amorphous carbon nitride/metal devices

Hopping electrical transport has been investigated in amorphous carbon nitride in both DC and AC modes, as a function of temperature T, electric field F and frequency. The strong field enhancement of the current for F> 5 x 10 4 V cm -1 , causing a departure from the Mott law at low field, i.e. the linear dependence of ln(σ OHMIC ) vs (T 0 /T) 1/4 , is also observed in the AC conductance data. Both conductance and equivalent parallel capacitance are discussed in the framework of a universal model of AC transport with spatially randomly distributed energy barriers. The inverse characteristic time 1/τ, which also follows Mott's law, is compatible with the filling rate Γ F (E DL ) of empty states at the transport energy, which governs the DC conductivity.