Hopping conduction in nitrogen doped ZnO in the temperature range 10–300 K

Electrical transport mechanism in as-prepared and nitrogen (N) doped zinc oxide (ZnO) thin films has been investigated in the temperature range 10–300 K. The samples were grown by pulsed laser deposition in oxygen (O) ambience. The doped films show p-type conductivity at room temperature. It is found that there exist three distinct temperature regimes of the conduction in both as-prepared and N-doped ZnO in the said temperature range, viz., in the temperature range 10–50 K, variable range hopping is the dominant conduction mechanism whereas in the regime 50–210 K, the conduction is dominated by thermally activated hopping, whereas above 230 K, the transport is governed by the thermally activated carriers. However, a stable phase with no change in conductivity is observed in temperature range 210–230 K for N-doped ZnO. N-induced defects in ZnO lattice behave as localized hopping center, which does not have enough activation energy for conduction in this temperature regime.