Undoped and Al-doped ZnO films with tuned properties grown by pulsed laser deposition

Thin films of ZnO:Al (AZO) and pure ZnO have been grown by pulsed laser deposition (PLD) at a wide temperature range (200–500 °C) and at different partial oxygen pressures (5 × 10− 5–5 × 10− 2 mbar). The films have been characterized structurally, optically and electrically. It is observed that the presence of aluminum in the ZnO films results in an enlargement of the optical band gap (~ 3.8 eV) while the transmittance is increased in comparison to pure ZnO films, to approximately 85%. Furthermore, in the AZO films occurs a lowering of the resistivity to the order of magnitude of 10− 4 Ωcm. Finally, a sharp emission excitonic peak centered at 353.5 nm was observed for the highly conductive (3.3 × 10− 4 Ωcm) ZnO:Al films.