Deposition of Al doped ZnO layers with various electrical types by atomic layer deposition

AlZnO thin films with various Al/Zn composition ratios were deposited by atomic layer deposition (ALD) at 200 °C. The effect of the composition of the AlZnO films on their electrical and optical characteristics was investigated. The AlZnO films with an Al content of up to 10 at.% showed high conductivity, while further increasing in the Al content resulted in the abrupt formation of an insulating oxide film. The lowest electrical resistivity of the ALD-deposited AlZnO film was 6.5 × 10− 4 [Ω cm] at 5 at.% Al. The AlZnO films with up to 5 at.% Al exhibited crystalline phases and a near-band-edge emission. With increasing Al content, the optical band edge showed a blue shift, and a sudden shift associated with an insulating bandgap was observed in the AlZnO films containing 20 at.% Al.