Highly conductive epitaxial ZnO layers deposited by atomic layer deposition

•High-quality epitaxial ZnO layers were deposited with ALD on GaN above 270 °C.•In the Al-doped layers, domains with different orientations also appear.•Lower-temperature epitaxy is possible with an epitaxial seed layer.•The conductivity of the epitaxial layers is between 0.6 and 2 * 10− 4 Ω cm.•The high carrier concentration is resulted by the Ga and Al doping

The possibility of depositing conductive epitaxial layers with atomic layer deposition has been examined. Epitaxial ZnO layers were grown on GaN and doped with Al. The resistivity of the epitaxial layers is between 0.6 and 2 * 10 −4 Ω cm with both the mobilities and the carrier concentrations being very high. The source of the high carrier concentration was found to be a combination of Al and Ga doping, the latter resulted by Ga atoms diffusing into the ZnO from the GaN substrate.