Structural and magnetic studies of Cu-doped ZnO films synthesized via a hydrothermal route

Highly-textured n-type ZnO:Cu films with room-temperature ferromagnetism have been hydrothermally grown in aqueous solution at 90 °C using PLD-derived ZnO seed layers on different substrates (quartz, silicon, glass and sapphire). The crystallinity of the ZnO seed layers on different substrates plays an important role in the microstructure of the subsequently grown ZnO:Cu films. Better crystallinity and texture of the seed layers is favourable to the growth of continuous films. Thick Zn0.98Cu0.02O films (ca. 1.2 μm) exhibit high value of magnetic moment (0.40 μB per Cu), comparable to the previously reported value of thin films, indicating that thick ZnO:Cu films with high magnetization can be synthesized via this hydrothermal route. The incorporation of hydrogen into the ZnO lattice plays a dominant role in ferromagnetism in this ZnO:Cu system.