Growth, structural and electrical properties of polar ZnO thin films on MgO (100) substrates

ZnO films have been grown on (100) oriented MgO substrates by pulsed-electron beam deposition in the room temperature to 500 °C range. Highly (00•2) textured films are obtained for a growth temperature higher than 200 °C, and epitaxial films are formed at 500 °C with the following epitaxial relationships: (1-1•0)ZnO // (110)MgO and (11•0)ZnO // (110)MgO, despite the difference in symmetry between film and substrate. The low temperature resistivity curves evidenced a metal-semiconductor transition for the ZnO films grown in the 300 to 500 °C range which has been interpreted in the frame of the model of conductivity in disordered oxides.