Epitaxial copper oxide thin films deposited on cubic oxide substrates

We study the growth conditions of Cu2O thin films deposited on MgO (001) and SrTiO3 (001) substrates by pulsed laser ablation, in order to explore the compatibility between semiconducting p-type Cu2O and other perovskite oxides in view of the fabrication of oxide electronics heterostructures. We find that in both cases perfect epitaxy, high crystalline quality and good out-of-plane orientation are achieved. In this context, epitaxy plays a major role in driving the phase formation. On the other hand, in films deposited at temperatures higher than 700 degrees C transport is inhibited by poor grain connectivity, which is an inevitable consequence of the necessity for the crystal to release the lattice strain. Instead, better connectivity and bulk-like values of resistivity, as well as good crystallinity and orientation, are obtained for films deposited at 650 degrees C. This should be kept in mind for the fabrication of stacked layer oxide heterostructures, where deep grooves between adjacent grains would be a serious drawback both for vertical and planar transport.