Structural properties of the epitaxial CuCr0.95Mg0.05O2 thin films on c-plane sapphire substrates by pulsed laser deposition

We report an investigation of the structural properties of CuCr0.95Mg0.05O2 films on c-plane sapphire substrates using pulsed laser deposition. The thin films were grown at different temperatures of 500, 600, and 700 °C with an oxygen partial pressure of 10 mTorr. c-axis oriented epitaxial CuCr0.95Mg0.05O2 thin films on c-plane sapphire substrates with an in-plan 30° rotation were obtained. The sixfold rotational symmetry in the pole figures from the (0 1 2) plane indicates that there are two different types of crystal grains in which the a-axes rotate by 60° with respect to each other around the c-axis. The reason for the 30° rotation is assumed to be the presence of the ∼10% mismatch of oxygen distance between the c-plane sapphire substrate and the CuCr0.95Mg0.05O2 on the c-plane. The epitaxial crystallographic relationship between CuCr0.95Mg0.05O2 and Al2O3 was (0 0 0 6)CuCrO2//(0 0 0 3)Al2O3 and [1 0 −1 0]CuCrO2//[1 1 −2 0]Al2O3. The presence of twins in the films and the surface morphology were investigated using transmission electron microscopy and scanning electron microscopy, respectively.