X-ray and transmission electron microscopy structural characterization of multifunctional Perovskite thin films

Different multifunctional (PbTiO3, Sm0.6Nd0.4NiO3, NdMnO3) thin films were grown by metalorganic chemical vapor deposition (MOCVD) technique on SrTiO3 and LaAlO3 substrates. Transmission electron microscopy (TEM) and X-ray diffraction measurements reveal that almost single crystalline thin films can be epitaxially grown on the top of substrates. The relationship between the crystallographic orientation of the films and those of the substrates were determined by reciprocal space mapping and TEM analyses. PbTi03 thin films appear to be under tensile or compressive strain according to the different mismatch of their cell parameter with those of the substrate. Relaxation mechanism as a function of the film thickness arises from coexistence of different type of domains and size and strain effect are analyzed. SmNiO3 thin films present diffuse scattering strikes and are less well organized when compared to PbTi03 thin films. Different domains are observed as well as an additional parasitic phase close to NiO. Its regular distribution can be associated to reduced transport properties. Preliminary observations on NdMnO3 thin films shows that an amorphous phase is obtained during MOCVD that can be transformed in a single crystalline film by annealing. The films are under tensile or compressive strain according to the different mismatch of their cell parameter with those of the substrate. Magnetic properties are investigated.