Structural investigation of thin SrTiO3 films grown on MgO and LaAlO3 substrates

Structural investigations of SrTiO3 thin films deposited by pulsed laser ablation onto MgO and LaAlO3 substrates are presented. The residual strain along the c -axis (the growth direction) was evaluated with conventional X-ray diffraction. Evaluation of the in-plane strain was accomplished with grazing-incidence X-ray diffraction. The unit cell of the STO film on LAO substrate had an orthorhombic structure with a coexistence of compressive strain along a -axis and tensile strain along b -axis. The film on an MgO substrate was tetragonal, stretched along the c -axis and compressed in-plane . The elemental composition of the samples was investigated using an INCA system for X-ray elemental analysis attached to a Hitachi S-4300 SEM. A comparison of the residual strain and stoichiometric ratio between as-deposited films and films annealed for four hours at 1100degreesC in flowing oxygen is presented.