Study on the Influence of Deposition Temperature on the Properties of Lanthanum Titanate Films

The work aims to study the effect of deposition temperature on optical properties and residual stresses in Lanthanum titanate (H4) films. The LaTiO3 films were deposited by electron-beam thermal evaporation technique. The residual stress of LaTiO3 films on fused silica was characterized macroscopically and microscopically, using laser interferometry and AFM. The residual stresses and surface profile shape change were simulated using finite element analysis methods. It was confirmed that the deposition temperature did not affect the optical properties of the films， but did for residual stresses. The residual stress of LaTiO3 films changes from decreasing tensile stress to compressive stress as the deposition temperature increases. The deposition temperature is used to modulate the magnitude and transition of the residual stress in the films. There is a strong dependence between the residual stresses and the densities of surface columnar structures in LaTiO3 films. The effect of density of surface columnar structures is found as follows: the film with the lower density of surface columnar structures generally shows a tensile and high density easily transform into compress stress. This conclusion is also verified by the increase of the corresponding refractive index. The simulated surface profiles are basically overlapping with the measured data. The proposed model is validated for the simulation of residual stresses in monolayers.