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Perovskite erbium doped barium titanate (Ba1-xErxTiO3) thin films, at different x values, have been fabricated on SiO2/Si substrate and characterized using X-ray diffraction (XRD) in the range of 20° to 60° to study the phase structure and geometric parameters for the films. XRD patterns show a broadening and shifting for the perovksite peaks toward higher angle due to Er 3+ doping. The effect of Er 3+ substitution into BaTiO3 lattice has been deeply investigated using X-ray line profine analysis through Scherrer equation, Williamson-Hall and size-strain plot (SSP) approaches. For all approaches used, it has been found that the crystallite size for the films decreases as the value of x increases, which is attributed to the relatively small Er 3+ ionic size compared to Ba 2+ . In Williamson-Hall and SSP analysis, it is found that the microstrain created due to Er 3+ doping causes distortion for the lattice and broadening for perovskite peaks as a result. Among all approaches used in this work, SSP shows to be the most suitable for this type of materials by giving the best fitted plots and goodness of fit R 2 close to 1.

Abstract. Sol-gel erbium doped barium titanate (Er-BaTiO 3 ) thin films have been coated on SiO 2 /Si, fused silica, and Pt/Ti/SiO 2 /Si substrates. The crystallinity and phase of the thin films have been identified using X-ray diffractometer (XRD). The effect of substrate type on the surface morphologies of the films has been investigated using atomic force microscope (AFM). The influence of humidity on the electrical properties of Er-BaTiO 3 films has been carried out using semiconductor parameter analyzer (SPA). XRD patterns show that the films are crystallized with perovskite structure. AFM microimages show well-distributed grains, dense and crack-free surface for the films. The film fabricated on fused silica substrate gives the smoothest surface with smallest grain size, whereas the film coated on Pt/Ti/SiO 2 /Si gives a relatively rough surface with the largest grain size among the other substrates. The resistance values of the Er-BaTiO 3 films at different humidity percentages show that a decrement trend with the humidity percentage and the coated film on SiO 2 /Si substrate has the lowest resistance values compared with the films on other substrates, indicating that SiO 2 /Si substrate gives the best conduction and it could be a good candidate for humidity sensor for such type of material.

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