Substrate effect on structural and humidity sensing of sol-gel derived Er-BaTiO3 thin films

Abstract

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.