The effect of La doping concentration on optical and electrical properties of LaxSr1-xTiO3 thin film fabricated by sol-gel process

Strontium titanate (SrTiO3), a typical wide-band-gap perovskite oxide, is a promising candidate for the application of thin film transistor (TFT). In this paper, the LaxSr1-xTiO3 thin films with different doping concentration are fabricated by sol-gel method. X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), UV-Vis-NIR transmission spectroscopy and four point probe instrument are employed to characterize the crystal structure, surface profile, transmittance and resistivity of LaxSr1-xTiO3 thin films. The results show that LaxSr1-xTiO3 (x = 0.5 at.%, 1 at.%, 1.5 at.%, 2 at.%, 4 at.%, 6 at.%, 8 at.%, 10 at.%) thin films are single SrTiO3 cubic phase after La doping. Additionally, the SEM and AFM observation reveal dense grains and smooth surface. LaxSr1-xTiO3 film possesses high transmittance in visible region. The conductivity of LaxSr1-xTiO3 thin films is improved tremendously after La doping. The resistivity of La0.04Sr0.96TiO3 is 11.7 × 10− 3 Ω·cm and its transmittance is 88.66%.