Effect of Sr doping on LaTiO3 thin films

We report on the electric properties of La1 xSrxTiO3 (0 x 0.5) thin films fabricated by pulsed laser deposition method. Crystallographic measurement of the thin films showed the epitaxial c-axis perovskite structure. The electric property of LaTiO3 thin film, which is a typical Mott insulative material in bulk, showed insulative behaviour, while the Sr-doped films showed metallic conduction suffering electron–electron scattering. Below x = 0.1, the major carrier type was identified to be hole, and switched to electron with further increasing Sr-doping above x = 0.15. In fact, the switching from p-type to n-type for La1 xSrxTiO3 thin films is first demonstrated in this study. The transition suggests that effective Coulomb gap vanishes due to over-additional Sr doping.