Film Thickness Dependence of Rectifying Properties of La1.85Sr0.15CuO4/Nb-SrTiO3 Junctions

In this work, p-n junctions are made from directly depositing optimal doped La1.85Sr0.15CuO4 (LSCO) films on n-type Nb-doped SrTiO3 substrates. Film thickness controlled rectifying behaviors are strikingly displayed. The starting points of the diffusion voltage reduction Vd-on change clearly with varying film thickness. Vd-on and TC coincide with each other when the film thickness is larger than 300 nm, indicating a close relation between the two parameters. However, when the film is very thin (<350 nm) a departure between the two parameters was also observed. A possible reason for this is discussed within the framework of an inhomogeneous Schottky contact. Enhanced interface inhomogeneity due to the tensile strain appears to be the origin.