Current–voltage characteristics of manganite based p–n interfaces: Role of swift heavy ion irradiation and defect annihilation

Abstract

We report current–voltage (I–V) device characteristics of pulsed laser deposition (PLD) grown La0.5Gd0.2Ca0.3MnO3 (LGCMO) manganite thin films on single crystalline (100) Nb:SrTiO3 (SNTO) substrates. LGCMO films were irradiated using 100 MeV O+9 swift heavy ions (SHI). The θ–2θ X–ray diffraction (XRD) and atomic force microscopy (AFM) measurement were performed at room temperature, respectively, for understanding the structural and microstructural behaviors of the films. The current–voltage (I–V) data were taken under the bias voltage applied across LGCMO/SNTO p–n interfaces at room temperature. Observed I–V behaviors for all interfaces have been discussed in the context of lattice strain, grain size and grain boundary density. To study the effect of annihilation on the irradiated LGCMO films, 50 nm thick ZnO layer was grown on the surface of LGCMO/SNTO films using chemical solution deposition (CSD) method under oxygen environment with a controlled flow. XRD, AFM and I–V measurements were performed again for annealed ZnO/LGCMO interfaces. Observed I–V characteristics across ZnO/LGCMO interface have been discussed in details in the context of annihilation induced modifications in the interface, structural strain and surface morphology.