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

Highlights: • PLD grown LGCMO manganite films on Nb:SrTiO3 substrates. • 100 MeV O⁺⁷ ions irradiation performed with different fluences i.e. 5 × 10¹¹ to 5 × 10¹³ ions/cm². • Current – Voltage Characteristics across LGCMO–SNTO p–n interface has been studied at room temperature. • Defects induced modification of structural and microstructural properties were investigated. • Effect of annihilation in current–voltage characteristics were discussed in details. We report current–voltage (I–V) device characteristics of pulsed laser deposition (PLD) grown La_0.5Gd_0.2Ca_0.3MnO₃ (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.