Role of Surface Modification and Defect Formation on the Resistive Switching Behavior of BiFeO 3 -Based Heterostructures by Dense Electronic Excitation

In the past few decades, electronic excitation-induced changes in BiFeO3 (BFO)-type systems have attracted a lot of attention due to their potential for modifying existing material properties and exploring applications. Dense electronic excitation led by Swift Heavy Ion (SHI) irradiation can modify the structural, optical, electrical, and magnetic properties of materials. In the present study, electronic excitation-induced modifications in the structural, microstructural, and resistive switching properties of Pulsed Laser Deposition (PLD)-grown 20% Ca-doped BFO-based heterostructures using a LaNiO3 (LNO) conducting buffer layer on LaAlO3 (LAO) (100) substrates have been studied by varying the ion fluences of 5 × 1010, 5 × 1011, 1 × 1012, and 5 × 1012 ions/cm2 of 150 MeV Ag11+ ions. X-ray diffraction confirms the single-phase nature of the heterostructure along with the modulation of the structural strain with ion fluences. Atomic force microscopy (AFM) measurements show changes in grain morphologies, including the formation of hillock-like and track-like defects after ion irradiation. Cross-sectional Scanning Electron Microscopy (SEM) and Rutherford Backscattering spectroscopy (RBS) measurements confirm the interface modifications due to ion irradiation, which play an important role in charge conduction. Interface modification, formation of oxygen vacancies, and structural defects due to SHI irradiation affect the resistive switching and charge conduction in the proposed system, which is also validated by theoretical fittings of the space charge-limited conduction mechanism. In addition, the impact of ion irradiation on the optical band gap has been understood using UV–visible spectroscopy and correlated with other results.