Swift heavy ion induced modifications in structural and electrical properties of LSMO/ITO thin films

In the present work, La₀.₇Sr₀.₃MnO₃ (LSMO) thin films were successfully deposited on indium tin oxide (ITO) substrates using the chemical solution deposition (CSD) spin-coating technique. To investigate the effect of defect engineering on the electrical and transport properties, the films were subjected to swift heavy ion (SHI) irradiation using 120 MeV Ag⁹⁺ ions at fluences of 1 × 10 ¹ ¹ and 1 × 10 ¹ ² ions/cm². Structural analysis using X-ray diffraction (XRD) revealed the predominantly amorphous nature of the deposited films, while emission scanning electron microscopy (SEM) and cross-sectional SEM confirmed uniform surface morphology and continuous film formation over the ITO substrate. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) verified the elemental composition and chemical states of the constituent elements. Electrical characterization through AC conductivity, dielectric, impedance, and current–voltage (I–V) measurements demonstrated a systematic reduction in electrical conductivity and charge transport with increasing ion fluence, attributed to irradiation-induced defect states, enhanced carrier trapping, and increased structural disorder within the amorphous matrix. AC conductivity analysis confirmed a correlated barrier hopping (CBH) conduction mechanism, accompanied by an increase in hopping barrier height with irradiation. Dielectric studies revealed a decrease in dielectric constant and slower relaxation dynamics with increasing defect concentration, indicating enhanced non-Debye behavior. The observed tunability of electrical transport and dielectric response through controlled SHI irradiation highlights the potential of LSMO/ITO thin films for defect-engineered electronic, dielectric, and functional oxide device applications.