Ta doping-induced enhancement of dielectric performance in sputtered BaTiO 3 thin films for MIM capacitors

Abstract Conventional dielectric materials, owing to their limited charge-storage capacities, are insufficient to satisfy the miniaturization demands of modern electronics. Consequently, the enhancement of dielectric permittivity has emerged as a primary research focus in recent years. In this study, the deposition of Ta-doped BaTiO 3 thin films by magnetron co-sputtering is reported for the first time. Ta-doped BaTiO 3 thin films were characterized in comparison with BaTiO 3 and Ta 2 O 5 , with emphasis on their suitability as dielectric layers in metal–insulator–metal (MIM) capacitors. To tailor the material properties, a constant RF power was applied to the BaTiO 3 target, while the DC power of the Ta target was varied. XRD analysis revealed that all the as-deposited films exhibit an amorphous structure. FESEM and AFM studies showed that pure BaTiO 3 and Ta 2 O 5 thin films possessed smooth and crack-free surfaces, whereas the incorporation of Ta into BaTiO 3 promoted the formation of fine grains. EDX analysis revealed that increasing the DC sputtering power (10 to 20 W) resulted in a rise in Ta atomic concentration from 0.85% to 1.32%. UV–Vis spectroscopy demonstrated that Ta doping led to an increase in the indirect bandgap (3.75 eV to 3.90 eV). Impedance spectroscopy of MIM capacitors showed that the substitution Ti 4+ with Ta 5+ led to a significant enhancement in dielectric constant, from 18.96 in BaTiO 3 to 38.33 in 1.32 at% Ta-doped BaTiO 3 . The dielectric loss displayed a frequency-dependent relaxation behavior. The concurrent doubling of the breakdown voltage and increase in capacitance significantly enhanced the overall charge-storage capacity, indicating that Ta doping represents a promising approach for optimizing BaTiO 3 thin films for high-performance energy storage applications.