Bottom electrode dependence of electrical and optical properties in Bi0.96Sm0.04Fe0.98Mn0.02O3 films

Abstract

Bi0.96Sm0.04Fe0.98Mn0.02O3 (BSFM) films with ITO/glass (ITO), FTO/glass (FTO), Pt/Ti/SiO2/Si (Pt) as the bottom electrode and Au as the top electrode were prepared using the sol-gel method. The crystal structure, phase composition, oxygen vacancy content, dielectric property, ferroelectric and leakage characteristics, optical absorption and aging property of BSFM films with different bottom electrodes were studied. XRD results show that BSFM films with different bottom electrodes have different crystallinities, and that no heterophase is formed in all films and contains R3c and Pnma phases. SEM and TEM analysis shows that the BSFM film deposited onto ITO exhibits good grain growth and a dense surface structure, and the cross-section shows that the thickness of the prepared film is approximately 445 nm. XPS analysis shows that the film with the ITO bottom electrode has the smallest oxygen vacancy content. Concurrently, ferroelectric and leakage tests show that the film deposited onto ITO has the largest remnant polarization strength (2Pr = 92.35 μC/cm2) and the smallest leakage current density. Under a 200 kV/cm electric field, the leakage current density is 7.47 × 10−5 A/cm2, which is approximately 2 orders of magnitude lower than that with the Pt bottom electrode (1.16 × 10−3 A/cm2). Concurrently, the band gap (2.60 eV) of BSFM films can be narrowed using ITO as the bottom electrode. In addition, the BSFM films deposited onto ITO exhibit excellent ferroelectric and dielectric stability.