Structural and electrical studies on rapid thermally processed ferroelectric Bi₄Ti₃O₁₂ thin films by metallo-organic solution deposition

Abstract

Thin films of Bi₄Ti₃O₁₂ that were pinhole free with uniform composition and thickness were prepared by the metallo-organic solution deposition technique on platinum coated silicon and bare silicon substrates. Crack free and crystalline films of 5000 Å thickness were fabricated by spinning and post deposition rapid thermal annealing treatment at 500° C. The films exhibited good structural, dielectric, and ferroelectric properties. The effects of annealing temperature and time on the structural and electrical properties of the films were evaluated. The measured small signal dielectric constant and dissipation factor at a frequency of 100 kHz were 184 and 0.039, respectively for a film rapid thermally annealed at 700° C for a time of 10 s. Room temperature resistivity of 108 Ωcm and leakage current density of less than 10^-7 A/cm² were obtained for a 0.5-µ m-thick film at an applied electric field of 100 kV/cm; establishing good insulating behavior. Ferroelectricity was confirmed by P-E hysteresis loops with remanent polarization and coercive field values of 4.4 µ C/cm² and 84 kV/cm, respectively. The high frequency C-V measurements on films in metal-ferroelectric-semiconductor configuration indicated good Si/Bi₄Ti₃O₁₂ interface characteristics. The films showed good switching endurance under bipolar stressing at least up to 10¹⁰ switching cycles.