Pulsed-Laser Deposited 35 Bi(Mg_1/2Ti_1/2)O₃-65 PbTiO₃ Thin Films - Part II: Influence of A-Site Deficiency and Thickness Scaling on Electric Properties

35 Bi(Mg_1/2Ti_1/2)O₃-65 PbTiO₃ (35 BiMT-65 PT) thin films with varying levels of A-site deficiency were investigated as a potential candidate for high-temperature nonvolatile ferroelectric memories. PbTiO₃ seed layers utilized to nucleate the perovskite phase in A-site deficient films induced a thickness dependence to the ferroelectric hysteresis and dielectric permittivity. Adjusting for this, the dielectric response of the 35 BiMT-65 PT films is ≈ 960. The maximum dielectric permittivity was 430 °C at 1 MHz for A-site deficient films. The transition temperature is independent of film thickness to 85 nm. Tan(δ) remains less than 15% at 1 MHz regardless of film thickness and temperature up to 585 °C. High-temperature polarization-electric field hysteresis measurements show charge injection with increasing temperature, while positive-up-negative-down measurements show little temperature dependence of P-r up to temperatures of 200 °C. Poole-Frenkel emission dominated the high field leakage behavior. The refractive index measured by ellipsometry is 2.58 at 633 nm. All samples show significant retention loss. As the stoichiometry improves, retention improves such that >40% of the initial Δ P is retained over ≈ 280 min.