Film structure and ferroelectric properties of vanadium-doped Sr _0.8Bi _2.3Ta ₂O ₉ thin films

Vanadium-doped strontium bismuth tantalate Sr _0.8Bi _2.3(Ta _2-xV _x)O ₉ (SBTV) (x=0-0.8) have been prepared on Pt/Ti/SiO ₂/Si substrates using a metalorganic decomposition method. Well-crystallized and dense SBTV films can be obtained at an annealing temperature as lower as 650-700°C that can be attributed to the enhanced densification due to the addition of vanadium. With partial substitution of tantalum by vanadium up to x=0.15, a larger remanent polarization (2P _r) of 30.5 μC/cm ² can be obtained for the Sr _0.8Bi _2.3Ta _1.85V _0.15O ₉ film at 800°C that is attributed to the larger grain size and increased "rattling space." Furthermore, the vanadium substitution for tantalum ion can effectively reduce the leakage current density as lower as 5×10 ^-8A/cm ² at an applied electric field of 100 kV/cm because of the reduced mobility of charge carriers. However, the incorporation of vanadium does not cause appreciable negative effect on the fatigue endurance of Sr-deficient Sr _0.8Bi _2.3Ta ₂O ₉ films until more than 20 mol% (x=0.2) vanadium was added.