Crystallinity and electrical properties of neodymium-substituted bismuth titanate thin films

We report on the properties of Nd-substituted bismuth titanate Bi4 − xNdxTi3O12 (BNdT) thin films for ferroelectric non-volatile memory applications. The Nd-substituted bismuth titanate thin films fabricated by modified chemical solution deposition technique showed much improved properties compared to pure bismuth titanate. A pyrochlore free crystalline phase was obtained at a low annealing temperature of 640 °C and grain size was found to be considerably increased as the annealing temperature increased. The film properties were found to be strongly dependent on the Nd content and annealing temperatures. The measured dielectric constant of BNdT thin films was in the range 172–130 for Bi4 − xNdxTi3O12 with x = 0.0–0.75. Ferroelectric properties of Nd-substituted bismuth titanate thin films were significantly improved compared to pure bismuth titanate. For example, the observed 2Pr and Ec for Bi3.25Nd0.75Ti3O12, annealed at 680 °C, were 38 μC/cm2 and 98 kV/cm, respectively. The improved microstructural and ferroelectric properties of BNdT thin films suggest their suitability for high density ferroelectric random access memory applications.