Ferroelectric (Bi,Dy)4Ti3O12 thin films deposited on Pt(111)/Ti/SiO2/Si and p-type Si(100) substrates

Bi3.4Dy0.6Ti3O12 (BDT) thin films have been successfully deposited on Pt(111)/Ti/SiO2/Si and p-type Si(100) substrates by a sol–gel spin coating process. The remanent polarization (2Pr) and coercive field (2Ec) values of the BDT thin film on Pt(111)/Ti/SiO2/Si substrate annealed at 700°C were 39μC/cm2 and 367kV/cm at an electric field of 400kV/cm, respectively. This 2Pr value is larger than that of lanthanum-substituted Bi4Ti3O12 thin film and comparable with those of the samarium or neodymium-substituted Bi4Ti3O12 thin films. Moreover, the BDT thin film capacitors did not show a significant fatigue up to 1.45×1010 switching cycles at a frequency of 1MHz. The BDT thin films on p-type Si(100) substrates exhibit good capacitance–voltage (C–V) characteristics and a memory window of approximately 1.2V with sweep voltage of ±10V. The humps and valleys observed in C–V curves were interpreted by introducing charge injection from semiconductor to ferroelectrics. Furthermore, the frequency and the temperature dependency of C–V characteristics for the metal-ferroelectrics-semiconductor structured BDT thin films were measured. From these results, we suggest that the BDT thin film is one of the suitable dielectric materials for ferroelectric random access memory applications.