Spin-coated BiFeO3 films on Si wafers: Low processing temperature but prominent piezoelectricity

The direct integration of crystalline oxide layers with industrial Si substrate, specifically compatible with CMOS technology, requires the development of relatively simple, low-temperature processing routes below 450 °C. Here, a novel nonstoichiometric approach is proposed to achieve fabrication of BiFeO₃ films at 450 °C. Of particular importance is that, a saturation and remnant polarization of ∼80 μC/cm² and ∼60 μC/cm² and a strain as large as 1% are obtained. This strain stands as one of the most impressive values reported for thin films, comparable to the most superior strain obtained in ferroelectric films fabricated at temperatures exceeding 700 °C. The current work provides a new paradigm with significant simplicity and novel efficacy in reducing processing temperatures, as well offers a promising material for memory and piezo-driven actuating applications, especially meeting the increasing demand for precision position control systems at the nanometer scale.