Repeatability of structural and ferroelectric properties of PLZT thin films prepared using three distinct sol–gel based solution routes
摘要
Sol–gel, a chemical solution deposition method, is widely used for preparing advanced materials due to its low fabrication cost, stoichiometric control, and compatibility with large-area thin film fabrication without the need for high vacuum environment. One such material is lead lanthanum zirconate titanate (PLZT) which is ferroelectric in nature, but its film properties are highly sensitive to the preparation method of the precursor solution (Sol). Achieving consistent and repeatable film properties remains a significant challenge for device applications. In this study, three distinct sol–gel based solution routes were employed to prepare PLZT “Sols”: (i) open beaker method (Sol1), (ii) reflux method (Sol2), and (iii) reflux with distillation method (Sol3). From each “Sol,” a set of three films were prepared under identical conditions (nine films total) and evaluated for structural and ferroelectric properties to assess the impact of “Sol” preparation method and the repeatability within each set. One representative sample from each set was further selected for detailed analysis of surface morphology and elemental composition. The results demonstrate that “Sol” chemistry has a pronounced impact on film quality and repeatability. “Sol3,” prepared using the reflux with distillation method provided a more controlled chemical environment, yielding a uniform and stable solution thereby resulting in films with improved crystallinity, uniform surface morphology, and stoichiometry closest to the target composition. Moreover, Sol3 films exhibited enhanced ferroelectric behavior, including the highest saturation (~ 50 µC/cm2) and remnant (~ 15 µC/cm2) polarizations, along with a low leakage current density ~ 10−9 A/cm2. “Sol3” proved to be a more reliable route for achieving better properties and repeatable results compared to “Sol1” and “Sol2.”