Photochemical Solution Deposition of Lead-Based Ferroelectric Films: Avoiding the PbO-Excess Addition at Last

Photoactivation of Sol–Gel Precursors for the Low‐Temperature Preparation of PbTiO3 Ferroelectric Thin Films

“…The value of remnant polarization (P r B11.9 mC/cm 2 ) is obviously lower than those obtained for PbTiO 3 -based thin films prepared at higher temperatures. 14,19,20,45 However, no ferroelectric hysteresis loops have been reported for ferroelectric thin films prepared at such a low temperature of 4001C, and the values of P r obtained in PT-based films prepared at 4501C (the lowest temperature reported until now where ferroelectric hysteresis loops have been obtained) are similar to that measured here. 19,20 In addition, this P r value ofB11.9 mC/cm 2 is in the limit of the switching charge density required for NVFeRAMs into the CMOS technology.…”

“…The best results appear to be obtained when a β‐diketonate complex is used (e.g., ACAC), because these complexes have characteristic absorption bands in the ultraviolet (UV) region 18 . Therefore, photochemical solution deposition (PCSD) has been recently proved as a deposition technique that combines CSD and UV‐irradiation, and that makes possible the preparation of oxide‐based films at relatively low temperatures 9,14,19,20 …”

“…18 Therefore, photochemical solution deposition (PCSD) has been recently proved as a deposition technique that combines CSD and UV-irradiation, and that makes possible the preparation of oxide-based films at relatively low temperatures. 9,14,19,20 It seems not to be a thermal effect of UV light that enhances crystallization, but an electronic excitation induced by UV photons through a charge transfer from O 2À to M n1 . 21,22 When certain molecules are irradiated with UV light of appropriate wavelength, they can absorb the photons and transit to an excited state in which they are unstable and thus very reactive.…”

“…[23][24][25] Particularly, CSD films with ferroelectric response are prepared at relatively low temperatures, between 4501 and 5501C. 14,19,20,26,27 However, many of these methods have problems for a real integration of the ferroelectric active layer with the microelectronic device, such as the cross-contamination due to the volatilization of PbO excess, or a low uniformity and poor stoichiometry of the layer. This strongly affects the functionality of the film.…”

Lead‐Free Ferroelectric (Na1/2Bi1/2)TiO3–BaTiO3 Thin Films in the Morphotropic Phase Boundary Composition: Solution Processing and Properties

“…adjustment of the physico‐chemical properties of the precursor (molecular level homogeneity, enhanced reactivity, photo‐activity, etc. ), development of new compositions in thin film form, or control of the microstruture, heterostructure, and physical properties of the crystalline film 20–23 …”