Growth of ferroelectric Ba0.8Sr0.2TiO3 epitaxial films by ultraviolet pulsed laser irradiation of chemical solution derived precursor layers

Abstract

Highly crystalline epitaxial Ba0.8Sr0.2TiO3 (BST) thin-films are grown on (001)-oriented LaNiO3-buffered LaAlO3 substrates by pulsed laser irradiation of solution derived barium-zirconium-titanium precursor layers using a UV Nd:YAG laser source at atmospheric conditions. The structural analyses of the obtained films, studied by X-ray diffractometry and transmission electron microscopy, demonstrate that laser processing allows the growth of tens of nm-thick BST epitaxial films with crystalline structure similar to that of films obtained through conventional thermal annealing methods. However, the fast pulsed nature of the laser employed leads to crystallization kinetic evolution orders of magnitude faster than in thermal treatments. The combination of specific photothermal and photochemical mechanisms is the main responsible for the ultrafast epitaxial laser-induced crystallization. Piezoresponse microscopy measurements demonstrate equivalent ferroelectric behavior in laser and thermally annealed films, being the piezoelectric constant ∼25 pm V−1.

Laser Irradiation of Metal Oxide Films and Nanostructures: Applications and Advances

“…In this context, laser irradiation appears as a potential alternative because laser irradiation exhibits a significantly fast and localized thermal effect without any interference with the underlying substrates or surrounding circuitry. Many studies have been conducted on the laser irradiation of dielectric, ferroelectric, and piezoelectric ceramic films for different purposes . Representative findings of some of these studies on laser irradiated electroceramic films are discussed below.…”

“…Laser systems operating in continuous‐wave (CW) or pulsed modes at wavelengths in the ultraviolet (UV), visible (vis), and infrared (IR) ranges have been employed to tailor the properties/functionality of metal oxides. Laser irradiation of a wide variety of MO films and nanostructures has been conducted for their applications in dielectric, ferroelectric, piezoelectric, and multiferroic magnetoelectric devices, photocatalysis, gas sensors, transparent conductors, field‐effect transistors, solar cells, and thermistors ( Figure ). Besides the overarching goal of tailoring of the physical and chemical properties, several interesting phenomena induced by laser irradiation have been reported, e.g., structural distortion and transformation, diamagnetic to ferromagnetic switching, modification of exchange bias, wettability switching, p‐type to n‐type conductivity transformation, resistive switching, metal‐to‐insulator transition (MIT), and electrochromic switching …”

“…Prior studies have demonstrated the evolution of polycrystalline, textured, and epitaxial microstructures of diverse MO films (e.g., tin‐doped indium oxide (ITO), Ga 2 O 3 , ZnO, TiO 2 , VO 2 , WO 3 , BaSrTiO 3 (BST), Pb(Zr,Ti)O 3 (PZT), La 1− x Sr x MnO 3 (LSMO)) deposited by methods such as chemical solution deposition (CSD), pulsed‐laser deposition (PLD), and sputtering . The large temperature gradients and high diffusion rates during laser processing lead to epitaxial growth rates that are orders of magnitude larger and effective heating times much shorter than that for conventional thermal treatment . Furthermore, the laser irradiation technique has been utilized for processing of complex nanostructures, such as site‐specific growth of nanowires (NWs) (e.g., ZnO, TiO 2 ) and nanorods (NRs) (e.g., Fe 2 O 3 , Ag/ZnO), spatial patterning of nanocrystals (e.g., ZnO) and NWs (e.g., Al 2 O 3 ), fabrication of nanosheets (e.g., Fe 2 O 3 ) and clustered nanostructures (e.g., Ag–ZnS@ZnO, Ag/WO 3− x ), production of oxide nanoparticles (NPs) by laser ablation in liquid (e.g., CuO, MnO x , Y 3 Fe 5 O 12 , Ag/TiO 2 , Y 2 O 3 :Eu 3+ , Gd 2 O 3 :Eu 3+ , Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce), Fe@Fe 2 O 3 , or Fe 3 O 4 ), in situ formation of nanocomposites (e.g., Co 3 O 4 , MoO 2 , and Fe 3 O 4 particles embedded in graphene, ZnO particles embedded in poly(methyl methacrylate)), selective patterning of hybrid electrodes (e.g., Ni/NiO), direct scribing of fine structures (e.g., ITO), and direct writing of microdevices (e.g., TiO 2 , Cu/Cu 2 O).…”

Low Voltage and Ferroelectric 2D Electron Devices Using Lead‐Free BaxSr1‐xTiO3 and MoS2 Channel

“…Hence, utilizing non‐toxic earth‐abundant substances for high‐performance and low‐power electronics must be a genuine and desirable research path for the sustainable future. For instance, as a new ferro/piezo‐electric materials beyond PZT (Lead Zirconate Titanate), Ba x Sr 1‐x TiO 3 (BST: Barium Strontium Titanate), solid solution form of BaTiO 3 and SrTiO 3 , could be one of the Pb‐free earth‐abundant examples presenting good tune‐ability in composition, aiming at low dielectric loss, high‐dielectric constants, ferroelectric properties, and ecofriendly device fabrications …”

Влияние материала подложки на структуру и электрофизические свойства тонких пленок Ba-=SUB=-x-=/SUB=-Sr-=SUB=-1-x-=/SUB=-TiO-=SUB=-3-=/SUB=-

“…В на-стоящее время ведутся интенсивные исследования ге-тероструктур, где в качестве диэлектрика используется тонкая сегнетоэлектрическая пленка Ba x Sr 1−x TiO 3 [3][4][5].…”