Nanoscale Ferroelectric Switchable Polarization and Leakage Current Behavior in (Ba_0.50Sr_0.50)(Ti_0.80Sn_0.20)O₃ Thin Films Prepared Using Chemical Solution Deposition

Abstract

Nanoscale switchable ferroelectric (Ba0.50Sr0.50)(Ti0.80Sn0.20)O3-BSTS polycrystalline thin films with a perovskite structure were prepared on Pt/TiOx/SiO2/Si substrate by chemical solution deposition. X-ray diffraction (XRD) spectra indicate that a cubic perovskite crystalline structure and Raman spectra revealed that a tetragonal perovskite crystalline structure is present in the thin films. Sr2+and Sn4+cosubstituted film exhibited the lowest leakage current density. Piezoresponse Force Microscopy (PFM) technique has been employed to acquire out-of-plane (OPP) piezoresponse images and local piezoelectric hysteresis loop in polycrystalline BSTS films. PFM phase and amplitude images reveal nanoscale ferroelectric switching behavior at room temperature. Square patterns with dark and bright contrasts were written by local poling and reversible nature of the piezoresponse behavior was established. Local piezoelectric butterfly amplitude and phase hysteresis loops display ferroelectric nature at nanoscale level. The significance of this paper is to present ferroelectric/piezoelectric nature in present BSTS films at nanoscale level and corroborating ferroelectric behavior by utilizing Raman spectroscopy. Thus, further optimizing physical and electrical properties, BSTS films might be useful for practical applications which include nonvolatile ferroelectric memories, data-storage media, piezoelectric actuators, and electric energy storage capacitors.

Enhanced energy storage properties of epitaxial (Ba0.955Ca0.045)(Zr0.17Ti0.83)O3 ferroelectric thin films

“…Due to their unique combination of properties such as spontaneous and switchable polarization, piezoelectricity, and pyroelectricity, ferroelectricity, electrocaloric effect, photovoltaic effect and photocatalytic properties etc, perovskite‐based ferroelectric have been extensively studied for multifunctional applications including nonvolatile random access memories (NVRAMs), dynamic random access memories (DRAMs), high‐frequency (GHz) bypass capacitors, infrared detectors, as well as tunable devices in microwave electronics. In particular, ferroelectric materials are very much suitable for energy storage capacitors, multilayer ceramic capacitors (MLCCs), actuators, lead‐free piezoelectric transducers, and charge storage devices are particularly popular in power electronics, pulsed power applications, high‐power microwave systems etc 1‐5 …”

“…Suitable site engineering, that is doping or substitution either at or both A and B sites of ABO 3 ‐type perovskites, plays an important role in controlling both chemical and physical properties of the materials. Usually doping or substitution of isovalent (like Sr 2+ , Ca 2+ , Pb 2+ , Mg 2+ for Ba 2+ and Zr 4+ , Sn 4+ , Mn 4+ for Ti 4+ ) or alio‐valent (like Ta 5+ , Sb 5+ , Nb 5+ , Mn 3+ , Mo 3+ , W 3+ , Fe 3+ for Ti 4+ and Sm 3+ , La 3+ , Pr 3+ , Gd 3+ for Ba 2+ ) in BaTiO 3 lattice can be done for improved properties 1‐5 . Here, in all cases, the cation with extra positive charges present in the dopant ions is compensated by excess electrons, which are assumed to be present in the Ti 3d‐ conduction band.…”

“…Extensive literature review reveals that the improvement in such properties can be achieved with suitable site engineering. Examples of solid solutions include but not limited to those mentioned here: BST, BCT, BZT, (Ba 1− x Sr x )(Ti 1− y Sn y )O 3 (BSTS), (1 − x )Ba(Ti 0.8 Zr 0.2 )O 3 − x (Ba 0.7 Ca 0.3 )TiO 3 [BZT‐BCT] 4‐8,12‐18 …”

“…These include ferroelectric perovskite BaTiO 3 (BTO), BiFeO 3 (BFO), Na 0.5 Bi 0.5 TiO 3 (NBT), K 0.5 Bi 0.5 TiO 3 (KBT), K 0.5 Na 0.5 NbO 3 (KNN), Bi 4 Ti 3 O 12 (BIT) and their solid solutions [BaZr (1Àx) Ti x O 3 (BZT), Ba (1Àx) Ca x TiO 3 (BCT), Ba (1Àx) Sr x TiO 3 (BST), (1 À x)BaZr 0.2 Ti 0.8 O 3 -xBa 0.7 Ca 0.3 TiO 3 (BZT-BCT), (Ba 0.5 Sr 0.5 )(Ti 0.8 Sn 0.2 )O 3 (BSTS), (1 À x) Bi 0.5 Na 0.5 TiO 3 -xBaTiO 3 (BNT-xBTO)] etc. [1][2][3][4][5] Due to their unique combination of properties such as spontaneous and switchable polarization, piezoelectricity, and pyroelectricity, ferroelectricity, electrocaloric effect, photovoltaic effect and photocatalytic properties etc, perovskite-based ferroelectric have been extensively studied for multifunctional applications including nonvolatile random access memories (NVRAMs), dynamic random access memories (DRAMs), high-frequency (GHz) bypass capacitors, infrared detectors, as well as tunable devices in microwave electronics. In particular, ferroelectric materials are very much suitable for energy storage capacitors, multilayer ceramic capacitors (MLCCs), actuators, lead-free piezoelectric transducers, and charge storage devices are particularly popular in power electronics, pulsed power applications, highpower microwave systems etc.…”

Annealing temperature dependence of local piezoelectric response of (Pb,Ca)TiO3 ferroelectric thin films

“…In addition, the influence of doping type on the formation of ferroelectric perovskite materials showed that iron doping induces the disappearance of ferroelectricity in (Pb,Sr)(Ti,Fe)O 3 thin films [8]. Puli et al [9] observed a strong domain switching response at nanoscale level by using PFM in (Ba 0.50 Sr 0.50 )(Ti 0.80 Sn 0.20 )O 3 thin films a. Furthermore, Huang et al [10] reported PFM images in which domain boundaries are in agreement with grain boundaries in Bi 3.15 Nd 0.85 Ti 3 O 12 ferroelectric thin films, suggesting that grain boundaries entirely confine the shape of domain boundaries.…”