Critical effect of the bottom electrode on the ferroelectricity of epitaxial Hf0.5Zr0.5O2 thin films

AbstractTraditional strategies for improving piezoelectric properties have focused on phase boundary engineering through complex chemical alloying and phase control. Although they have been successfully employed in bulk materials, they have not been effective in thin films due to the severe deterioration in epitaxy, which is critical to film properties. Contending with the opposing effects of alloying and epitaxy in thin films has been a long-standing issue. Herein we demonstrate a new strategy in alkali niobate epitaxial films, utilizing alkali vacancies without alloying to form nanopillars enclosed with out-of-phase boundaries that can give rise to a giant electromechanical response. Both atomically resolved polarization mapping and phase field simulations show that the boundaries are strained and charged, manifesting as head-head and tail-tail polarization bound charges. Such charged boundaries produce a giant local depolarization field, which facilitates a steady polarization rotation between the matrix and nanopillars. The local elastic strain and charge manipulation at out-of-phase boundaries, demonstrated here, can be used as an effective pathway to obtain large electromechanical response with good temperature stability in similar perovskite oxides.

Download Full-text

The Effect of RuO2/Pt Hybrid Bottom Electrode Structure on The Microstructure and Ferroelectric Properties of Sol-Gel Derived PZT Thin Films

MRS Proceedings ◽

10.1557/proc-493-131 ◽

1997 ◽

Vol 493 ◽

Cited By ~ 8

Author(s):

Seung-Hyun Kim ◽

J. G. Hong ◽

J. C. Gunter ◽

H. Y. Lee ◽

S. K. Streiffer ◽

...

Keyword(s):

Thin Films ◽

Leakage Current ◽

Bottom Electrode ◽

Ferroelectric Properties ◽

Sol Gel ◽

Chemical Solution ◽

Electrode Structure ◽

Solution Deposition ◽

Pzt Thin Films ◽

Chemical Solution Deposition Method

ABSTRACTFerroelectric PZT thin films on thin RuO2 (10, 30, 50nm)/Pt hybrid bottom electrodes were successfully prepared by using a modified chemical solution deposition method. It was observed that the use of a lOnm RuO2Pt bottom electrode reduced leakage current, and gave more reliable capacitors with good microstructure compare to the use of thicker RuO2/Pt bottom electrodes. Typical P-E hysteresis behavior was observed even at an applied voltage of 3V, demonstrating greatly improved remanence and coercivity. Fatigue and breakdown characteristics, measured at 5V, showed stable behavior, and only below 13-15% degradation was observed up to 1010 cycles. Thicker RuO2 layers resulted in high leakage current density due to conducting lead ruthenate or PZT pyrochlore-ruthenate and a rosette-type microstructure.

Download Full-text

Phase transition and piezoelectricity of sol–gel-processed Sm-doped BiFeO3 thin films on Pt(111)/Ti/SiO2/Si substrates

Journal of Materials Chemistry C ◽

10.1039/c4tc02886d ◽

2015 ◽

Vol 3 (9) ◽

pp. 2115-2122 ◽

Cited By ~ 43

Author(s):

Wei Sun ◽

Jing-Feng Li ◽

Qi Yu ◽

Li-Qian Cheng

Keyword(s):

Thin Films ◽

Phase Transition ◽

Sol Gel ◽

Orthorhombic Phase ◽

High Quality ◽

Si Substrates ◽

Bifeo3 Thin Films ◽

Gel Processing

We prepared high-quality Bi1−xSmxFeO3 films on Pt(111)/Ti/SiO2/Si substrates by sol–gel processing and found rhombohedral–orthorhombic phase transition with enhanced piezoelectricity.

Download Full-text

Characterization of Sol Gel Prepared KTN Thin Films and Powders by Raman, XRD, and Thermal Analysis Techniques.

MRS Proceedings ◽

10.1557/proc-718-d4.19 ◽

2002 ◽

Vol 718 ◽

Author(s):

A.A. Savvinov ◽

S.B. Majumder ◽

R.S. Katiyar

Keyword(s):

Thin Films ◽

Thermal Analysis ◽

Sol Gel ◽

Dynamic Effect ◽

Orthorhombic Phase ◽

Analysis Techniques ◽

Perovskite Materials ◽

Wide Range ◽

Thermal Analysis Techniques ◽

And Inversion

AbstractThe renewed interest in KTa1-xNbxO (KTN) mixed perovskite materials is connected with their remarkable dielectric properties in the dilute compositions. KTN thin films with x = 0.35 have been prepared on different substrates by sol-gel technique as well as a set of powders with x = 0, 0.05, 0.1, 0.25, 0.48, 0.65, 0.75, and 1. Properties of the material change drastically with the change of x, because of relaxation of both translational and inversion symmetry due to a static disorder in the Nb distribution and the dynamic effect of a precursor ferroelectric order above Tc. Special attention was paid to the characteristic feature of coupling of the single-phonon state to a two-acoustic-phonon feature through anharmonic terms in the potential function as well as behavior of the TO3 mode which becomes a narrow peak of the first-order scattering in the tetragonal ferroelectric phase and shows a tendency to split below Tc2 in the orthorhombic phase. The wide range of x allows better understanding of dynamic processes in the KTN bulk materials which in turn helps in the studies of thin films. The above mentioned materials were studied using Raman scattering, XRD, and thermal analysis techniques.

Download Full-text

Epitaxial Growth and Anisotropic Dielectric Properties of La-Doped Bi4Ti3O12 Thin Films

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.124-126.177 ◽

2007 ◽

Vol 124-126 ◽

pp. 177-180

Author(s):

Jang Sik Lee ◽

Q.X. Jia

Keyword(s):

Thin Films ◽

Dielectric Constant ◽

Dielectric Properties ◽

Bottom Electrode ◽

Dielectric Constants ◽

The Other ◽

Field Range ◽

Anisotropic Dielectric ◽

Dielectric Nonlinearity ◽

La Doped

To investigate the anisotropic dielectric properties of layer-structured bismuth-based ferroelectrics along different crystal directions, we fabricate devices along different crystal orientations using highly c-axis oriented Bi3.25La0.75Ti3O12 (BLT) thin films on (001) LaAlO3 (LAO) substrates. Experimental results have shown that the dielectric properties of the BLT films are highly anisotropic along different crystal directions. The dielectric constants (1MHz at 300 K) are 358 and 160 along [100] and [110], respectively. Dielectric nonlinearity is also detected along these crystal directions. On the other hand, a much smaller dielectric constant and no detectable dielectric nonlinearity in a field range of 0-200 kV/cm are observed for films along [001] when c-axis oriented SRO is used as the bottom electrode.

Download Full-text

RuO2 Thin Films as Bottom Electrodes for High Dielectric Constant Materials

MRS Proceedings ◽

10.1557/proc-343-511 ◽

1994 ◽

Vol 343 ◽

Author(s):

K. Yoshikawa ◽

T. Kimura ◽

H. Noshiro ◽

S. Ohtani ◽

M. Yamada ◽

...

Keyword(s):

Thin Films ◽

Barrier Layer ◽

Bottom Electrode ◽

High Dielectric Constant ◽

Oxygen Barrier ◽

Metal Diffusion ◽

Diffusion Barrier Layer ◽

High Temperature Processes ◽

Sputter Deposited ◽

High Dielectric

ABSTRACTRuthenium dioxide (RuO2) thin films are evaluated as bottom electrode for dielectric SrTiO3. It was found that a RuO2 (50nm) / Ru (20nm) barrier layer on a Si substrate is effective as an oxygen barrier layer and as a metal diffusion barrier layer for sputter deposited SrTiO3 films at substrate temperature of 450°C. To test suitability for high temperature processes, RuO2/Ru electrodes were annealed in air at 600°C. 100nm-thiick RuO2 was sufficient to prevent oxygen diffusion. After annealing in the same condition, the leakage current of sputter deposited SrTiO3 (150nm) on RuO2(50nm) / Ru(50nm) was 7.6 × 10 −9 (A/cm2) at 2V.

Download Full-text

Resistive Switching Memory based on Silver-doped Chitosan Thin Films

MRS Advances ◽

10.1557/adv.2018.72 ◽

2018 ◽

Vol 3 (33) ◽

pp. 1943-1948 ◽

Cited By ~ 3

Author(s):

C. Strobel ◽

T. Sandner ◽

S. Strehle

Keyword(s):

Thin Films ◽

Resistive Switching ◽

Tin Oxide ◽

Bottom Electrode ◽

Low Cost ◽

Memory Devices ◽

Neuromorphic Computing ◽

Resistive Switching Memory ◽

Switching Behaviour ◽

Switching Memory

AbstractMemristors represent an intriguing two-terminal device strategy potentially able to replace conventional memory devices as well as to support neuromorphic computing architectures. Here, we present the resistive switching behaviour of the sustainable and low-cost biopolymer chitosan, which can be extracted from natural chitin present for instance in crab exoskeletons. The biopolymer films were doped with Ag ions in varying concentrations and sandwiched between a bottom electrode such as fluorinated-tin-oxide and a silver top electrode. Silver-doped devices showed an overall promising resistive switching behaviour for doping concentrations between 0.5 to 1 wt% AgNO3. As bottom electrode fluorinated-tin-oxide, nickel, silver and titanium were studied and multiple write and erase cycles were recorded. However, the overall reproducibility and stability are still insufficient to support broader applicability.

Download Full-text

Significantly enhanced energy storage density of epitaxial Ba0.53Sr0.47TiO3 thin films by optimizing bottom electrode material

Ceramics International ◽

10.1016/j.ceramint.2020.02.184 ◽

2020 ◽

Vol 46 (9) ◽

pp. 13900-13906 ◽

Cited By ~ 3

Author(s):

Xiaopei Zhu ◽

Mengyao Guo ◽

Buwei Sun ◽

Peng Shi ◽

Ming Wu ◽

...

Keyword(s):

Thin Films ◽

Energy Storage ◽

Electrode Material ◽

Bottom Electrode ◽

Energy Storage Density ◽

Storage Density

Download Full-text

Self-Accommodation Mechanisms for Orthorhombic Martensite Formation in Sputtered Thin Films of Thermoelastic Ti(Nicu)

MRS Proceedings ◽

10.1557/proc-311-167 ◽

1993 ◽

Vol 311 ◽

Cited By ~ 4

Author(s):

L. Chang ◽

D. S. Grummon

Keyword(s):

Thin Films ◽

Orthorhombic Phase ◽

Austenite Phase ◽

Simultaneous Occurrence ◽

Transmission Microscopy ◽

Fine Grained ◽

Orthorhombic Martensite ◽

Austenite Grain ◽

Lower Temperature ◽

Accommodation Mechanism

ABSTRACTDirect observation of the self-accommodation morphology for orthorhombic martensite in Ti51.0Ni44.4Cu4.6 thin films has been accomplished by transmission microscopy of fine grained (<2μm) material prepared by triode magnetron sputtering. The films were observed to undergo, on cooling, two separate thermoelastic transformations in which the B2 austenite phase first transformed to an orthorhombic martensite with a =.291 nm, b =.425 nm and c =.450 nm followed by transformation to the monoclinic phase at lower temperature. The R-phase transformation was suppressed. Single grains contained as many as eight crystallographic variants of the orthorhombic phase, the majority of which were shaped as parallelograms bounded by {111}Ortho twin planes. The local self-accommodation mechanism produced combinations in which three adjacent variants shared a common {111}B2 pole. Although the majority of B19 variant domains accommodated themselves through {111}Ortho type twinning, a second accommodation mechanism, involving two sets of band-like martensite variants, bounded by {011}ortho twin planes, was also observed. Simultaneous occurrence of the {111}ortho and {011}ortho twinning modes, wihtin a single austenite grain, was not observed.

Download Full-text

Microstructural Evolution of Epitaxial LiNbO3 Thin Films Derived From Metal Alkoxide Solutions

MRS Proceedings ◽

10.1557/proc-202-439 ◽

1990 ◽

Vol 202 ◽

Cited By ~ 3

Author(s):

Keiichi Nashimoto ◽

Michael J. Cima ◽

Wendell E. Rhine

Keyword(s):

Thin Films ◽

Grain Growth ◽

Single Phase ◽

Sol Gel ◽

Precursor Solution ◽

Epitaxial Films ◽

Metal Alkoxide ◽

High Annealing Temperature ◽

Sapphire Substrates ◽

High Annealing

ABSTRACTThe evolution of the microstructure of sol-gel derived LiNbO3 thin films was investigated to understand the growth of epitaxial films. LiNbO3 films were prepared from a precursor solution of lithium ethoxide and niobium pentaethoxide. Prehydrolysis promoted the development of polycrys-talline LiNbO3 films, whereas nonhydrolysis produced solid-state epitaxial growth of LiNbO3 films on sapphire substrates. Although the films looked smooth after annealing at 400°C, the morphology of the films changed, depending on substrates and precursors, due to grain growth at high annealing temperature. Prehydrolysis of the alkoxides caused a decrease in the temperature at which grain growth occurred, whereas the film prepared from the nonhydrolyzed precursor on a sapphire substrate showed denser texture and contained abnormally large domains that appeared to be single phase.

Download Full-text