A Grease for Domain Walls Motion in HfO2-based Ferroelectrics

2021 ◽  
Author(s):  
Alireza Kashir ◽  
Mehrdad Ghiasabadi Farahani ◽  
Jan Lancok ◽  
Hyunsang Hwang ◽  
Stanislav Kamba
Keyword(s):  
Thin Film ◽  
Domain Walls ◽  
Field Effect Transistors ◽  
Field Measurements ◽  
High Resolution Electron Microscopy ◽  
Polar Regions ◽  
Microscopy Imaging ◽  
Resolution Electron ◽  
Ferroelectric Memories ◽  
Electric Field Measurements

Abstract A large coercive field EC of HfO2 based ferroelectric devices poses critical performance issues in their applications as ferroelectric memories and ferroelectric field effect transistors. A new design to reduce EC by fabricating nanolaminate Hf0.5Zr0.5O2 / ZrO2 (HZZ) thin films is used, followed by an ensuing annealing process at a comparatively high temperature 700 °C. High-resolution electron microscopy imaging detects tetragonal-like domain walls between orthorhombic polar regions. These walls decrease the potential barrier of polarization reversal in HfO2 based films compared to the conventional domain walls with a single non-polar spacer, causing about a 40% decrease in EC. Capacitance vs. electric field measurements on HZZ thin film uncovered a substantial increase of dielectric permittivity near the EC compared to the conventional Hf0.5Zr0.5O2 thin film, justifying the higher mobility of domain walls in the developed HZZ film. The tetragonal-like regions served as grease easing the movement of the domain wall and reducing EC

Crystal Structure of and Defects in the Pentacene Thin Film Phase

2002 ◽  
Vol 734 ◽  
Author(s):  
Lawrence F. Drummy ◽  
Paul K. Miska ◽  
David C. Martin
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Low Voltage ◽  
Field Effect Transistors ◽  
High Resolution Electron Microscopy ◽  
Orthorhombic Symmetry ◽  
Extended Defects ◽  
X Ray Diffraction ◽  
Voltage Electron ◽  
Resolution Electron

The aromatic hydrocarbon pentacene is currently under investigation for use as the active layer in electronic devices such as thin film field effect transistors. We have used X-Ray Diffraction (XRD), Electron Diffraction (ED), Low Voltage Electron Microscopy (LVEM), High Resolution Electron Microscopy (HREM) and molecular modeling to investigate the thin film phase of pentacene. We will report the orthorhombic symmetry and lattice parameters of the thin film phase measured experimentally from these techniques. The structure of extended defects such as dislocations and grain boundaries will influence the electrical and mechanical characteristics of the films. Here we show a direct image of an edge dislocation in the thin film phase and discuss the way in which the lattice accommodates the defect.

Interface structure of face-centered-cubic-Ti thin film grown on 6H–SiC substrate

2000 ◽  
Vol 15 (10) ◽  
pp. 2121-2124 ◽  
Author(s):  
Y. Sugawara ◽  
N. Shibata ◽  
S. Hara ◽  
Y. Ikuhara
Keyword(s):  
Thin Film ◽  
Orientation Relationship ◽  
High Resolution Electron Microscopy ◽  
Electron Beam Evaporation ◽  
Face Centered Cubic ◽  
High Adhesion ◽  
Resolution Electron ◽  
Face Centered ◽  
Relationship Of ◽  
High Degree

A titanium thin film was deposited on the flat (0001) face of a 6H–SiC by electron beam evaporation at room temperature in a vacuum of 5.1 × 10−8 Pa. The Ti film was epitaxially grown on the surface, and the interface between Ti and SiC was characterized by high-resolution electron microscopy. It was found that the structure of the deposited titanium is face-centered cubic (fcc), although bulk titanium metal usually has a hexagonal close-packed or body-centered cubic crystal structure. We believe that the unusual fcc structure of Ti thin film is due to the high adhesion of the film to the substrate and the high degree of coherency between them. The orientation relationship of the fcc-Ti/6H–SiC interface was (111)fcc-Ti//(0001)6H–SiC and [110]fcc-Ti//[1120]6H−SiC. Preliminary calculations indicate that this orientation relationship maximizes the lattice coherency across the interface.

Study of the growth mechanism of highly in-plane aligned α-axis YBa2Cu3O7−x thin films on LaSrGaO4 substrate by high resolution electron microscopy

1996 ◽  
Vol 11 (12) ◽  
pp. 2951-2954 ◽  
Author(s):  
J. G. Wen ◽  
S. Mahajan ◽  
H. Ohtsuka ◽  
T. Morishita ◽  
N. Koshizuka
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Cross Sectional ◽  
Plan View ◽  
Oriented Film ◽  
Resolution Electron ◽  
Average Size

Highly in-plane aligned α-axis YBa2Cu3O7−x thin films deposited on (100) LaSrGaO4 substrates by a self-template method were studied by high-resolution electron microscopy along three orthogonal 〈100〉 axes of the substrate. Plan-view images confirm that the majority of the film preferentially aligns across the entire substrate except for very few misaligned domains with average size 10 nm2. Cross-sectional images along the [100] orientation of YBa2Cu3O7−x reveal that in-plane aligned α-axis YBa2Cu3O7−x is grown on a template layer dominated by c-axis oriented film. This strongly suggests that the in-plane alignment of α-axis YBa2Cu3O7−x thin films on (100) LaSrGaO4 substrates is governed by the different stresses along the b and c axes of the substrate. Cross-sectional images along [001] of the YBa2Cu3O7—x thin film reveal that the 90° domains easily nucleate in the region between α-axis YBa2Cu3O7—x and the YBa4Cu3Ox phase. Cracks along the (001) plane of YBa2Cu3O7−x are found to be due to the large mismatch between the c parameters of the thin film and substrate.

The HREM observation of the boundary between YBCO thin film and substrate

1990 ◽  
Vol 48 (4) ◽  
pp. 96-97
Author(s):  
W. Liu ◽  
Y. G. Wang ◽  
L. Li
Keyword(s):  
Thin Film ◽  
Film Surface ◽  
High Resolution Electron Microscopy ◽  
Ybco Thin Film ◽  
High Critical Current Density ◽  
Cross Sectional ◽  
Face To Face ◽  
Resolution Electron ◽  
Film Substrate ◽  
Substrate Sample

It is a very important problem to obtain high critical current density Jc in high critical temperature Tc superconductors. For high Tc thin film superconductors, the Jc value can reach >106 A/cm2 at 77K. We have prepared YBa2Cu3Oy (YBCO) thin films by magnetron sputtering method, the Jc values ranged from 104 -106 A/cm2, the films were deposited both on (100) SrTiO3 and (100) LaAlO3 substrates. It is well known that Jc is closely related to the microstructure of the film, in this paper we report the observation by high resolution electron microscopy of the boundary between film and substrate and analysis the result with relation to the Jc values of the films.The cross sectional specimens of the film and substrate boundary were prepared by cutting the film-substrate sample into thin slices, then stick the slices with film surface face to face by epoxy resin.

POLAR AND CHEMICAL DOMAIN STRUCTURES OF LEAD SCANDIUM TANTALATE (PST)

1993 ◽  
Vol 07 (09) ◽  
pp. 609-621 ◽  
Author(s):  
JULIN PENG ◽  
L. A. BURSILL
Keyword(s):  
Domain Walls ◽  
Complex Oxide ◽  
High Resolution Electron Microscopy ◽  
Domain Structures ◽  
Type Complex ◽  
Resolution Electron ◽  
A Site ◽  
First Time ◽  
Functional Ceramics ◽  
The Ideal

The local structure of chemical and polar domains and domain walls is determined directly by atomic resolution high-resolution electron microscopy (HRTEM). Thus the Pb, Ta, and Sc atomic positions may be located in the images of very thin crystals. Furthermore, the Pb cation displacements away from the ideal perovskite A-site have been measured directly for the first time. Local variations in polarization direction may be mapped directly off the images, provided certain electron optical conditions are met. The results are relevant to recent theories of polar-glass behaviour in relaxor-type complex oxide functional ceramics.

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