A TEM study of microstructures of YBa2Cu3O7−x thin films deposited on LaAlO3 by laser ablation

1991 ◽  
Vol 6 (9) ◽  
pp. 1823-1828 ◽  
Author(s):  
S.N. Basu ◽  
A.H. Carim ◽  
T.E. Mitchell
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Film Thickness ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Misfit Dislocations ◽  
High Angle ◽  
Interfacial Structures ◽  
High Degree ◽  
Periodic Spacing

The microstructures of YBa2Cu3O7−x thin films deposited by laser ablation on single crystal (001) LaAlO3 substrates have been investigated. The orientation of the YBa2Cu3O7−x layer next to the interface is found to be completely c-perpendicular, with a high degree of epitaxy between the film and the substrate. Misfit dislocations, with a periodic spacing of around 13 nm, are present at the interface. Two distinct interfacial structures are seen in these films. At a film thickness of around 400 nm, nucleation of c-parallel grains occurs, leading to a switchover from a c, and, and-perpendicular to a c-parallel microstructure. Amorphous particulates, ejected from the target during processing, lead to the formation of misoriented grains, giving rise to high-angle grain boundaries in the film.

Study of YBa2Cu3O7−x thin films grown on single crystal SrTiO3: Not all high angle grain boundaries destroy Jc

1990 ◽  
Author(s):  
Siu-Wai Chan ◽  
D. M. Hwang ◽  
R. Ramesh ◽  
S. M. Sampere ◽  
L. Nazar ◽  
...  
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Grain Boundaries ◽  
High Angle

Grain Boundaries in Yba2 Cu3O7-δ Thin Films

1989 ◽  
Vol 169 ◽  
Author(s):  
M. Grant Norton ◽  
Lisa A. Tietz ◽  
C. Barry Carter ◽  
Stephen E Russek ◽  
Brian H. Moeckly ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Grain Boundaries ◽  
Weak Link ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Superconducting Films ◽  
High Angle ◽  
Twin Boundaries

AbstractGrain boundaries in YBa2Cu3O7-δ thin films deposited on (001)-MgO by pulsed laser ablation have been characterized using selected area diffraction. In addition to twin boundaries, the presence of both low-angle and high-angle grain boundaries were characteristic of the film's microstructure. The presence of certain grain boundaries may be responsible for the weak-link Josephson behavior observed in small constrictions formed in superconducting films on MgO.

YBa2Cu3O7−x Grain Boundary Weak Links on MgO Bicrystal

1992 ◽  
Vol 275 ◽  
Author(s):  
H. B. Lu ◽  
S. L. Tu ◽  
J. J. Wang ◽  
J. Lin ◽  
T. W. Huang ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Weak Link ◽  
Weak Links ◽  
Artificial Boundaries ◽  
Tilt Boundaries ◽  
Preliminary Study ◽  
High Degree

ABSTRACTThe characteristics of YBa2Cu3O7−x (YBCO) thin films by laser ablation on MgO bicrystals have been investigated. The bicrystals were fabricated by hot pressing two single crystals with the configuration of [001] tilt boundaries. The YBCO films were epitaxial grown with C-axis normal to the both adjacent grains of bicrystals. The FWHM about (005) reflection was 0.4–0.5 degree, indicating the high degree of the oriention for the film with small mosaic spread. Our preliminary study showed that the typical value of Jc on either side of the bicrystal boundary was 0.4–10×106 A/cm2 at 15K, while that across the 10° tilt boundaries was 0.3–9×105 A/cm2 at 15K. These results implied that the artificial grain boundaries effectively weakened the supercurrent, and therefore, the weak-link properties of artificial boundaries were more easily controllable than those of naturally occuring grain boundaries.

Effects of in-plane high angle grain boundaries in YBa2Cu3O7 thin films epitaxially grown on (100) MgO on their physical properties

1997 ◽  
Vol 251 (1-2) ◽  
pp. 74-77 ◽  
Author(s):  
X. Castel ◽  
M. Guilloux-Viry ◽  
J. Padiou ◽  
A. Perrin ◽  
M. Sergent ◽  
...  
Keyword(s):  
Thin Films ◽  
Physical Properties ◽  
Grain Boundaries ◽  
High Angle

Characterization of spray-pyrolized superconducting YBaCuO thin films on single-crystal MgO by transmission electron microscopy

1990 ◽  
Vol 5 (8) ◽  
pp. 1605-1611 ◽  
Author(s):  
S. J. Golden ◽  
H. Isotalo ◽  
M. Lanham ◽  
J. Mayer ◽  
F. F. Lange ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Single Crystal ◽  
Processing Parameters ◽  
Transmission Electron ◽  
Film Substrate ◽  
Mgo Substrate

Superconducting YBaCuO thin films have been fabricated on single-crystal MgO by the spray-pyrolysis of nitrate precursors. The effects on the superconductive behavior of processing parameters such as time and temperature of heat treatment and film thickness were investigated. The superconductive behavior was found to be strongly dependent on film thickness. Films of thickness 1 μm were found to have a Tc of 67 K while thinner films showed appreciably degraded properties. Transmission electron microscopy studies have shown that the heat treatments necessary for the formation of the superconductive phase (for example, 950 °C for 30 min) also cause a substantial degree of film-substrate interdiffusion. Diffusion distances for Cu in the MgO substrate and Mg in the film were found to be sufficient to explain the degradation of the superconductive behavior in films of thickness 0.5 μm and 0.2 μm. From the concentration profiles obtained by EDS analysis diffusion coefficients at 950 °C for Mg into the YBaCuO thin film and for Cu into the MgO substrate were evaluated as 3 × 10−19 m2/s and 1 × 10−17 m2/s, respectively.

Molecular Dynamics Simulation on the Out-of Plane Thermal Conductivity of Single-Crystal Carbon Thin Films

2009 ◽  
Vol 60-61 ◽  
pp. 430-434 ◽  
Author(s):  
Xing Li Zhang ◽  
Zhao Wei Sun ◽  
Guo Qiang Wu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Potential Energy ◽  
Film Thickness ◽  
Single Crystal ◽  
Diamond Crystal ◽  
Dynamics Simulation ◽  
Crystal Direction

In this article, we select corresponding Tersoff potential energy to build potential energy model and investigate the thermal conductivities of single-crystal carbon thin-film. The equilibrium molecular dynamics (EMD) method is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (001), and the non-equilibrium molecular dynamics (NEMD) is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (111). The results of calculations demonstrate that the nanometer thin film thermal conductivity of diamond crystal is remarkably lower than the corresponding bulk experimental data and increase with increasing the film thickness, and the nanometer thin film thermal conductivity of diamond crystal relates to film thickness linearly in the simulative range. The nanometer thin film thermal conductivity also demonstrates certain regularity with the change of temperature. This work shows that molecular dynamics, applied under the correct conditions, is a viable tool for calculating the thermal conductivity of nanometer thin films.

scholarly journals Investigation of growth characteristics and semimetal–semiconductor transition of polycrystalline bismuth thin films

IUCrJ ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Nan Wang ◽  
Yu-Xiang Dai ◽  
Tian-Lin Wang ◽  
Hua-Zhe Yang ◽  
Yang Qi
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Film Thickness ◽  
Single Crystal ◽  
Growth Characteristics ◽  
Metallic Surface ◽  
Zone Model ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Zone Ii

The preferred orientation growth characteristics and surface roughness of polycrystalline bismuth (Bi) thin films fabricated on glass substrates using the molecular beam epitaxy method were investigated at temperatures ranging from 18 to 150°C. The crystallization and morphology were analyzed in detail and the polycrystalline metal film structure-zone model (SZM) was modified to fit the polycrystalline Bi thin film. The boundary temperature between Zone T and Zone II in the SZM shifted to higher temperatures with the increase in film thickness or the decrease of growth rate. Furthermore, the effect of the thickness and surface roughness on the transport properties was investigated, especially for Bi thin films in Zone II. A two-transport channels model was adopted to reveal the influence of the film thickness on the competition between the metallic surface states and the semiconducting bulk states, which is consistent with the results of Bi single-crystal films. Therefore, the polycrystalline Bi thin films are expected to replace the single-crystal films in the application of spintronic devices.

Special grain boundaries in YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 870-871
Author(s):  
L.A. Tietz ◽  
C.B. Carter ◽  
D.K. Lathrop ◽  
S.E. Russek ◽  
R.A. Buhrman
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Mechanical Stability ◽  
Yttria Stabilized Zirconia ◽  
High Angle ◽  
Stabilized Zirconia ◽  
Routine Manner ◽  
Cubic Materials ◽  
Oriented Single Crystal

Much attention has recently been paid to the characterization of twin boundaries in YBa2Cu3O7-x (YBCO). However, in polycrystalline samples other high-angle grain boundaries may have a much more significant effect on, not only the superconducting behavior, but also the chemical and mechanical stability of the material. In the present study, attention has therefore also been focussed on several types of low-angle and high-angle grain boundaries. Such boundaries are frequently found in thin films of this material which are grown on {001}-oriented, single-crystal yttria-stabilized zirconia (YSZ) or magnesium oxide by electron beam co-evaporation of the metals in an oxygen atmosphere. The fact that over most of the substrate these films are oriented epitactically with respect to the zirconia substrate means that these high-angle grain boundaries can be characterized in a relatively routine manner using selected-area diffraction. The high-angle boundaries observed in this study include those produced by 23.5°, 29°, and 45° rotations about [001] and 90° rotations about [100] or [010]. These boundaries are compared to special high-angle grain boundaries in cubic materials.

Charge Transport in Pentacene Thin Film Transistors

2001 ◽  
Vol 665 ◽  
Author(s):  
J. H. Schön ◽  
L. D. Buchholz ◽  
Ch. Kloc ◽  
B. Batlogg
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Single Crystal ◽  
Charge Transport ◽  
Grain Boundaries ◽  
Thin Film Transistors ◽  
Room Temperature ◽  
Nanocrystalline Material ◽  
Hole Mobility ◽  
Grain Sizes

ABSTRACTThe charge transport properties in polycrystalline pentacene thin film transistors is investigated. A potential barrier is formed at grain boundaries due charged trapping states. The influence of such grain boundaries on the hole mobility of the devices is analyzed for different grain sizes, trap concentrations, and carrier densities. The results reveal that room temperature mobilities exceeding 0.5 cm2/Vs can be obtained in thin films with large grains as well as in nanocrystalline material. Consequently, single crystal device limits can be reached also by polycrystalline pentacene thin film transistors.

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