Film/substrate interface stability in thin films

2006 ◽  
Vol 99 (4) ◽  
pp. 043504 ◽  
Author(s):  
R. Krishnamurthy ◽  
D. J. Srolovitz
Keyword(s):  
Thin Films ◽  
Interface Stability ◽  
Substrate Interface ◽  
Film Substrate

scholarly journals Enhanced Ionic Conduction at the Film/Substrate Interface in LiI Thin Films Grown on Sapphire(0001)

1993 ◽  
Vol 318 ◽  
Author(s):  
D. Lubben ◽  
F. A. Modine
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Ionic Conduction ◽  
High Vacuum ◽  
Dislocation Motion ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Substrate Interface ◽  
Interdigital Electrodes ◽  
Film Substrate

ABSTRACTThe ionic conductivity of LiI thin films grown on sapphire(0001) substrates has been studied in situ during deposition as a function of film thickness and deposition conditions. LiI films were produced at room temperature by sublimation in an ultra-high-vacuum system. The conductivity of the Lil parallel to the film/substrate interface was determined from frequency-dependent impedance measurements as a function of film thickness using Au interdigital electrodes deposited on the sapphire surface. The measurements show a conduction of ∼5 times the bulk value at the interface which gradually decreases as the film thickness is increased beyond 100 nm. This interfacial enhancement is not stable but anneals out with a characteristic log of time dependence. Fully annealed films have an activation energy for conduction (σT) of ∼0.47 ± .03 eV, consistent with bulk measurements. The observed annealing behavior can be fit with a model based on dislocation motion which implies that the increase in conduction near the interface is not due to the formation of a space-charge layer as previously reported but to defects generated during the growth process. This explanation is consistent with the behavior exhibited by CaF2 films grown under similar conditions.

Dislocations and Internal Stresses in Thin Films: A Discrete-Continuum Simulation

1999 ◽  
Vol 578 ◽  
Author(s):  
C. Lemarchand ◽  
B. Devincre ◽  
L.P. Kubin ◽  
J.L. Chaboche
Keyword(s):  
Thin Films ◽  
Critical Stress ◽  
Image Force ◽  
Dislocation Dynamics ◽  
Internal Stresses ◽  
Epitaxial Layers ◽  
Free Standing ◽  
Misfit Stress ◽  
Substrate Interface ◽  
Film Substrate

The plasticity of thin films and layers is of considerable technological interest. For instance, the relaxation of internal stresses in semiconducting epitaxial layers has been the object of many studies [1, 2]. This relaxation is usually treated via the concept of critical thickness, the latter being defined as the maximum layer thickness below which dislocations cannot spontaneously move and relax the internal stresses. The various internal stresses present in epitaxial layers (e.g. the misfit and elastic incompatibility stresses at the film/substrate interface and the image force in a free-standing film) can be computed within a continuum frame. However, the way they influence the motion of a dislocation has not yet been computed, even in a approximate manner. An useful approximation that allows treating the boundary condition at the surface of a free-standing film consists of making use of the concept of image dislocation. Then, the critical stress for moving a dislocation in a free-standing film is the same as that of a capped layer of thickness twice that of the film. To date, models and dislocation dynamics (DD) simulations are available that involve several levels of approximation for the treatment of the dislocation/interface and dislocation/surface interactions [3–7]. For reasons that are not clearly understood, however, these models predict critical thicknesses that are systematically larger than the expected ones. The comparison with experiment is, in addition, made difficult because stresses have to be artificially introduced to replace the internal stresses and approximations have to be done to treat the image stresses. In the present work it is shown that it is now possible to fully account for the contribution of the various sources of internal stresses to the critical stress for the motion of a threading dislocation. This is performed numerically with the help of a hybrid code that combines a DD code for the treatment of the dislocation dynamics and a Finite Element (FE) code for the treatment of the boundary conditions. In what follows, several applications of this discrete-continuum model (DCM) to the study of dislocation motion in epitaxial layers are presented. The motion of a dislocation in a thin film is considered, including the image force and successively adding a misfit stress and an elastic incompatibility stress at the film/substrate interface.

Tuning the edge-on oriented ordering of solution-aged poly(3-hexylthiophene) thin films

2020 ◽  
Vol 8 (26) ◽  
pp. 8804-8813 ◽  
Author(s):  
Md Saifuddin ◽  
Mala Mukhopadhyay ◽  
Arindam Biswas ◽  
Lara Gigli ◽  
Jasper R. Plaisier ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Annealing ◽  
Solvent Vapor ◽  
Substrate Interface ◽  
Film Substrate

In solution-aged thin films, edge-on oriented ordering of nanofibers, along the z-direction, extends by thermal annealing, while near the film–substrate interface, it improves by combined solvent vapor and thermal annealing

Microstructures of La1−xAx(A = Ca or Sr)MnO3−δ thin films by liquid-delivery metalorganic chemical vapor deposition

2001 ◽  
Vol 16 (11) ◽  
pp. 3073-3083 ◽  
Author(s):  
Y. Xin ◽  
K. Han ◽  
N. Mateeva ◽  
H. Garmestani ◽  
P. N. Kalu ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Substrate Interface ◽  
Columnar Grains ◽  
Film Substrate ◽  
Metalorganic Chemical ◽  
Liquid Delivery

The microstructure of La1–xAx(A = Ca or Sr)MnO3–δ thin films grown by liquid-delivery metalorganic chemical vapor deposition on (001) MgO and (110)pseudo-cubic LaAlO3 were studied by transmission electron microscopy. The La1–xCaxMnO3–δ thin film on large lattice mismatched MgO exhibited very defective microstructures and consisted of two typical regions. The first region was close to the film–substrate interface and had an epitaxial relationship to the substrate with many differently oriented domains nucleated on the substrate surface. The second region consisted of columnar grains with some degree of texture. In contrast, the smaller lattice-mismatched La1–xSrxMnO3–δ/(110)pseudo-cubic LaAlO3 film had good crystalline quality with highly oriented columnar grains but exhibited complicated dislocation structures. Apart from the misfit dislocations formed at the film–substrate interface, two types of anomalous dislocations with limited contribution to relieving misfit stresses were also observed. One type of dislocation had extra planes in the film and some climbed into the substrate. These dislocations were considered to form from dislocation loops during nucleation of the film. The other type of dislocations had extra planes parallel to the film–substrate interface and glided into the substrate side resulting in a 2° tilt of the film with respect to the substrate. The complicated dislocation configurations present in the sample were related to the complex strain field in the film. The relative strains along the interface measured in the film were heterogeneous. The variations of the strains in the film were related to the local Curie temperature changes and second-order phase transitions of the film.

Enhanced Diffusional Self-Healing of Polycrystalline Thin Films

2005 ◽  
Vol 237-240 ◽  
pp. 524-530
Author(s):  
Eugen Rabkin ◽  
Leonid Klinger
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Initial Distribution ◽  
Self Healing ◽  
Small Surface ◽  
Surface Flattening ◽  
Substrate Interface ◽  
Surface Diffusivity ◽  
Leading Role ◽  
Film Substrate

We considered the flattening of perturbed surface of a thin stress-free polycrystalline film with columnar microstructure deposited on rigid substrate. We show that the mass transport along the film/substrate interface and along the grain boundaries significantly contributes to the overall rate of surface flattening of the film. The diffusion along the film/substrate interface and along the grain boundaries is driven by the capillary stresses in the film. Using the approximation of small surface slopes, we calculated the distribution of capillary stresses in the film, and derived an explicit expression for the temporal behavior of the film topography. The initial distribution of the capillary stresses rapidly relaxes to the steady-state one that does not allow the accumulation of bending strain in the film. For the films with passivated or contaminated surfaces exhibiting reduced surface diffusivity the interfacial and grain boundary diffusion play a leading role in kinetics of surface flattening. The flattening process can be accelerated in this case by several orders of magnitude. The results of our work can be helpful in design of thin films and coatings with enhanced selfhealing capabilities.

scholarly journals YSZ thin films with minimized grain boundary resistivity

2016 ◽  
Vol 18 (15) ◽  
pp. 10486-10491 ◽  
Author(s):  
Edmund M. Mills ◽  
Matthias Kleine-Boymann ◽  
Juergen Janek ◽  
Hao Yang ◽  
Nigel D. Browning ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Boundary Resistance ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Magnesium Doping ◽  
Substrate Interface ◽  
Film Substrate ◽  
Grain Boundary Resistivity

The grain boundary resistance of nano-columnar yttria-stabilized zirconia thin films is almost completely eliminated near the film–substrate interface through substrate induced magnesium doping.

Film Softening Effects of ZrO2 on MoSi2

1993 ◽  
Vol 322 ◽  
Author(s):  
C. M. Czarnik ◽  
R. Gibala ◽  
M. Nastasi ◽  
J. D. Garrett
Keyword(s):  
Thin Films ◽  
Plastic Strain ◽  
Mechanical Behavior ◽  
Crack Length ◽  
Compressive Stress ◽  
Radial Crack ◽  
Dislocation Activity ◽  
Substrate Interface ◽  
Coated Materials ◽  
Film Substrate

AbstractWe have investigated the effect of thin films of ZrO2 on the mechanical behavior of [001] single-crystalline MoSi2. Previous work in our laboratories has shown there to be a 20-40% reduction in hardness in coated samples relative to the corresponding uncoated samples. We now compare fracture around the indentations as a function of thickness. Thicker ZrO2 coatings reduce radial crack length around the indentation through the intrinsic compressive stress at the film/substrate interface. In addition, ZrO2-coated materials tested in compression at 1250°C exhibit approximately twice the plastic strain of uncoated materials, indicating that reduction in hardness is associated with enhanced plasticity from dislocation activity associated with the film/substrate interface.

Influence of Film/Substrate Interface Structure on Plasticity in Metal Thin Films

2001 ◽  
Vol 673 ◽  
Author(s):  
G. Dehm ◽  
B.J. Inkson ◽  
T.J. Balk ◽  
T. Wagner ◽  
E. Arzt
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Dislocation Motion ◽  
Metal Thin Films ◽  
Cu Films ◽  
Substrate Interface ◽  
Transmission Electron ◽  
Curvature Measurements ◽  
Film Substrate

ABSTRACTIn-situ transmission electron microscopy studies of metal thin films on substrates indicate that dislocation motion is influenced by the structure of the film/substrate interface. For Cu films grown on silicon substrates coated with an amorphous SiNx diffusion barrier, the transmission electron microscopy studies reveal that dislocations are pulled towards the interface, where their contrast finally disappears. However, in epitaxial Al films deposited on single-crystalline α- Al2O3 substrates, threading dislocations advance through the layer and deposit dislocation segments adjacent to the interface. In this latter case, the interface is between two crystalline lattices. Stresses in epitaxial Al films and polycrystalline Cu films were determined by substrate- curvature measurements. It was found that, unlike the polycrystalline Cu films, the flow stresses in the epitaxial Al films are in agreement with a dislocation-based model.

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