Confined Capillary Stresses During the Initial Growth of Thin Films on Amorphous Substrates

2002 ◽  
Vol 69 (4) ◽  
pp. 425-432 ◽  
Author(s):  
S. P. A. Gill ◽  
H. Gao ◽  
V. Ramaswamy ◽  
W. D. Nix
Keyword(s):  
Compressive Stress ◽  
Film Growth ◽  
Thin Film Deposition ◽  
Capillary Forces ◽  
Film Deposition ◽  
Initial Growth ◽  
Element Analysis ◽  
Ceramic Substrates ◽  
Compressive Stresses ◽  
Amorphous Substrates

Changes in substrate curvature indicating the existence of compressive stress in isolated crystallites are commonly observed during the initial stages of thin film deposition of metals on glass or ceramic substrates. Following the suggestion of Abermann et al. (R. Abermann et al., 1978, Thin Solid Films, 52, p. 215), we attribute the origin of this compressive stress to the action of capillary forces during film growth. As new atomic layers are deposited, the capillary forces acting on atoms near the surface are stored as transformation strains in the bulk of the crystallites. To test this concept, we propose three models for evaluating the capillary strains and their induced compressive stresses in a crystalline. A finite element analysis is performed to show that the model predictions agree well with experimental data.

Stress and microstructure evolution during initial growth of Pt on amorphous substrates

2000 ◽  
Vol 15 (11) ◽  
pp. 2540-2546 ◽  
Author(s):  
M. A. Phillips ◽  
V. Ramaswamy ◽  
B. M. Clemens ◽  
W. D. Nix
Keyword(s):  
Thin Film ◽  
Film Growth ◽  
Microstructural Characterization ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Film Stress ◽  
Ex Situ ◽  
Initial Growth ◽  
Plan View ◽  
Areal Fraction

An understanding of the relationship between stress and the corresponding microstructure at various stages of thin film growth might allow prediction and control of both microstructure and film stress during thin film deposition. In the present study, a combination of in situ curvature measurement and ex situ microstructural characterization was used to make correlations between stress and microstructure for the growth of Pt on SiO2. Plan view transmission electron micrographs of Pt films with average thicknesses ranging from 3 to 35 Å show the evolution of microstructure from isolated islands to a coalesced film, in agreement with models for stress behavior during the early stages of film growth. Quantitative measurements of grain size, island size, and areal fraction covered are extracted from these micrographs and, in conjunction with an island coalescence model, used to calculate the magnitude of the tensile stresses generated during coalescence. The predicted curvature is shown to compare favorably with the measured stresses.

Physical Origins of Intrinsic Stresses in Volmer–Weber Thin Films

MRS Bulletin ◽  
2002 ◽  
Vol 27 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Jerrold A. Floro ◽  
Eric Chason ◽  
Robert C. Cammarata ◽  
David J. Srolovitz
Keyword(s):  
Thin Films ◽  
Film Growth ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Stress Evolution ◽  
Island Nucleation ◽  
Stress Effects ◽  
Compressive Stresses ◽  
Island Coalescence ◽  
Made In

AbstractAs-deposited thin films grown by vapor deposition often exhibit large intrinsic stresses that can lead to film failure. While this is an “old” materials problem, our understanding has only recently begun to evolve in a more sophisticated fashion. Sensitive real-time measurements of stress evolution during thin-film deposition reveal a generic compressive–tensile–compressive behavior that correlates with island nucleation and growth, island coalescence, and postcoalescence film growth. In this article, we review the fundamental mechanisms that can generate stresses during the growth of Volmer–Weber thin films. Compressive stresses in both discontinuous and continuous films are generated by surface-stress effects. Tensile stresses are created during island coalescence and grain growth. Compressive stresses can also result from the flux-driven incorporation of excess atoms within grain boundaries. While significant progress has been made in this field recently, further modeling and experimentation are needed to quantitatively sort out the importance of the different mechanisms to the overall behavior.

scholarly journals A FRACTAL MODEL FOR THE FIRST STAGES OF THIN FILM GROWTH

Fractals ◽  
1996 ◽  
Vol 04 (03) ◽  
pp. 321-329 ◽  
Author(s):  
PABLO JENSEN ◽  
ALBERT-LÁSZLÓ BARABÁSI ◽  
HERNÁN LARRALDE ◽  
SHLOMO HAVLIN ◽  
H. EUGENE STANLEY
Keyword(s):  
Thin Film ◽  
Film Growth ◽  
Dynamical Evolution ◽  
Thin Film Deposition ◽  
Fractal Model ◽  
Film Deposition ◽  
Thin Film Growth ◽  
Small Cluster ◽  
Diffusion Controlled ◽  
Cluster Diffusion

In this paper, we briefly review a model that describes the diffusion-controlled aggregation exhibited by particles as they are deposited on a surface. This model allows us to understand many experiments of thin film deposition. In the Sec. 1, we describe the model, which incorporates deposition, particle and cluster diffusion, and aggregation. In Sec. 2, we study the dynamical evolution of the model. Finally, we analyze the effects of small cluster mobility and show that the introduction of cluster diffusion dramatically affects the dynamics of film growth. Some of these effects can be tested experimentally.

Simplified FEA Models in the Analysis of the Redistribution of Beneficial Compressive Stresses in Welds During Cyclic Loading

2018 ◽  
Author(s):  
B. L. Josefson ◽  
J. Alm ◽  
J. M. J. McDill
Keyword(s):  
Cyclic Loading ◽  
Residual Stresses ◽  
Compressive Stress ◽  
Welding Process ◽  
Plastic Behavior ◽  
Element Analysis ◽  
Compressive Stresses ◽  
Static Contact ◽  
Weld Toe ◽  
Compressive Residual Stresses

The fatigue life of welded joints can be improved by modifying the weld toe geometry or by inducing beneficial compressive residual stresses in the weld. However, in the second case, the induced compressive residual stresses may relax when the welded joint is subjected to cyclic loading containing high tensile or compressive stress peaks. The stability of induced compressive stresses is investigated for a longitudinal gusset made of a S355 steel. Two methods are considered; either carrying out a high frequency mechanical impact (HFMI) treatment after welding or alternatively using low transformation temperature (LTT) electrodes during welding. The specimen is then subjected to a cyclic loading case with one cycle with a tensile peak (with magnitude reaching the local yield stress level) followed by cycles with constant amplitude. A sequential finite element analysis (FEA) is performed thereby preserving the history of the elasto-plastic behavior. Both the welding process and the HFMI treatment are simulated using simplified approaches, i.e., the welding process is simulated by applying a simplified thermal cycle while the HFMI treatment is simulated by a quasi-static contact analysis. It is shown that using the simplified approaches to modelling both the welding process and HFMI treatment gives results that correlate qualitatively well with the experimental and FEA data available in the literature. Thus, for comparison purposes, simplified models may be sufficient. Both the use of the HFMI treatment and LTT electrodes give approximately the same compressive stress at the weld toe but the extent of the compressive stress zone is deeper for HFMI case. During cyclic loading it is shown that the beneficial effect of both methods will be substantially reduced if the test specimen is subjected to unexpected peak loads. For the chosen load sequence, with the same maximum local stress at the weld toe, the differences in stress curves of the HFMI-treated specimen and that with LTT electrodes remain. While the LTT electrode gives the lowest (compressive) stress right at the well toe, it is shown that the overall effect of the HFMI treatment is more beneficial.

CORONENE ORGANIC FILMS: OPTICAL AND SPECTRAL CHARACTERISTICS UNDER ANNEALING TEMPERATURE INFLUENCES

2021 ◽  
pp. 2150081
Author(s):  
ERMAN ERDOGAN
Keyword(s):  
Refractive Index ◽  
Annealing Temperature ◽  
Film Growth ◽  
Low Cost ◽  
Spectral Characteristics ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Optical Bandgap ◽  
Dielectric Constants ◽  
Optical Parameters

In this study, spin coating, which is a chemical film layer thin film deposition method, was used for coronene films that were grown on Si substrates annealed at 325, 350 and 375[Formula: see text]K to examine the impacts on the optical properties of films. This method allows for easy control of the deposition parameters such as concentration, temperature and time as well as enables the film growth at low cost. Optical (UV–Vis) spectral measurements in the wavelength range from 200[Formula: see text]nm to 800[Formula: see text]nm were used to extract the bandgap information and to calculate various optical parameters of the spin-coated coronene films. The electronic transitions on the absorption of photons of suitable energy are of indirect allowed type. The corresponding optical bandgap ([Formula: see text]) was determined. Complex dielectric constants, dissipation factor, optical and electrical conductances and refractive index of coronene films were analyzed as a function of temperature. As the film annealing temperature was increased, the dielectric constants and the refractive index values increased, whereas the optical bandgap and electrical and optical conductivity values decreased.

Thin Film Deposition and Growth Processes by Ionized Cluster Beams

1990 ◽  
Vol 206 ◽  
Author(s):  
I. Yamada ◽  
G.H. Takaoka ◽  
H. Usui ◽  
S.K. Koh
Keyword(s):  
Thin Film ◽  
Cluster Size ◽  
Molecular Beam ◽  
Film Growth ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Atomic Scale ◽  
Cluster Beam ◽  
Film Nucleation ◽  
Cluster Beams

ABSTRACTAtomic scale imaging by STM and TEM of the initial stages of film growth of Ag and Au on graphite substrates indicate that the film nucleation processes are markedly different for ionized cluster beam (ICB) and molecular beam (MBE) deposition. Recent results on measurements of cluster size and formation of epitaxial metal-semiconductor layers by ICB are also discussed.

scholarly journals Role of Terminal Groups in Aromatic Molecules on the Growth of Al2O3-Based Hybrid Materials

2021 ◽  
Author(s):  
Arbresha Muriqi ◽  
Maarit Karppinen ◽  
Michael Nolan
Keyword(s):  
Hybrid Materials ◽  
Film Growth ◽  
Molecular Layer ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Hybrid Films ◽  
Molecular Layer Deposition ◽  
Aromatic Molecules ◽  
Inorganic Thin Films ◽  
Aromatic Components

Hybrid materials composed of organic and inorganic components offer the opportunity to develop interesting materials with well-controlled properties. Molecular Layer Deposition (MLD) is a suitable thin film deposition technique for the controlled growth of thin, conformal hybrid films. Despite the great interest in these materials, a detailed understanding of the atomistic mechanism of MLD film growth is still lacking. This paper presents a first principles investigation of the detailed mechanism of the growth of hybrid organic-inorganic thin films of aluminium oxide and aromatic molecules with different terminal groups deposited by MLD. We investigate the chemistry of the MLD process between the post-TMA pulse methyl-terminated Al2O3 surface and the homo- or hetero- bifunctional aromatic compounds with hydroxy (OH) and/or amino (NH2) terminal groups: hydroquinone (HQ), p-phenylenediamine (PD) and 4-aminophenol (AP). Double reactions of aromatic molecules with the alumina surface are also explored. We show that all aromatic precursor molecules bind favourably to the methyl terminated Al2O3, via formation of Al-O and Al-N bonds and CH4 elimination. While reaction energetics suggest a higher reactivity of the OH group with TMA in comparison to the NH2 group, which could enable the double reaction phenomenon for HQ we propose that the upright configuration will be present so that the organic molecules are self-assembled in an upright configuration, which leads to thicker hybrid films. Interactions between the methyl-terminated Al2O3 with substituted phenyls are investigated to examine the influence of phenyl functionalisation on the chemistry of the terminal groups. Reaction energetics show that phenyl functionalization actually promotes an upright configuration of the molecule, which leads to thicker and more flexible films, as well as tuning the properties of the aromatic components of the hybrid films. We also investigate the interactions between methyl-terminated Al2O3 with new possible MLD organic precursors, hydroquinone bis(2-hydroxyethyl)ether and 1,1'-biphenyl-4,4'-diamine. DFT shows that both aromatic molecules react favourably with TMA and are worthy of further experimental investigation.

scholarly journals Controlling the flux of reactive species: a case study on thin film deposition in an aniline/argon plasma

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
D. Sciacqua ◽  
C. Pattyn ◽  
A. Jagodar ◽  
E. von Wahl ◽  
T. Lecas ◽  
...  
Keyword(s):  
Thin Films ◽  
Film Growth ◽  
Argon Plasma ◽  
Thin Film Deposition ◽  
Deposition Process ◽  
Film Deposition ◽  
Capacitively Coupled ◽  
Low Temperature Plasmas ◽  
Free Films

Abstract The plasma based synthesis of thin films is frequently used to deposit ultra-thin and pinhole-free films on a wide class of different substrates. However, the synthesis of thin films by means of low temperature plasmas is rather complex due to the great number of different species (neutrals, radicals, ions) that are potentially involved in the deposition process. This contribution deals with polymerization processes in a capacitively coupled discharge operated in a mixture of argon and aniline where the latter is a monomer, which is used for the production of plasma-polymerized polyaniline, a material belonging to the class of conductive polymers. This work will present a particular experimental approach that allows to (partially) distinguish the contribution of different species to the film growth and thus to control to a certain extent the properties of the resulting material. The control of the species flux emerging from the plasma and contributing to the film growth also sheds new light on the deposition process, in particular with respect to the role of the ion component. The analysis of the produced films has been performed by means of Fourier Transform Infrared spectroscopy (FTIR) and Near Edge X-ray Absorption Fine Structure spectroscopy (NEXAFS).

Mechanical Stresses During Solid State Amorphization of Zr/Co Multilayers

1994 ◽  
Vol 356 ◽  
Author(s):  
M. Moske ◽  
K. Samwer
Keyword(s):  
Thin Film ◽  
Compressive Stress ◽  
High Vacuum ◽  
Kirkendall Effect ◽  
Film Deposition ◽  
Sudden Increase ◽  
X Ray Diffraction ◽  
Compressive Stresses ◽  
Diffusion Paths

AbstractThin film structures of crystalline Zr and Co, deposited in UHV, are investigated by bending beam technique and by X-ray diffraction. During isothermal annealing and interdiffusion reaction of the thin film double layer and multilayer packages large compressive stresses are generated while an amorphous ZrCo-phase is formed. This can, at first hand, be understood in terms of the Kirkendall effect where Co atoms, as the main moving species, lead to a volume increase of the film beyond the Co interface. The observed change in Zr lattice spacing in accordance with the evolution of mechanical stress indicates that the compressive stress is built up particularly within the Zr layer due to the solution of Co in Zr grains during the initial amorphization reaction. Film structures, having Co already present in the crystalline Zr layer after film deposition, show a decrease in reaction kinetics combined with a lower stress level, indicating that the interdiffusion reaction is depending on the stress state in the Zr grains. At late stages of annealing in high vacuum a sudden increase of additional compressive stress is observed, which could be attributed to the oxidation of Zr, very likely due to the formation of diffusion paths for oxygen through the Co (cap-) layer (Kirkendall voids). Such oxidation behavior was not observed with samples measured in situ in UHV directly after film deposition.

Multiscale Modeling of CdTe Thin Film Deposition Process

2013 ◽  
Vol 1524 ◽  
Author(s):  
Alexey Gavrikov ◽  
Andrey Knizhnik ◽  
Dmitry Krasikov ◽  
Boris Potapkin ◽  
Svetlana Selezneva ◽  
...  
Keyword(s):  
Thin Film ◽  
Film Growth ◽  
Diffusion Processes ◽  
Kinetic Monte Carlo ◽  
Local Environment ◽  
Multiscale Model ◽  
Thin Film Deposition ◽  
Deposition Process ◽  
Film Deposition ◽  
Photovoltaic Properties

ABSTRACTDeposition of semiconductor films is a key process for production of thin-film solar cells, such as CdTe or CIGS cells. In order to optimize photovoltaic properties of the film a comprehensive model of the deposition process should be build, which can relate deposition conditions and film properties. We have developed a multiscale model of deposition of CdTe film in close space sublimation (CSS) process. The model is based on kinetic Monte Carlo method on the rigid lattice, in which each site can be occupied by either Cd or Te atom. The model tabulates the energy of the site as a function of its local environment. These energies were obtained from first-principles calculates and then approximated with analytical formulas. Based on determined energies of each site we performed exchange (diffusion) processes using Metropolis algorithm. In addition the model included adsorption and desorption processes of Cd and Te2 species. The results of the model show that a steady-state structure of the surface layer is formed during film growth. The model can reproduce transition from film deposition to film etching depending on external conditions. Moreover, the model can predict deposition rates for non-stoichiometric gas compositions.

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