Phase separation during co-deposition of Al–Ge thin films

We present the results of a combined experimental and theoretical investigation of phase separation and microstructure development in co-deposited Al–Ge thin films. For small film thicknesses and deposition temperatures above 150 °C the phase-separated films consist of an array of domains of the Al- and Ge-rich terminal phases (lateral phase separation). Films deposited at 100 °C or less contained one or both of the terminal phases plus a metastable phase. We show that the domain structure evolves during deposition in a manner consistent with a surface interdiffusion controlled process. As film thickness increases we observe a transition from the laterally phase-separated microstructure to a layered microstructure exhibiting phase separation perpendicular to the film/substrate interface (transverse phase separation), with Al segregating to the film surface. We present a thermodynamic argument based on the competition between surface and interfacial free energies to explain this transition. Finally, we discuss the stability of the transverse phase-separated microstructure in the thick-film limit in terms of the transport of Ge through the Al-rich surface layer.

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Exotic Doping for Zno Thin Films: Possibility of Monolithic Optical Integrated Circuit

MRS Proceedings ◽

10.1557/proc-574-317 ◽

1999 ◽

Vol 574 ◽

Cited By ~ 7

Author(s):

Norifumi Fujimura ◽

Tamaki Shimura ◽

Toshifumi Wakano ◽

Atsushi Ashida ◽

Taichiro Ito

Keyword(s):

Thin Film ◽

Thin Films ◽

Nonlinear Optic ◽

Integrated Circuit ◽

Film Surface ◽

Zno Thin Films ◽

Process Window ◽

Electro Optic ◽

Film Substrate ◽

Optical Integrated Circuit

AbstractWe propose the application of ZnO:X (X = Li, Mg, N, In, Al, Mn, Gd, Yb etc.) films for a monolithic Optical Integrated Circuit (OIC). Since ZnO exhibits excellent piezoelectric effect and has also electro-optic and nonlinear optic effects and the thin films are easily obtained, it has been studied as one of the important thin film wave guide materials especially for an acoustooptic device[1]. In terms of electro-optic and nonlinear optic effects, however, LiNbO3 or LiTaO3 is superior to ZnO. The most important issue of thin film waveguide using such ferroelectrics is optical losses at the film/substrate interface and the film surface, because the process window to control the surface morphology is very narrow due to their high deposition temperature. Since ZnO can be grown at extremely low temperature, the roughness at the surface and the interface is expected to be minimized. This is the absolute requirement especially for waveguide using a blue or ultraviolet laser. Recently, lasing at the wavelength of ultraviolet, ferroelectric and antiferromagnetic behaviors of ZnO doped with various exotic elements (exotic doping) have been reported. This paper discusses the OIC application of ZnO thin films doped with exotic elements.

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Void and Dislocation Microstructure Development in Heteroepitaxial Film Growth

MRS Proceedings ◽

10.1557/proc-399-371 ◽

1995 ◽

Vol 399 ◽

Author(s):

Richard W. Smith ◽

David J. Srolovitz

Keyword(s):

Thin Films ◽

Molecular Dynamics ◽

Film Growth ◽

Lattice Misfit ◽

Two Dimensional ◽

Microstructure Development ◽

Non Equilibrium Molecular Dynamics ◽

Dynamics Simulations ◽

Film Substrate ◽

Edge Dislocations

ABSTRACTTwo dimensional, non-equilibrium molecular dynamics simulations have been performed to examine the microstructures of both homoepitaxial and heteroepitaxial thin films grown on single crystal substrates. The principal microstructural features to develop within these films are small voids and edge dislocations. Voids form near the surface of the growing film as surface depressions between microcolumns pinch off to become closed volumes. These voids often form in such a way as to introduce dislocations into the crystal with their cores positioned within the voids. Dislocations are also formed during heteroepitaxy at the interface between the substrate and film. These dislocations tend to be mobile. When voids are present in the film and when the lattice misfit is low, dislocations tend to be trapped in the voids or pulled toward them due to dislocation image interactions. Once attached to voids, dislocations are effectively pinned there. When voids are absent or when the misfit is high, dislocations are restricted to the film-substrate interface. In the case of heteroepitaxy, dislocations are found to relieve either tensile or compressive misfit stresses. Misfit stresses may also be accommodated, to some extent, merely by the free volume of the voids themselves.

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The Effect of Interfacial Free Energies on the Stability of Microlaminates

MRS Proceedings ◽

10.1557/proc-652-y1.3 ◽

2000 ◽

Vol 652 ◽

Author(s):

A. C. Lewis ◽

A. B. Mann ◽

D. van Heerden ◽

D. Josell ◽

T. P. Weihs

Keyword(s):

Electron Microscopy ◽

Grain Boundary ◽

High Temperatures ◽

Free Energies ◽

Microstructural Stability ◽

Creep Tests ◽

Interfacial Energies ◽

Transmission Electron ◽

The Stability ◽

Interfacial Free Energies

ABSTRACTLaminated composites with polycrystalline layers typically break down at high temperatures through grain boundary grooving and the pinch-off of individual layers. Such materials, when exposed to high temperatures, develop grooves where grain boundaries meet the interfaces between layers. The depths of the grooves are controlled by the ratios of grain boundary and interfacial free energies, γgb/γint. Depending on the dimensions of the grains, these grooves can extend through the entire layer, causing pinch-off at the grain boundary. This pinch-off destroys the layering and eventually leads to a gross coarsening of the microstructure. Because microstructural stability is critical to performance for most applications, the ability to understand and predict the stability of microlaminates is a necessary tool. An existing model of this capillarity-driven breakdown requires the interfacial free energies, γgb and γint, as input parameters. Both biaxial and uniaxial zero creep tests have been used in conjunction with transmission electron microscopy to measure these interfacial energies in Ag/Ni and Nb/Nb5Si3 microlaminates.

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Interfacial Free Energies and the Creep of Multilayer Thin Films

MRS Proceedings ◽

10.1557/proc-505-157 ◽

1997 ◽

Vol 505 ◽

Author(s):

D. Josell ◽

W. C. Carter

Keyword(s):

Thin Films ◽

New Technique ◽

Multilayer Thin Films ◽

Free Energies ◽

Creep Properties ◽

Multilayer Foils ◽

A New Technique ◽

Interfacial Free Energies

ABSTRACTExperiments utilizing the creep properties of multilayer thin films to determine interfacial free energies are presented with essential theory. A new technique utilizing tubular multilayer foils is then described.

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Observation of metastable phase separation and amorphous phase in Fe67Co33 alloy thin films synthesized by pulsed laser depositions

Current Applied Physics ◽

10.1016/j.cap.2015.03.001 ◽

2015 ◽

Vol 15 (6) ◽

pp. 717-721 ◽

Cited By ~ 1

Author(s):

G. Hassnain Jaffari ◽

Abdul K. Rumaiz ◽

C. Ni ◽

Emre Yassitepe ◽

M. Bah ◽

...

Keyword(s):

Thin Films ◽

Phase Separation ◽

Amorphous Phase ◽

Metastable Phase ◽

Pulsed Laser ◽

Metastable Phase Separation

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Surface roughening in polymer blend thin films by lateral phase separation: A thermodynamic mechanism

The Journal of Chemical Physics ◽

10.1063/1.4764302 ◽

2012 ◽

Vol 137 (17) ◽

pp. 174901 ◽

Cited By ~ 8

Author(s):

Sam Coveney ◽

Nigel Clarke

Keyword(s):

Thin Films ◽

Phase Separation ◽

Polymer Blend ◽

Surface Roughening ◽

Lateral Phase Separation ◽

Thermodynamic Mechanism

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Temperature dependant structural changes in thin films of random semifluorinated PMMA copolymers

Powder Diffraction ◽

10.1017/s0885715613001073 ◽

2013 ◽

Vol 28 (S2) ◽

pp. S144-S160 ◽

Cited By ~ 5

Author(s):

Dieter Jehnichen ◽

Peter Friedel ◽

Romy Selinger ◽

Andreas Korwitz ◽

Martin Wengenmayr ◽

...

Keyword(s):

Thin Films ◽

Phase Separation ◽

Structural Changes ◽

Bulk Material ◽

Fluorine Content ◽

Film Surface ◽

Phase Behaviour ◽

Side Chain ◽

Side Chains ◽

Polymer Backbone

Semifluorinated (SF) side chain polymers show phase separation between polymer backbone and SF side chains. Due to strong interaction between SF segments the side chains determine the structure behaviour strongly, often resulting in layered structures in which backbones and layers of SF side chains alternate. The interest in this work was directed to find out the dependence of these structures on concentration of SF side chains. Thin films of random copolymers consisting of methylmethacrylate (MMA) and semifluorinated side chain methacrylate (SFMA) segments and with different fluorine content in the perfluoroalkyl side chains (abbreviated as H10F10 and H2F8) were prepared by spin-coating. Phase separation and structure changes were initiated by external subsequent annealing. Corresponding bulk material served as basic information. Generation of ordered structures and variation of film parameters were observed using different X-ray scattering methods (XRR, GIWAXS, and GISAXS). The phase behaviour in bulk is governed by the SF side chain amount and their specific fluorine content which control the self-organization tendency of SF side chains. Additionally, the confinement in thin films generates an orientation of side chains normally to film surface.

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The role of nonlinear substrate elasticity in the wrinkling of thin films

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2012.0422 ◽

2013 ◽

Vol 371 (1993) ◽

pp. 20120422 ◽

Cited By ~ 77

Author(s):

John W. Hutchinson

Keyword(s):

Thin Films ◽

Substrate Stiffness ◽

Modulus Ratio ◽

Compliant Substrates ◽

Wide Range ◽

The Stability ◽

Film Substrate ◽

Film Stiffness ◽

Substrate Elasticity

The role of substrate nonlinearity in the stability of wrinkling of thin films bonded to compliant substrates is investigated within the initial post-bifurcation range when wrinkling first emerges. A fully nonlinear neo-Hookean bilayer composed of a thin film on a deep substrate is analysed for a wide range of the film–substrate stiffness ratio, from films that are very stiff compared with the substrate to those only slightly stiffer. Substrate pre-stretch prior to film attachment is shown to have a significant effect on the nonlinearity relevant to wrinkling. Two dimensionless parameters are identified that control the stability and mode shape evolution of the bilayer: one specifying arbitrary uniform substrate pre-stretch and the other a stretch-modified modulus ratio. For systems with film stiffness greater than about five times that of the substrate the wrinkling bifurcation is stable, whereas for systems with smaller relative film stiffness bifurcation can be unstable, especially if substrate pre-stretch is not tensile.

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Determining Interfacial Free Energies from Creep Experiments on Silver-Iron Multilayers

MRS Proceedings ◽

10.1557/proc-356-357 ◽

1994 ◽

Vol 356 ◽

Author(s):

D. Josell ◽

Z.L. Wang

Keyword(s):

Thin Films ◽

Free Energy ◽

Boundary Diffusion ◽

Interfacial Free Energy ◽

Multilayer Thin Films ◽

Free Energies ◽

Diffusion Controlled ◽

Interfacial Free Energies ◽

Over Time ◽

Microstructural Data

AbstractExperiments were conducted on multilayer thin films to determine the free energies associated with silver/iron interfaces. Creep studies determined the loads for which the multilayers neither shrank nor stretched over time. Microstructural data was used with the zero creep loads in a model for grain boundary diffusion controlled creep in multilayers to determine the interfacial free energy.

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