The role of stress on the phase evolution of thin-film TiNi has not been investigated and may play an important role in the phase evolution of thin film TiNi. In this paper, a preliminary set of phase diagrams for Ni-Ti at different pressures are presented relating the stability of the stoichiometric TiNi phase to the other well-documented intermetallics TiNi3 and NiTi2. It is found that for sufficient pressure of the order of a GPa, the region where NiTi (β) phase is single phase shifts towards the Ti-rich side of the diagram. The implications on the annealing of TiNi thin film is discussed.

The effect of the elastic energy of internal stresses in a system of coherent phases within an epitaxial layer is considered. The equilibrium two-phase layer has a transversely modulated structure with a modulation period dependent on the layer thickness. The phase diagrams for the phases in an epitaxial layer can differ qualitatively from standard phase diagrams, and this difference also depends on the layer thickness.

The thermodynamics of the formation of a coherent epitaxial two-phase modulated structures from a liquid solution is considered. It is shown that elastic interactions in the epitaxial system change the topologic features of the eutectic phase diagram. As a consequence an eutectic point splits into two eutectic points or it is transformed into a consolute point.

IV-VI semiconductor Pb1−xsSnxsSe1−ysTeys quaternary alloys were grown on (111) BaF2 by liquid phase epitaxy (LPE). X-ray diffraction analysis shows that liquid (Pb1−x1Snx1)0.99(Se1−y1Tey1)0.01 solutions produce alloys lattice-matched with the substrate wheny1 = 60%, 58%, and 57%, and x1 = 20%, 40%, and 60%, respectively. These data suggest that the chemical potential of tellurium in the Pb1−xsSnxsSe1−ysTeys solid solution decreases as tin and tellurium concentrations increase. It is argued that this reduction is due to decreasing strain energy driven segregation of tellurium from the solid to the liquid as the tin concentration increases.

The formation of CoSi2 on Ge.17Si.83 layers by Co/Ge.17Si.83 thermal reaction nas been studied with a variety of analytical techniques. Co films deposited on strained Ge.17Si.83 layers were annealed at 600°C for 0–240 min. Following 240 rain annealing, the reacted surface layer was composed of CoSi, CoSi2 and GexSi1-x precipitates (the latter probably rich in Ge) as identified with transmission electron microscopy, x-ray diffraction and/or Raman spectroscopy. Lateral phase non-uniformity was evident with both transmission and scanning electron microscopy. For samples annealed with and without an evaporated Co film, enhanced relaxation of the underlying Ge.17Si.83 layer was apparent in the former.

Although the thermo-mechanical properties of NiTi are well known for bulk material, its deposition and utilization as a thin film are still in their earliest stages of research. The deposition of thin-films of Shape Memory Effect NiTi onto Si(100) wafers offers several advantages over bulk NiTi, including fast response times and comparatively large transformation forces. This has made it a promising candidate material as micro-actuators for Micro-Electro-Mechanical (MEMS) systems as well as for strain measurements. The cycling time for actuation was measured for a 20 μm free standing NiTi thin film cantilever. It was demonstrated that cycling frequencies of up to 50 Hz are achievable.

Direct observation of the self-accommodation morphology for orthorhombic martensite in Ti51.0Ni44.4Cu4.6 thin films has been accomplished by transmission microscopy of fine grained (<2μm) material prepared by triode magnetron sputtering. The films were observed to undergo, on cooling, two separate thermoelastic transformations in which the B2 austenite phase first transformed to an orthorhombic martensite with a =.291 nm, b =.425 nm and c =.450 nm followed by transformation to the monoclinic phase at lower temperature. The R-phase transformation was suppressed. Single grains contained as many as eight crystallographic variants of the orthorhombic phase, the majority of which were shaped as parallelograms bounded by {111}Ortho twin planes. The local self-accommodation mechanism produced combinations in which three adjacent variants shared a common {111}B2 pole. Although the majority of B19 variant domains accommodated themselves through {111}Ortho type twinning, a second accommodation mechanism, involving two sets of band-like martensite variants, bounded by {011}ortho twin planes, was also observed. Simultaneous occurrence of the {111}ortho and {011}ortho twinning modes, wihtin a single austenite grain, was not observed.

A solid under irradiation is a far-from equilibrium system, and therefore phase equilibria in such a system cannot be assessed from equilibrium thermodynamics. Starting from a kinetic description which incorporates the various processes responsible for atomic diffusion (e.g. thermally activated jumps, replacement sequences or displacement cascades), the various possible steady-states can be identified analytically or numerically, as well as their kinetic evolution on varying the control parameters of the system (e.g. temperature, average composition, irradiation flux, cascade density …). Furthermore, from stochastic versions of the kinetic model, potentials governing the stationary probability distribution of states can be derived, allowing to build dynamical equilibrium phase diagrams.

Illustrating the above approach on the A2-B2 order-disorder transition, we have identified irradiation-induced two-phase state, cascade size and density effects on phase stability. By incorporating point defects, such description is well suited to study irradiation-induced segregation at sinks in concentrated alloys.

In this paper we discuss the size-dependent shrinkage rate of nanometer-size Si crystals in amorphous Si thin films during ion irradiation. We obtain shrinkage rate of nanometersize crystals at low temperature under ion irradiation by studying the evolution of the crystal size distribution using transmission electron microscopy. Our results indicate that crystals less than 10 nm in diameter decrease in size faster than larger crystals under ion irradiation. In addition, we fit our data to a capillary model for growth of Si crystals in amorphous Si under ion irradiation.

The structural analysis of Al layers on Si obtained by sputtering at different conditions and implanted with nitrogen (with doses of 2.5×10'17 and 5×1017 N2+ ions/cm2, energy 150 keV, room temperature) is performed by SRP, SIMS and TEM measurements. The correlation between these measurements shows the formation of AIN crystalline precipitates already at the substoichiometric dose. SRP and TEM reveal the presence of a buried layer with resistivity higher than the Al matrix, with a high concentration of AIN precipitates. The morphology of this layer is affected by surface roughness. For the higher dose, a buried continuous AIN polycrystalline dielectric layer is formed. Moreover, the SIMS measurements suggest a gettering effect of Si in the buried layer.

The Ar-ion-beam-mixing of the FeZr multilayer system is studied by conversion electron Mdssbauer spectroscopy. The dependence of the amorphization process on the layer thickness and ion dose is studied in detail for samples with Fe to Zr ratio of 1 and 0.5 and modulation wavelength of 5 to 90 nm.

The amorphization process induced by ion-beam-imxing was studied for the Zr/Ni bilayer system by means of the RBS/channelling and CEMS techniques. The number of atoms mixed per one incident atom was found to be the same for σ100 K and 300 K irradiations, whereas it was increased by the factor of 2.5 for 500 K irradiation what indicates, that the change in the mixing mechanism occurred above room temperature. The results show that amorphization of the Zr/Ni system is controlled by the number of mixed atoms and depends on the irradiation temperature. A change in CEMS spectra was observed at σ770 K what suggests that recrystallization of the amorphous phase occurs at this temperature.

Atomic transport in irradiated solids has been investigated in both the prompt and delayed regimes. Prompt effects are revealed on an atomic level through molecular dynamics computer simulations. It is demonstrated that for metals like gold, which have high atomic numbers and low melting points, thermal spikes play a primary role in the cascade dynamics and that concepts like melting and rapid quenching are useful descriptions. Surface effects in these metals are also discussed. For metals with higher melting points and lower atomic numbers, the cascade dynamics are determined almost exclusively by energetic collisions far above thermal energies. This is illustrated by simulations of cascades in NiAl. The effect of the high ordering energy in this intermetallic compound on the radiation-induced defect structure has also been studied.

Atomic transport in the delayed regime is illustrated by two examples: an order-disorder alloy, Cu3Au, and an amorphous alloy, NiZr. The first example is used to illustrate various aspects of radiation enhanced diffusion (RED): ion beam mixing, diffusion kinetics, the effects of primary recoil spectrum, and the importance of chemical order. The second example illustrates that the basic theory of RED, which was developed to describe crystalline materials, appears to work adequately for amorphous metal alloys, suggesting that similar mechanisms may be operating. It is shown, however, that the kinetics of RED observed in amorphous alloys are not unique to point defect models.

The dynamics of defect annihilation and creation in amorphous silicon (a-Si) are measured in detail using defect-related changes in the electrical conductivity of a-Si A model is proposed which for the first time can track the complete time evolution of defect population across the activation energy spectrum with explicit dependence on irradiation and annealing parameters. The model is based upon experimental activation energy spectrum, bimolecular recombination kinetics, and on the notion of a maximum density of defect states beyond which no additional defects can be supported. The new model predicts transient dynamics in defect population and describes structure of the defect population in detail. Its predictions are in good qualitative agreement, and in reasonable quantitative agreement with experimental data.

Ion beam mixing of In0.20Ga0.80As quantum well marker layers in GaAs following 1 MeV Kr ion irradiation has been measured as a function of irradiation temperature and fluence. Secondary Ion Mass Spectrometry (SIMS) was used to measure the diffusion of the In0.20Ga0.80As layer following irradiation at various temperatures. Rutherford Backscattering (RBS) and channeling methods were used to determine the extent of the amorphization as a result of the implantation. The mixing parameter of the In0.20Ga0.80As in the GaAs matrix increased from σ120 Å5/eV at 77K to σ160Å5/eV in the temperature range of 300K–450K, but decreased somewhat at 573K. This behavior of In0.20Ga0.80As marker layers will be compared to AlAs marker layers which show similar temperature dependence. These results are interpreted on the basis of thermal spikes and crystal structure.

Titania thin films grown by reactive bias sputtering were characterized. In order to investigate the role of energetic ion on the growth of crystalline phases of TiO2 thin films, we applied substrate biases during deposition. The structural properties were analyzed using X-ray diffractometry (XRD), and related to the optical properties of the films. The atomic composition was determined using Rutherford backscattening spectrometry (RBS).

Negative substrate bias, Vb, showed a significant influence on the phase formed composition and microstructure: Vb in the range of 15 and 60 V enhanced the growth of crystalline phases and the rutile dominated the phase composition. However, the quantity of rutile decreased when Vb was raised to 100 V. The excess of oxygen was shown in the films by RBS.

An in situ study of electron beam irradiation induced amorphous–to–crystalline transformation of Al2O3 films on silicon substrates has been carried out using transmission electron microscopy. Trigonal α–Al2O3 crystallites can be observed for electron beam dose rates larger than 10 mA/cm2. It is found that the nucleation and growth processes dominate near the Al2O3–Si interface. The possible effect of the silicon substrate on the growth of Al2O3 crystallites is considered.

This work presents molecular dynamics simulations of low-energy (40-80 eV) ionbeam mixing of thin metallic hetero-structures. The results indicate that the propagation of the cascade may maintain or even restore crystallinity in disordered interfacial regions.

Titanium silicide and cobalt silicide crystallization and formation reactions are important for the processing of CMOS circuits. We demonstrate that kinetic analysis of these reactions under both high heating rates and isothermal heating conditions allows for the determination of transformation mechanisms. For Ti/Si reactions, we show that the C49 to C54-TiSi2 transformation can not be bypassed using heating rates up to 3000°C/min. For the crystallization of CoSi2 from amorphous Co-Si thin films without ion irradiation, the crystallization kinetics are characterized by three dimensional growth from quickly consumed nucleation sites. With high dose silicon ion implantation of the as-deposited films, the crystallization mechanism changes to homogeneous nucleation and two dimensional growth.

The C49–to–C54 transition in TiSi2 was investigated by resistance measurement and x-ray diffraction technique. The resistance measurement showed that the C49–to–C54 transition has an activation energy strongly dependent on the titanium thickness. The energy increased with the thinning of the TiSi2, from 4.6±0.3 eV for TiSi2 formed with 50nm titanium, to 10.5±0.3 eV formed with 20nm titanium. Furthermore, x-ray diffraction result showed that (004)-oriented phase in C54 TiSi2 is responsible for the increase in activation energy. This orientation dependence of the activation energy probably originates from anisotropy in C54 crystal growth during the transition.