(NUMBERS
INDICATE PARTICIPANT NUMBER )
The objective of this project is to achieve a complete computational and experimental description of the structure and fundamental properties of crystal/glass interfaces in a series of materials systems which reflect the underlying issues. In particular, the following properties will be investigated:
‡ Spatially-varying atomistic structure and composition
‡ Bonding and electronic structure
‡ Transport properties
‡ Dispersion forces across the interface
‡ Bulk and gradient thermodynamic quantities
The understanding gained will provide the key to solving major problems in a wide range of ceramic and nanostructure materials. The industries which will benefit include the ceramics industry and those which make use of or depend upon components which involve sintering as part of their production cycle.
The research programme is multifaceted, with the key issues (computational, characterisation) being tackled in several alternative ways in parallel. This approach brings to the problem a range of powerful experimental and computational tools in the hands of leading practitioners. It is important to emphasise the unique nature of this partnership. This is not a partnership drawn together because it sees an opportunity. It is a partnership of internationally leading researchers who have together, over several years and at diverse meetings, realised that a scientific challenge exists, and who have been searching for a way to tackle this problem in a coordinated way. If this opportunity is not seized here, it could easily disappear. Consequently, because of this coordinated commitment, the risk to progress is minimal - all the participants are keen to be involved and to contribute.
Progress will be monitored in a number of ways, both by the EU and US coordinators, but particularly by the Steering Committee. A timeline for the delivery of progress reports is given, and these reports will be distributed in a variety of ways and reviewed by the Steering Committee with input from all the individual partners. As is natural with collaborative research, there will also be many informal avenues for monitoring progress, including interactions between partners visiting each others laboratories, presentations at workshops and the exchange of pre-prints of published works. There will also be an annual meeting of the consortium at which progress and planning will be discussed in depth.
Materials to be Studied
The materials to be investigated have been selected because they can be both modelled and studied experimentally at a high level of detail using the expertise of the investigators, and because they cover the fundamental issues that need exploring. Each system also has clear technological relevance. Through the in-depth study of these chosen systems, an understanding applicable to broader classes of materials is expected to emerge. The materials are (a) silicon-based crystals Si3N4, SiC (b) Si-O-N and Si-O-N-(Y,La) intergranular films (c) Si-O-C and Si-O-C-Al intergranular and surface films (d) Si-O-La and Si-O-N-La surface films and (e) grain boundaries in SrTiO3. The partners have enormous experience with these materials, and have the infrastructure and knowledge to carry out a comprehensive study.
Silicon-Based Crystals Si3N4, SiC and Si have in common a native siliceous (SiO2-based) surface layer that is modified by N, C or other impurities and intentional additives. It is now well-established that a nanometre-thick disordered glass film is present at many grain boundaries in polycrystalline Si3N4 and SiC. The induced structure and composition of the glass film has an important role in polycrystalline fracture and creep behaviour. For silicon, the undoped surface native oxide is an indispensable component of microelectronic devices, but is expected to be replaced by higher performance oxides as length scales shrink in future technology. In the search for new gate and DRAM dielectric oxides with high permittivity and low leakage/high breakdown voltage, fundamental understanding of the structure and chemistry induced in the glass layer by the adjacent crystal and their impact on electrical properties has been largely absent.
Silicon Nitride: Si-O-N and Si-O-N-(Y,La) Intergranular Films. Pure silicon oxynitride films are the most basic that can be both experimentally fabricated and ab initio modelled in this system, and will be the starting model system. Note that Si-O-N films do not provide increased fracture toughness in polycrystalline Si3N4, whereas Si-O-N-(Y,La) films represent the simplest rare-earth doped films that do. The enrichment of La in the intergranular film is typically greater than that of Y, providing some advantages for experimental analysis.
In Si3N4-SiO2, the thickness of the glassy film is 1nm ± 1 Å irrespective of the amount of SiO2 present. EELS applied to the glassy film in high purity Si3N4-SiO2 ceramics has shown the chemical composition of the boundary film to be SiNxOy with x = 0.53 and y = 1.23 indicating that the anion concentration in the silicon oxynitride film is x/(x+y) = 30%.
The constancy of the film thickness and composition is truly remarkable. The fact that the thickness and composition of the film depend only on the composition of the sintering aid, and not on the amount of the sintering aid, indicates that the film exists as a consequence of chemical equilibrium. In other words, in Si3N4-SiO2 ceramics the film is a consequence of equilibrium segregation of oxygen to grain boundaries. The observation that the film thickness and composition are nearly independent of the boundary plane and misorientation indicates that these geometric variables do not strongly affect the equilibrium condition. There are then only 3 primary thermodynamic degrees of freedom governing the equilibrium of the glassy film. For example, once the temperature, pressure and chemical potential of oxygen (i.e. partial pressure of O2) have been specified then the film thickness and composition are uniquely determined in Si3N4-SiO2 ceramics.
In addition, the availability of large single SiC crystals (e.g., from Cree Inc.) allows the study of controlled-misorientation bicrystals. Bulk and thick-film (100 nm) silicon oxycarbide glasses have been synthesized from polymer precursors, and are stable at compositions/temperatures clearly not allowed by bulk phase equilibria. Thus this system is also well-suited to the study of amorphous films of kinetically-stabilized, nonequilibrium compositions. P9 and colleagues will prepare sol-gel films on single crystal SiC of equilibrium and nonequilibrium Si-O-C and Si-O-C-Al compositions. These typically have thicknesses well beyond the range of interest for a grain boundary. However, by lithographically grooving the single crystal surface to provide local reservoirs for excess glass, a bicrystal sandwich of controlled misorientation can be brought to the nanometre-scale separations representative of intergranular glass films in polycrystals. This experimental configuration will be developed by P9 and colleagues. In addition, thinner films of oxycarbide glasses can be deposited by PVD techniques (magnetron sputtering, laser ablation) from SiC/SiO2 targets if necessary, and bicrystals prepared by pressure-welding.
Grain Boundaries in SrTiO3. Strontium titanate is of interest as a non-silicate system that also represents a broad range of complex perovskites of interest for their ferroelectric, dielectric, magnetoresistive, and superconducting properties. Perhaps the most compelling reasons for its inclusion here as a model system are the observations of a wetting transition in polycrystals sintered with titania excess producing eutectic liquid, the transition temperature furthermore being dopant-sensitive, and the existence of amorphous intergranular films in silicate-free boundaries. These pieces of data suggest that a systematic progression from dry to moist (multilayer-adsorbed) grain boundaries to boundaries fully-wetted by a titania-rich eutectic liquid occurs in strontium titanate. The atomic structure and composition of various special boundaries in SrTiO3, with and without dopants, have recently been experimentally characterized and modelled at several laboratories. Here our goal will be to identify whether and where multilayer adsorption and wetting transitions occur, and to understand the criteria for such transitions.
The proposal presented here is innovative in that it brings together international experts with expertise in three different areas - modelling, growth and characterisation - in a coordinated program of research to solve a materials problem. The rationale for specific experiments is discussed later with respect to each materials system. Particularly innovative is the cooperation of computational experts across the length scales of computational modelling. At this point, it will assist the reader to give an overview of the collaborative modelling approach. Every intergranular film has several length scales. Modelling the behaviour of thin films requires cooperation and communication between modellers whose expertise lies in a particular length scale. P7 and P2 will produce ab initio energy calculations in silicate-based and strontium titanate films. These calculations will be compared to experimental ELNES data by P4 and P11 and to experimental REELS (reflection electron energy loss spectroscopy) data by P3 and to electron diffraction structural determinations by P1. P7 will produce calculations of nanometre and interfacially resolved electronic excitations that can be compared directly to ELNES. P7 and P2 will investigate modelling predictions of thermal conductivity and optical excitation that can be used to guide or interpret experiments in specific systems. The ab initio calculations will provide input potentials for molecular dynamic potentials by P8. The P8 results should determine whether a stable amorphous film can be simulated from the input potentials and whether any additional structure can be inferred in stabilized films. From stable amorphous film results, data for composition profiles and induced structural order from the abutting crystalline phases can be obtained. Such structural and compositional order will be reduced to bulk thermodynamic quantities by P6 and then modelled as a continuum thermodynamic system as a phase field model. The phase field models will give predictions of stable film behaviour on a relatively small set of physical parameters and thus allow general predictions to be made and tested against specific experimental results.
This research programme has a workplan with 11 workpackages (see Table 1) which run simultaneously. Because of the complexity of the topic, leading international researchers are essential and the workpackage leaders come from the EU and the US (and so the application is under the EU-US Agreement).
Each of the leaders is an international expert in their field, and each comes with a team of colleagues who will provide intellectual support to each workpackage. The details of the workpackages and their defined objectives and verifiable deliverables are given below in dot point form, and a flow diagram showing their interactions is shown in Figure 1. This is the most succinct way to explain the interactions.
Objectives:
(a) Characterize the structure of amorphous phases of ZnO- Bi2O3, SrTiO3 and silicon-based systems (Si3N4, SiC) in the studied materials
(b) Characterize the structure of the interfaces in the studied systems using HREM techniques
(c) Use the structures derived to refine against the model systems developed in the computational parts of the workplan
Verifiable deliverables
(a) Publication of the structures in (a)
(b) Agreement of the experimental data with model outcomes
W2 Ab initio Computations of Interface Structures
Objectives:
(a)
Grand Canonical Simulations of Silicon Oxynitride Films
(b) Development of bond order potentials for silicon oxynitride systems
Verifiable Deliverables
(a) Paper submitted for publication
(b) Comparison with experimental data
W3 Surface Analysis
Objectives
(a) Use REELS (Reflection Electron Energy Loss Spectroscopy), XPS and UPS (X-ray and UV photoelectron spectroscopy) to derive the electronic structure of very thin films of interest in the proposal, such as Si-La-O and SrTiO3, using currently available samples.
(b) Characterize the chemical bonding in the very thin Si-La-O amorphous films, compared with pure SiO2 and bulk glass phases.
(c) Determine the surface electron energy loss function of thin amorphous layers by REELS.
Verifiable deliverables
(a) publication of results
(b) comparison with VUV optical measurements and EELS experiments, as well as electronic structure calculations.
W4 Electron Energy Loss Spectroscopy and Fine Structure
Objectives
(a) Measurement of electron energy loss spectra with high spatial and energy resolution
(b) Measurement of fine structure of electron loss edges of different elements (ELNES investigation)
(c) Calculate the fine structure by appropriate theoretical models
(d)
Characterize
the structure of interfaces by high-resolution transmission electron
microscopy
Verifiable Deliverables
(a) Papers submitted for publication
(b) Determination of agreement between results from theoretical studies and experimental investigations
W5 Materials Growth and Testing
Objectives
(a) To process Si-N ceramics as in (a) below.
(b) Analyse growth kinetics and influence of film composition on growth morphology.
(c) Determine macroscopic properties as in (c) below.
Verifiable Deliverables
(a) Samples with different intergranular films for the electron
microscopy groups.
(b) Experimental data of the influence of the intergranular film
composition on growth morphology and growth kinetics and agreement with
the model outcomes.
(c) Agreement of experimentally determined macroscopic properties,
measurements of interfacial bonding with the electronic structure
modelling.
W6 Phase Field Modelling of Stable Interfacial Films
Objectives:
(a) To develop a continuum thermodynamic framework for the prediction
and catagorization of stable thin interfacial films.
(b) To develop a method of coarse-graining direct structural
measurements or molecular simulation to obtain self-consistent input
parameters of phase field models.
(c) To classify thin film behavior on the basis of relatively few
thermodynamic parameters.
Verifiable Deliverables:
(a) Publication of a quantitative theory for interface phase structure
and composition.
(b) Demonstrated and articulated technique for obtaining
parameters from data that is self consistent.
W7 Electronic Structure and Spectroscopic Properties
Objectives
Verifiable Deliverables
1. Publications of the work described above.
2. Provision of useful parameters from ab-initio calculations for MD simulation and continuum-scale modelling.
3. Provision of theoretical database of band structures, ELNES spectra (fingerprints), optical properties etc. for materials characterization and experimental interpretations.
4. Development of new and robust methods in computational materials theory.
W8 Molecular Dynamics Simulations of Multicomponent Systems
Objectives:
(a) MD simulations of the surface and interface structure of the amorphous oxide films on Si3N4, SiC, and SrTiO3 and the effect of additives in the amorphous films on structure.
(b) Simulations of transport properties of ions in the amorphous phase as a function of composition.
(c) Simulations of contact between dissimilar crystal orientations in contact with the same intergranular film.
(d) Comparison of all results with ab-initio calculations of local structures and available experimental data for refinement of the potentials.
Verifiable Deliverables:
(a) Publication of data
(b) Refinement of interatomic potentials
W9 Preparation and Characterisation of Surface Films
Objectives
(a) Prepare films of oxycarbide and oxynitride compositions and heat treat.
(b) Determine temperature and composition dependence of above on film thickness.
(c) Characterise film morphology, composition and structure
(d) Determine electrical properties
Verifiable Deliverables
(a) Publication of results as in 1-4 of WP9.
(b) Supply of samples to other WPs.
W10 Interparticle Forces and Wetting
Objectives
(a) Determine surface electronic structure of thin films, by using REELS, XPS and UPS.
(b) Characterize the chemical bonding in the very thin amorphous films (e.g. Si-La-O), compared with pure SiO2 and bulk glass phases.
Verifiable Deliverables
(a) Compositional characterization of surface films
(b) REELS data on surface films
W11 Spatially resolved Measurements of Electronic Structure and Dispersion Forces
Objectives
a) Determine electronic structure of the bulk silicon based systems Si, SiC an Si3N4 using VUV spectroscopy and Ellipsometry, using currently available samples.
b) Determine electronic structure of the bulk strontium titanate using VUV spectroscopy and Ellipsometry using currently available samples.
c) Determine electronic structure of the bulk silicon based systems Si, SiC an Si3N4 using VEELS microscopy, using currently available samples.
d) Determine electronic structure of the bulk strontium titanate using VEELS microscopy using currently available samples.
e) Survey current literature data on optical properties and electronic structure and where necessary update results of reference materials to permit accurate calculations of full spectral Hamaker constants.
f) Determine spatially resolved electronic structure and optical properties for intregranular and surface films in the silicon based materials system for the determination of full spectral Hamaker constants for the London dispersion forces.
g) Determine spatially resolved electronic structure and optical properties for intergranular and surface films in the strontium titanate based materials system for the calculation of full spectral Hamaker constants for the London dispersion forces.
h) Develop quantitative analysis of surface reflection valence electron energy loss spectroscopy of silicon or strontium titanate bulk system.
Verifiable Deliverables
(a) Publication of bulk optical properties and electronic structure of the reference silicon and of strontium titanate systems. Objectives a,b,c, or d
(b) Publication of the optical properties and electronic structure of an intergranular films in the silicon nitride or strontium titanate system. Objective f or g
(a) To manage the EU partnership and to coordinate with US coordinator.
(b) To seek exploitation opportunities
(a) Successful outcome of programme.
(b) Reports to EU.
FIGURE 1
FLOW DIAGRAM SHOWING FLOW OF OUTPUTS AND COMPARISONS
(NUMBERS
INDICATE PARTICIPANT NUMBER )
 |
Theory Workplan
P2 and colleagues will conduct ab initio modelling of the thickness and composition of silicon oxynitride films sandwiched between 2 misoriented Si3N4 grains, beginning with Si-O-N compositions. In previous work P7 and P4 fitted effective interatomic potentials of ionic forms to ab initio calculations of the ground state total energies of a- and b-Si3N4 crystals. These potentials used ionic charges obtained from the ab initio calculations, and were therefore not transferable to other chemical environments where different ionic charges may be expected. The 4 crystalline phases of Si3N4 were modelled with ab initio methods recently by P7 and coworkers. A number of investigators carried out discrete variational X-a calculations on Si-O-N clusters to interpret features that appear in the ELNES spectra from the silicon oxynitride boundary films. They proposed an atomic model for the film, in which there were no dangling bonds. However, to date no simulations of the boundary film in Si3N4-SiO2 ceramics have treated the problem as one involving the establishment of chemical equilibrium through segregation of oxygen to the grain boundary. Since experiments indicate that the oxynitride films are a result of thermodynamic equilibrium we believe that any credible model must guarantee this explicitly.
A variety of ab initio codes are available to P2 including in-house localised-orbital DFT code that is ideally suited to this system. P2 have unique expertise in the construction of bond-order potentials. P2 also has a long track-record in simulating interfaces.
Simulated structures will be compared with the determination of local structure in the silicon oxynitride films by P1 and coworkers using novel electron diffraction techniques which give the pair correlation function. Experiments to examine differences in higher order correlation functions will be carried out. High resolution EM of the interface (crystalline component) will be performed by P1 and coworkers and P4 coworkers. Once the atomic structure is well-established, P7 will use the orthogonalized linear combination of atomic orbitals (OLCAO) method based on density functional theory to calculate the electronic structure. Comparisons of the calculated electronic structure with experiment will be through electron-energy loss near edge spectra (ELNES) spectra. Recent results using supercells and including core-hole effects have shown the predictive power of ELNES calculations. Here, ELNES calculations of the oxynitride films will be compared with experimental measurements on model grain boundaries by P4 and P11.
P8 will carry out molecular dynamics (MD) simulations using variable charge and fixed charge multibody interatomic potentials. Large scale atomistic systems relevant to intergranular films will be simulated in conjunction with the electronic structure calculations and the continuum-level phase field calculations. Two of the major benefits of current MD simulations are: a) the ability to study relatively large system sizes such that relatively large coherence lengths can be included, and b) the ability to incorporate experimentally important variables such as time, temperature, and pressure effects into the simulations such that thermodynamic and kinetic behavior can be determined.
The MD simulations will be used to create intergranular films and interface structures of the oxides on each of the aforementioned crystals as a function of crystal orientation and film compositions in a manner similar to that used experimentally. That is, high temperatures can be used to create a melt state from which the system is cooled to create the resultant crystal/glassy film/crystal interfaces. Kinetic effects on the film structure and chemistry may thereby be revealed. Local structures generated from the MD simulations can be used in electronic structure calculations in order to evaluate the simulation results or be used as a feedback for optimizing the interatomic potentials used in the simulations. The link between theory and experiment will again be through ELNES calculations by P7, applied to the MD simulated atomistic configurations and compared to experimentally determined ELNES data. Interfacial energies will also be obtained from the simulations and compared to sufficiently large size DFT calculations (where system size can affect such energies) and used in the diffuse interface calculations by P6.
Another important aspect of the MD simulations is the study of transport properties. The migration of species in the molten films can be evaluated in the simulations. The effect of interface trapping or channeling by the ordered interface structure can be evaluated as a function of crystal orientation and composition in the simulations.
Experimental Workplan
In the experimental program, P5 will fabricate reference-standard quality high purity Si3N4-SiO2 polycrystals, thermally equilibrated at high temperatures, for electron microscopy and spectroscopy by P1 and colleagues, P11 and P4. Each of the experiments will provide results which can be directly compared with the calculations.
P1 and colleagues, and P4 will characterize the following crystallographic key-quantities as accurately as possible in a series of grain boundaries for collective study:
Orientation relationship of the adjacent crystals; Orientation relationship and faceting statistics of the interfaces between volume crystals and interfacial phase ( internal surfaces with respect to the crystal); High-precision assessment of the thickness of the interfacial phase; Atomistic structure of the terminating crystal planes next to the amorphous films, including possible steps, reconstructions, self-similarities of apparently random fluctuations along the interfaces; Sub-nm localized examination of the terminating layers of amorphous materials, with respect to crystal-surface induced extra ordering mechanisms; Full structural solution including all (relaxed) atomic coordinates and identification of the interface core structure for reference segments of grain boundaries without (or with partially absent) amorphous films;
They will make use of several new problem-adapted techniques, which have not yet been available for major previous HREM studies of interfacial films in ceramic materials, anisotropic Fourier spectral analysis of sub-nm sized interfacial segments; geometric phase holography for the sub-0.1nm tracking of displacements to be converted into 2D-strain maps; detection/rejection of suspected partial order in apparently amorphous films; focal series evaluation to obtain the aberration-free projected electron wave at the bottom side of the specimen, which reveals more reliably the atomic structure; iterative structure refinement to detect relaxations out of a (first guess) reference structure by P7 simulated to experimental images heading for the best fitting structure;.
P1 will use primarily energy-selected electron diffraction to attempt a detailed structural determination of the intergranular glassy phases within these boundaries. Energy selected electron diffraction is now well-established as a means for studying the structure of small volumes of amorphous material. The technique gives the pair correlation function to high accuracy (0.02A first nearest neighbour), which provides a fingerprint for differentiating between possible structural models. However, for studies of intergranular phases, further refinement of the technique will be required, because, to obtain the small size of electron probe necessary to analyse material of the dimension of the intergranular phase, a highly convergent probe will be needed. Pilot studies have shown that deconvolution of the probe function from the diffraction pattern can be achieved satisfactorily.
EXELFS can be used to give the pair correlation function for specified atomic species, and this technique will be used to give results for comparison with the energy selected diffraction results described above.
P4 will obtain ELNES data from the intergranular films for comparison with calculations and P11 will carry out spatially-resolved dispersion force measurements. P10 and colleagues have previously conducted low and high temperature crack growth and creep experiments, and fracture toughness and indentation-based crack deflection measurements on polycrystalline silicon nitride. These measurements will be carried out in parallel and will compare the model materials of this study with each other and with other (generally more complex) doped systems.
A goal in this project will be to determine whether disordered Si-O-La and Si-O-N-La surface films can be stabilized on silicon, the extent of order (if any) in such films, and the correlation between order and electrical properties. These film compositions are both interesting as alternative gate oxides, and will be studied in relation to silicon nitride. Both equilibrium and nonequilibrium compositions are of clear interest given the low processing temperatures typical in silicon microelectronics; nitrogen is of interest as a dopant since it may suppress crystallization by raising viscosity. Amorphous SiO2 is known to dewet silicon grain boundaries, and it may be that native SiO2 surface films are largely kinetically-stabilized. However, as in the case of surface melting and stabilization of surface amorphous films in binary oxides, crystallization may be suppressed if the resulting crystalline heterointerface has high energy. At present, it is not known if equilibrium-thickness amorphous films can be stabilized at silicon free-surfaces. In the first stage of this effort, P9 and colleagues will prepare thin (1-5 nm) Si-O-La and Si-O-N-La films on silicon using magnetron sputtering or laser ablation facilities available to us, and use TEM to characterize wetting/dewetting and crystallization as a function of film composition, thickness, and temperature. Stable films and those exhibiting varying degrees of order will be further studied. The permittivity, breakdown voltage, and leakage current will be measured in order to correlate film structure and composition with electrical parameters. More detailed study of specific stable films will follow by other team members, using the theoretical and experimental techniques discussed earlier. In particular, these oxide films will be studied by P3. First, the composition will be measured by XPS. In addition, the modifications of electronic structure induced by the presence of La, Zr compared to SiO2, will be studied by XPS and REELS, with a special emphasis on the changes of the ionic charges, induced gap states etc. The experimental REELS data will be compared with the VUV data obtained by P11, so as to separate surface/bulk effects. The experimental electronic structure will be compared with the electronic structure calculations of P7.
The higher conductivity of Si relative to Si3N4 facilitates use of methods such as XPS and grazing-angle synchrotron X-ray scattering (to observe ordering and gradients in order. Especially in the Si-O-N-(La,Y) case, structural order in the surface film may be induced by heat treatment.
P10 will conduct grain boundary penetration experiments in which bicrystals of known misorientation (available as substrates for high Tc films) will be heat treated in contact with pre-equilibrated titania rich melts at various temperatures. PbO and Bi2O3 dopants will be studied; the former is known to lower the wetting transition temperature. Silicate additions will be used to affirm that the transitions are not due to impurities. The bicrystal specimens will be characterized by P4 using TEM and STEM in order to determine whether adsorption and wetting transitions do occur, and their dependence on misorientation, temperature, and doping. It is expected that a clear experimental determination of the composition and structure of the Ti-enriched intergranular film will provide the impetus for modelling and additional experiments amongst the collaborators, as in the case of the other materials systems.
A complementary set of experiments will explore the colloidal behavior of Si3N4 particles suspended in appropriately doped silicon oxynitride liquids, and of SrTiO3 particles suspended in variously doped liquids of SrTiO3-TiO2 eutectic. These experiments reveal the degree to which particles are attracted or not and provide a complement to the observations of wetting versus multilayer adsorption from polycrystalline samples. Composition or temperature induced changes of behavior should reveal wetting transitions for the grain boundaries. Samples will be provided for quantitative TEM to P4 or P1.
WP5 is divided into three parts. In the first part P5 will prepare silicon nitride ceramics by liquid phase sintering with different rare earth oxides. Densification will be achieved by a sinter-HIP-process which offers the possibility to use only small quantities the of rare earth additives (2-4 wt.%). The sintering additives are selected with regard to the ionic radius and the electronic structure. Dense microstructures could be further modified by a variation of sintering temperature and time. A special technique developed in the laboratory of P5 enables the shrinkage to be followed and the densification mechanisms to be analysed. By using this technique P5 can optimize the sintering program for a complete densification of silicon nitride with only 2 wt.% Y2O3 and obtain one of the most creep resistant silicon nitride ceramics. The prepared samples will be distributed to WP1 and WP4.
In the second part, P5 will study the influence of the sintering additives on the growth morphology of the silicon nitride grains. The grain impingement during the growth in a ceramic microstructure requires the design of model experiments. P5 will dissolve a small quantity of silicon nitride grains in an oxynitride glass with a similar composition as the grain boundary phase in a ceramic. However the processing conditions of these supersaturated oxynitride glasses require the use of more than one additive. Beside the analysis of the growth kinetics and morphology P5 will also determine with these types of samples the interfacial energy between the glass and a silicon nitride grain. A detailed analysis of the interface between the glass and silicon nitride will be performed by the microscopy groups.
The third part of the workpackage WP5 is the microscopic and macroscopic characterization of the ceramics. P5 will characterize the grain size and grain morphology of the ceramic material by using scanning electron microscopy. The mechanical properties will be characterized on larger specimens including the strength at room as well as at high temperatures. Fracture toughness will be measured by the SEVNB method. Creep behaviour will be measured. The data of the mechanical properties will be then correlated with the results of the microscopy workpackages.
Table 2 shows the deliverables in terms of reports.
An anonymous tabular overview of the consortium composition is shown in Table 3, as required.
A manpower bar chart is included in Table 4, as required.
An overview of Project Milestones with decision criteria is included as
Table 5, as required
Conclusion
This application brings together a team of international EU and US
researchers with expertise in modelling, characterization and growth to
tackle a problem of fundamental importance to both the scientific
community and materials technology. Each of the participants has
extensive experience in the field, access to a wide range of
infrastructure and vibrant research groups. Such a wealth of experience
and resources is difficult to bring together, and it is hoped that this
opportunity to contribute to the programme on Competitive and
Sustainable Growth will not be missed.
END TEXT
TABLE 1
WORKPACKAGES
IDENTIFIER |
WORKPACKAGE |
LEADER |
EU/US |
W1 |
STRUCTURAL CHARACTERISATION OF INTERFACES BY HREM AND ED |
1 |
EU |
W2 |
AB INITIO COMPUTATIONS OF INTERFACE STRUCTURE |
2 |
EU |
W3 |
SURFACE ANALYSIS |
3 |
EU |
W4 |
ELECTRON ENERGY LOSS SPECTROSCOPY AND FINE STRUCTURE |
4 |
EU |
W5 |
MATERIALS GROWTH and TESTING |
5 |
EU |
W6 |
CONTINUUM PHASE FIELD MODELLING |
6 |
US |
W7 |
ELECTRONIC STRUCTURE AND SPECTROSCOPIC PROPERTIES |
7 |
US |
W8 |
MOLECULAR DYNAMICS SIMULATIONS OF MULTICOMPONENT SYSTEMS |
8 |
US |
W9 |
PREPARATION OF SURFACE FILMS |
9 |
US |
W10 |
INTERPARTICLE FORCES AND WETTING |
10 |
US |
W11 |
SPATIALLY RESOLVED MEASUREMENTS OF ELECTRONIC STRUCTURE AND DISPERSION FORCES |
11 |
US |
TABLE 2
OVERVIEW OF GLOBAL DELIVERABLES
Deliverable No |
Delivery Date |
Output from W.P Nr |
Nature of Deliverable and brief Description |
D1 |
M6 |
1-12 |
Report |
D2 |
M12 |
1-12 |
Report |
D3 |
M18 |
1-12 |
Mid-Term Report |
D4 |
M24 |
1-12 |
Report |
D5 |
M30 |
1-12 |
Report |
D6 |
M36 |
1-12 |
Final Report |
TABLE 3
CONSORTIUM OVERVIEW (ANONYMOUS)
Participant Activity Code Nr |
Nr |
Country |
Main Mission/Business Activity/ Area of activity |
RTD Role in Project |
HES |
1 |
UK |
University, Dept of Materials |
Workpackage Leader/EU coordinator |
HES |
2 |
UK |
University, Dept of Materials |
Workpackage Leader |
REC |
3 |
France |
Research Institute, Materials |
Workpackage Leader |
REC |
4 |
Germany |
Research Institute, Materials |
Workpackage Leader |
HES |
5 |
Germany |
University, Dept of Materials |
Workpackage Leader |
HES |
6 |
US |
University, Institute of Ceramics |
Workpackage Leader/US Coordinator |
HES |
7 |
US |
University, Dept of Physics |
Workpackage Leader |
HES |
8 |
US |
University, Dept of Materials Ceramics |
Workpackage Leader |
HES |
9 |
US |
University, Dept of Materials |
Workpackage Leader |
HES |
10 |
US |
National Laboratory |
Workpackage Leader |
HES |
11 |
US |
University, Dept of Materials |
Workpackage Leader |
TABLE 4
AWAITING MANPOWER CHART DC TO DO
WORKPACKAGE MANPOWER BARCHART |
|||||||||||||||
|
Partners |
Duration/critical path |
*:see milestone list |
||||||||||||
|
ManMonths |
1st |
2nd |
3rd year |
|||||||||||
Workpackage Description |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
|
|
|
Workpackage 1: Title: Structural Characterisation
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Task 1.1 Title: Development of techniques for RDF analysis of small amorphous volumes
|
20 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Task 1.2 Title: Microanalysis of small volumes from delivered samples
|
28 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Task 1.3: Title: HREM of interfaces
|
36 |
|
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|
|
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|
|
|
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|
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|
|
Workpackage 2: Title: Ab initio Computations
|
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|
|
Task 2.1 Title: Development of continuous random network model for silicon
|
|
15 |
|
|
|
|
|
|
|
|
|
|
|
|
|
Task 2.2: Title: Incorporation of model into grand canonical simulation
|
|
12 |
|
|
|
|
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|
|
|
|
|
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|
|
Task 2.3: Title: Development of bond order potentials |
|
18 |
|
|
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|
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|
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|
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|
|
Task 2.4: Title: Refinement of predicted structures
|
|
20 |
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|
|
Task 2.5 Title: Comparison of predicted atomic and electron structure |
|
12 |
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|
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Workpackage 3: Title: Surface Analysis
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|
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Task 3.1 Title: Characterization of composition of thin films
|
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24 |
|
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|
|
Task 3.2 Title: Perform XPS, UPS and REELS experiments |
|
|
20 |
|
|
|
|
|
|
|
|
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|
|
Task 3.3: Title: Derive the surface electron energy loss function of thin films |
|
|
24 |
|
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|
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|
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Workpackage 4: Title: EELS and fine structure
|
|
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|
|
Task 4.1 Title: Measurement of EELS
|
|
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|
20 |
|
|
|
|
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|
|
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|
|
Task 4.2 Title: Calculation of fine structure |
|
|
|
18 |
|
|
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|
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|
|
Task 4.3 Title: Comparison of EELS and calculations |
|
|
|
12 |
|
|
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|
|
|
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|
|
Task 4.4 Title: Comparison to structural studies |
|
|
|
12 |
|
|
|
|
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|
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|
|
Task 4.5 Title: Correlation to mechanical properties |
|
|
|
10 |
|
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|
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|
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Workpackage 5: Title: Materials Growth and Testing
|
|
|
|
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|
|
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|
|
|
|
|
|
|
|
Task 5.1: Title: Processing of silicon nitride ceramics
|
|
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|
|
20 |
|
|
|
|
|
|
|
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|
|
Task 5.2: Title: Grain growth studies in polycrystalline ceramics
|
|
|
|
|
22 |
|
|
|
|
|
|
|
|
|
|
Task 5.3: Title: Determination of the macroscopic materials properties |
|
|
|
|
30 |
|
|
|
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|
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|
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|
|
Workpackage 6: Title: Phase Field Modelling of Stable Interfacial Films
|
|
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|
|
|
|
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|
|
|
|
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|
|
Task 6.1 Title: Development of coherent and useful thermodynamic model |
|
|
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|
|
25 |
|
|
|
|
|
|
|
|
|
Task 6.2 Title: Develop methods of coarse-graining structural data
|
|
|
|
|
|
25 |
|
|
|
|
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|
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|
|
Task 6.3 Title: Classify constrained film behaviour |
|
|
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|
|
27 |
|
|
|
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|
|
|
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|
|
|
|
|
|
|
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|
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|
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Workpackage 7: Title: Electronic Structure and Spectroscopic Properties
|
|
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|
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|
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|
|
Task 7.1 Title: Electronic structure/bonding and bulk properties of crystalline phases |
|
|
|
|
|
|
12 |
|
|
|
|
|
|
|
|
Task 7.2 Title: Optical properties and spectroscopic properties of crystals
|
|
|
|
|
|
|
18 |
|
|
|
|
|
|
|
|
Task 7.3 Title: Electronic structure and bonding of specific models of amorphous structure |
|
|
|
|
|
|
10 |
|
|
|
|
|
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|
|
Task 7.4 Title: Spectroscopic properties of interface models and amorphous structure
|
|
|
|
|
|
|
10 |
|
|
|
|
|
|
|
|
Task 7.5 Title: Comparison with interpretation of experimental data
|
|
|
|
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|
|
12 |
|
|
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|
|
Task 7.6 Title: Further development of computational methods in materials theory |
|
|
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|
|
10 |
|
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|
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|
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|
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|
|
|
|
|
|
|
|
|
|
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|
|
Workpackage 8: Title: Molecular Dynamics Simulations |
|
|
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|
|
Task 8.1 Title: MD Simulations of surface and interface structure of amorphous oxide films
|
|
|
|
|
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|
20 |
|
|
|
|
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|
|
Task 8.2 Title: Simulations of transport properties of ions in amorphous phase
|
|
|
|
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18 |
|
|
|
|
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|
|
Task 8.3 Title: Simulations of contact between dissimilar crystal orientations
|
|
|
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|
20 |
|
|
|
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|
|
Task 8.4 Title: Comparison of results with ab-initio calculations of local structures |
|
|
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|
17 |
|
|
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|
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|
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|
|
Workpackage 9: Title: Preparation and Characterization of Surface Films
|
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|
|
Task 9.1 Title: Prepare oxycarbide bicrystal and surface films in SiC
|
|
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|
|
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|
6 |
|
|
|
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|
|
Task 9.2 Title: Prepare Si-O-La and Si-O-N-La on Si single crystals
|
|
|
|
|
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|
10 |
|
|
|
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|
|
Task 9.3 Title: Use TEM/STEM and surface analytical to determine stability
|
|
|
|
|
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|
14 |
|
|
|
|
|
|
Task 9.4 Title: Measure capacitance, leakage current, and breakdown voltage of stable films |
|
|
|
|
|
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|
|
12 |
|
|
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|
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|
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|
|
Workpackage 10: Title: Interparticle forces and wetting
|
|
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|
|
Task 10.1 Title: Wetting behaviour
|
|
|
|
|
|
|
|
|
|
12 |
|
|
|
|
|
Task 10.2 Title: Grain boundary studies of SrTiO3 and Si3N4
|
|
|
|
|
|
|
|
|
|
12 |
|
|
|
|
|
|
|
|
|
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|
|
Workpackage 11: Title: Spatially Spatially Resolved Electronic
|
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|
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|
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|
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|
|
Task 11.1 Title: Determine optical properties and electronic structure
|
|
|
|
|
|
|
|
|
|
|
70 |
|
|
|
|
Task 11.2 Title: Determine optical properties |
|
|
|
|
|
|
|
|
|
|
74 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
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|
|
|
Workpackage 12: Title: Management and Exploitation |
|
|
|
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|
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|
|
Task 12.1 Title: Management of documentation
|
|
|
|
|
|
|
|
|
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|
6 |
|
|
|
Task 12.2 Title: Keep workpackage leaders informed
|
|
|
|
|
|
|
|
|
|
|
|
6 |
|
|
|
Task 12.3 Title: Ensure timelines are met
|
|
|
|
|
|
|
|
|
|
|
|
4 |
|
|
|
Task 12.4 Title: Arrange meetings |
|
|
|
|
|
|
|
|
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|
|
2 |
|
|
|
Task 12.5 Title: Seek exploitation opportunity |
|
|
|
|
|
|
|
|
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|
|
4 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Total MANMONTH |
84 |
77 |
68 |
72 |
72 |
77 |
72 |
75 |
42 |
24 |
144 |
22 |
|
|
|
In year 1 |
25 |
25 |
20 |
24 |
20 |
22 |
24 |
25 |
15 |
8 |
44 |
6 |
|
||
In year 2 |
26 |
27 |
23 |
24 |
26 |
26 |
24 |
25 |
14 |
8 |
50 |
6 |
6m 12m Mid-term 24m 30m Final |
||
In year 3 |
33 |
25 |
25 |
24 |
26 |
29 |
24 |
25 |
13 |
8 |
50 |
10 |
Reporting Periods |
||
TABLE 5
OVERVIEW OF MILESTONES AND DECISION CRITERIA
Milestone No |
Due date |
Brief description of Milestone Objectives |
Decision Criteria for assessment |
M1 |
M12 |
Grow Si-N ceramics |
Deliver material |
M2 |
M12 |
Grow Si-N ceramics |
Submitted paper |
M3 |
M12 |
Refinement of interatomic potentials via cf ab-initio data |
Submitted paper |
M4 |
M12 |
Completion of basic crystal phases |
Submitted paper |
M5 |
M12 |
Grow SiTiO3/Si3N4 |
Deliver material |
M6 |
M15 |
Hamaker constants for SrTiO3 |
Submitted paper |
M7 |
M15 |
Determination of surface electronic structures |
Submitted report |
M8 |
M18 |
Prepare Si-O-La films |
Conference presentations |
M9 |
M18 |
Technique for RDF of nanometer volumes |
Submitted paper |
M10 |
M18 |
Characterisation of amorphous films |
Submitted paper |
M11 |
M24 |
Completed calculations of interface and amorphous models |
Submitted paper |
M12 |
M24 |
Publication of phase field model that includes steric and osmotic effects |
Submission for publication |
M13 |
M24 |
Grand canonical simulations of Si-O-N films |
Submitted paper |
M14 |
M24 |
Development of BOP |
Submitted paper |
M15 |
M24 |
Grow-in and structures of defined systems |
Submitted paper |
M16 |
M24 |
Data of growth morphology and measure fracture toughness |
Distribution to partners |
M17 |
M24 |
Phase field model |
Submitted paper |
M18 |
M24 |
Develop consistent theory and publish |
Submitted paper |
M19 |
M24 |
Develop data extraction method and demonstrate use |
Submitted paper |
M20 |
M24 |
Simulation of surface structures of interface |
Submitted paper |
M21 |
M24 |
Measure electrical properties of Si-O-La films |
Submitted papers |
M22 |
M24 |
Wetting and adsorption behaviour |
Submitted paper |
M23 |
M24 |
Fine structural ELNES results |
Submitted paper |
M24 |
M24 |
Quantitative data on growth morphology |
Submitted paper |
M25 |
M24 |
Identify glass compositions |
Submitted paper |
M26 |
M24 |
Understanding ELNES fine structure from atomistic arrangements |
Submitted paper |
M27 |
M27 |
Hamaker constants for Si systems |
Submitted paper |
M28 |
M36 |
Completion of studies on crystalline and non-crystalline systems |
Submitted paper |
M29 |
M36 |
Application of theory using data derived from experiment and simulation |
Application of theory |
M30 |
M36 |
Characterisation of interface structures |
Submitted paper |
M31 |
M36 |
Grow-in and structures of defined systems |
Submitted paper |
M32 |
M36 |
Apply phase field model to experimental data and simulation |
Comparison reported |
M33 |
M36 |
Simulation of growth |
Submitted paper |
M34 |
M36 |
Electronic structure and chemical bonding of available thin Si-La-O amorphous films |
Submitted paper |
M35 |
M36 |
Stability and character of IGF films |
Submitted paper |
M36 |
M36 |
Correlation of microstructure and mechanical properties |
Submitted paper |
M37 |
M38 |
Comparison of amorphous film structures - experimental and modelling |
Submitted paper |
WORKPACKAGE DESCRIPTION
|
|||
Workpackage Title: STRUCTURAL CHARACTERISATION |
WP nr: 1 |
||
Starting date: month nr. 1 |
Duration: months 36 |
Total Effort |
|
Partners involved |
R & D Task/Activity of Partner |
Effort |
|
1 & ASSOCIATES |
ELECTRON DIFFRACTION AND MICROSCOPY |
84 |
|
|
|||
Objectives |
|||
1 |
To develop RDF techniques from nanometre-scale amorphous volumes. |
||
2 |
To characterise amorphous volumes using ED & HREM. |
||
3 4
|
Detailed examination of interface structure at near-atomic resolution. Comparison of model structures of films with experimental studies. |
||
Description of work / tasks |
|||
1 |
Development of techniques for RDF analysis of small amorphous volumes |
||
2 |
Microanalysis of small volumes from delivered samples. |
||
3 |
Investigation of interface structure at near atomic resolution.. |
||
4 5
|
Orientation relationships of adjacent crystals. Comparison of experimental data of amorphous phases with model structures. |
||
Deliverables |
|||
1 |
Technique for analysing nanometre-scale amorphous volumes |
||
2 |
Structural characterisation of interface materials. |
||
3
|
Characterisation of amorphous phases for comparison with model structures. |
||
Milestones and criteria |
|||
1 |
Technique for RDF of nanometre-scale volumes publication submitted 18 month. |
||
2 |
Characterisation of defined interface structures by HREM and RDF analysis publication submitted 36 month. |
||
3 4
|
Characterisation of amorphous films publication submitted 18 months. Comparison of amorphous film structures obtained experimentally and by modelling publication submitted 38 months. |
||
Interrelation with other workpackages |
|||
Experimental results closely compared with results from WP2 & WP4. |
|||
|
|
||
WORKPACKAGE DESCRIPTION
|
|||
Workpackage Title: AB INITIO COMPUTATIONS |
WP nr: 2 |
||
Starting date: month nr. 1 |
Duration: months 36 |
Total Effort |
|
Partners involved |
R & D Task/Activity of Partner |
Effort |
|
2& ASSOCIATES |
COMPUTATION & MODELLING |
77.4 |
|
|
|
|
|
Objectives |
|||
1 |
Random network model for silicon oxynitride films and incorporation into a grand economical simulation. Development of band order potential for the Si-N-O system. Refinement and testing against data.
|
||
|
|
||
Description of work / tasks
|
|||
1 |
The development of a continuous random network model for silicon oxynitride films in Si3N4 - SiO2.
|
||
2 |
The incorporation of that model into a grand canonical simulation at constant chemical potential, temperature and pressure of the structure and composition variations within the film at the atomic scale. |
||
3 |
The development of bond order potentials for the Si-N-O system, and their incorporation into the grand canonical simulation package. |
||
4 |
The refinement of the predicted structures of the glassy film with ab initio density functional simulations, and prediction of the local electronic structure of the film. |
||
5 |
Comparison of the predicted atomic and electronic structures with experiments in workpackages WP1 and WP4. |
||
|
|
||
Deliverables |
|||
1 |
CRN model for Si-N-O films in Si3N4-SiO2 |
||
2 |
BOP for Si-N-O |
||
3 |
Refined structural models compared with experiment. |
||
|
|
||
Milestones and criteria |
|||
1 |
First grand canonical simulations of silicon oxynitride films 24 month criteria paper submitted for publication. |
||
2 |
Development of bond order potentials for silicon oxynitride system completed 24 month criteria paper submitted for publication. |
||
|
|
||
Interrelation with other workpackages |
|||
This package will be closely
related to the experiments on structure and near edge structure to be
carried out in WP1 and WP4 respectively. The experiments will enable
the modelling to be tested, and the modelling will enable the
experimental results to be interpreted in detail. |
|||
WORKPACKAGE DESCRIPTION
|
||
Workpackage Title: SURFACE ANALYSIS AND SPECTROSCOPIC PROPERTIES |
WP nr: 3 |
|
Starting date: month nr. 1 |
Duration: months 36 |
Total Effort |
Partners involved |
R & D Task/Activity of Partner |
Effort |
3 & ASSOCIATES |
ANALYSIS AND GROWTH |
68 |
|
|
|
|
|
|
|
|
|
|
|
|
|
||
Objectives 1. Determine surface electronic structure of thin films, by using REELS, XPS and UPS. 2. Characterize the chemical bonding in the very thin amorphous films (e.g. Si-La-O), compared with pure SiO2 and bulk glass phases.
|
||
Description of work / tasks1. Characterization of the composition of thin films grown in WP5 and WP9 (Si-La-O, SrTiO3) 2. Perform XPS, UPS and REELS experiments on amorphous thin films grown in WP9 3. Derive the surface electron energy loss function of these thin films
|
||
Deliverables1. Compositional characterization of surface films 2. REELS data on surface films
|
||
Milestones and criteria1. Determination of the surface electronic structure of SrTiO3 on available samples (XPS, UPS, REELS) month 15 2. Electronic structure and chemical bonding of available thin Si-La-O amorphous films month 36.
|
||
Interrelation with other workpackages Strong interactions with WP9, who will prepare the thin films analyzed in this workpackage, with WP11, for the REELS data analysis and derivation of surface optical properties, compared to VUV optical measurements and also EELS data obtained in WP4. Interaction also with WP7, for comparison between theoretical and experimental electronic structure of th thin films.
|
||
WORKPACKAGE DESCRIPTION
|
||
Workpackage Title: ELECTRON ENERGY LOSS SPECTROSCOPY AND FINE STRUCTURES |
WP nr: 4 |
|
Starting date: month nr. 1 |
Duration: months 36 |
Total Effort |
Partners involved |
R & D Task/Activity of Partner |
Effort |
4& ASSOCIATES |
EELS AND CALCULATIONS |
72 |
|
|
|
|
|
|
|
|
|
|
|
|
|
||
ObjectivesMeasurement of Electron energy loss spectra with variable spatial and high-energy resolution for all elements present in the material. Measurement of fine structure of electron energy loss spectra, high-resolution TEM of interfacial layers. Calculation of fine structures by ab-initio calculations. Testing of data.
|
||
Description of work / tasks
1.
Measurement
of different electron energy loss spectra in a special transmission
electron microscope with in-column filter (SESAM:
sub-eVolt-Sub-Ångström-Microscope).
2.
Calculation
of fine structure for different structures by quantum mechanical
calculations.
3.
Comparison
between calculated and simulated results.
4.
Comparison
to structural studies. 5. Correlation to mechanical properties.
|
||
Deliverables1. Information on structure and composition of Si-N-O films in different Si3N4 ceramics. 2. Information on interaction between crystalline structures and amorphous films.
|
||
Milestones and criteria1. Understanding of fine structure (ELNES) from atomistic arrangements: 24 months.
2.
Correlation
between microstructure and mechanical properties: 36 months |
||
Interrelation with other workpackages
Close interaction
with workpackage WP1, WP4 and WP5 |
||
WORKPACKAGE DESCRIPTION
|
||
Workpackage Title: MATERIALS GROWTH AND TESTING |
WP nr: 5 |
|
Starting date: month nr.1 |
Duration: months 36 |
Total Effort |
Partners involved |
R & D Task/Activity of Partner |
Effort |
5 & ASSOCIATES |
MATERIALS GROWTH AND TESTING |
72 |
|
|
|
|
|
|
Objectives1. To process Si-N ceramics as in (a) below. 2. Analyse growth kinetics and influence of film composition on growth morphology. 3. Determine macroscopic properties as in (c) below.
|
||
Description of work / tasks1. Processing of silicon nitride ceramics with small quantities of different oxide additives and silica by using sinter-HIPing. The additives will be selected in terms of electronic structure and ionic size.
2. Grain growth studies in polycrystalline ceramics and oxynitride
glasses to analyse the growth kinetics and the influence of the
intergranular film composition on the growth morphology.
|
||
Deliverables
1. Samples with different intergranular films for the electron
microscopy groups. |
||
Milestones and criteria
(a)
1. (after 12
month): 5 types of dense silicon nitride ceramics containing different
intergranular film compositions; Identify alumina-free oxynitride glass
compositions to perform the model experiments; submission of a paper.
|
||
Interrelation with other workpackages
Strong interactions with WP1
and WP3 in characterization of structure and composition of the
intergranular films; WP2 will use our experimental grain growth data
for modelling ; WP7 will deliver an explanation for the specific
behaviour of the additive systems due to the difference in electronic
structure; WP11 will use our materials to perform spatially resolved
measurement of the electronic structure and dispersion forces. |
||
WORKPACKAGE DESCRIPTION
|
|||
Workpackage Title: PHASE FIELD MODELLING OF STABLE INTERFACIAL FILMS |
WP nr: 6 |
||
Starting date: month nr.1 |
Duration: 36 months |
Total Effort |
|
Partners involved |
R & D Task/Activity of Partner |
Effort |
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POSTDOC, STUDENT, COLLEAGUES |
MODELLING, COMPUTATION, DATA EXTRACTION |
77 |
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Objectives1. Development of a continuum thermodynamic framework that includes steric, composition gradient, and atomic structure and allows quantitative and verifiable predictions to be made with a relatively small set of engineering parameters.
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Description of work / tasks1. Development of a coherent and useful thermodynamic model for confined amorphous thin films. 2. To develop methods of coarse-graining structural data from molecular simulation and experiment and reduce large data sets into quantifiable theories. 3. To classify constrained film behavior with a small set of measurable parameters.
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Deliverables1. Publication of a theory and its application to stabilized amorphous films in term of interface structure and composition. 2. Demonstrated and articulated technique of coarse-graining and data extraction from simulation and experiment. |
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Milestones and criteria1. Development of consistent theory and associated paper submitted for publication: 24 month criterion. 2. Development of data extraction method and demonstration of its applicability, submission of paper, 24 month criterion.
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Interrelation with other workpackages 1. This project will utilize data and modelling methods from WP1 to derive composition-dependent steric terms that will be included in a continuum gradient energy term. 2. Structures predicted and reported by WP2 and WP7 as input for coarse-graining data extraction. 3. Data obtained by WP3 will be compared against model results of equilibrium composition profiles. 4. Simulations by WP8 will be used to derive energies and decay lengths for structural energies. 5. WP10 will provide characterization experiments and data for model verification. WP10 will also assist in model development.
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WORKPACKAGE DESCRIPTION
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Workpackage Title: ELECTRONIC STRUCTURE AND SPECTROSCOPIC PROPERTIES |
WP nr:7 |
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Starting date: month nr.1 |
Duration: months 36 |
Total Effort |
Partners involved |
R & D Task/Activity of Partner |
Effort |
1 & ASSOCIATES |
AB-INITIO ELECTRONIC STRUCTURE AND PROPERTIES CALCULATIONS |
72 |
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Objectives1. Electronic structure calculation and materials properties evaluation based on ab-initio technique. 2. Detailed studies on crystalline, amorphous and interface model structures. 3. Development of predictive methods for materials characterization.
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Description of work / tasks1. Electronic structure/bonding and bulk properties of crystalline phases of Si3N4, SiC, Si-O-N, Si-O-C, Si-Al-O-N, AlN, GaN, ZnO, SiO2, Mg2SiO4, MgSiO3, MgAl2O4, Al2O3, Y3Al5O12, Y2O3,Y2SiO5, Fe2O3, Fe3O4, Y3Fe5O12, Bi2O3, SrTiO3 and other related phases. 2. Optical properties and spectroscopic properties (ELNES/XANES, EELS, XES) of the above crystals. 3. Electronic structure and bonding of specific models of amorphous structure and interface models developed by other partners. 4. Spectroscopic properties of the interface models and amorphous structures using ab-initio method. 5. Comparison with and interpretation of experimental data based on calculated electronic properties. 6. Further development of computational methods in materials theory.
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Deliverables1. Publications of the work described above. 2. Provision of useful parameters from ab-initio calculations for MD simulation and continuum-scale modelling. 3. Provision of theoretical database of band structures, ELNES spectra (fingerprints), optical properties etc. for materials characterization and experimental interpretations. 4. Development of new and robust methods in computational materials theory
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Milestones and criteria1. Completion of the targeted studies on basic crystal phases. (Submission and publications in high-impact journals, 12 months). 2. Substantial progress and completion of calculations on some of the interface and amorphous models. (Publications in high-impact journals, 24 months). 3. Completion of additional studies on both crystalline and non-crystalline systems. (Publications in high-impact journals, 36 months).
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Interrelation with other workpackages This package is closely related to all other packages in both theory/computation (WP2,WP6,WP8,WP11) and experiments (WP1,WP3, WP4,WP5,WP9,WP10).
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WORKPACKAGE DESCRIPTION
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Workpackage Title: MOLECULAR DYNAMICS SIMULATIONS |
WP 8: |
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Starting date: month nr.1 |
Duration: months 36 |
Total Effort |
Partners involved |
R & D Task/Activity of Partner |
Effort |
2 (1PD, 1 grad. student) |
COMPUTATIONAL MODELLING |
75 |
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Objectives1. Simulations of atomistic structure of the intergranular glassy phase in contact with nitride and oxide surfaces and transport of ions within thin film glassy phase and at interface. Refinement of potentials via collaborations and comparisons to experiment.
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Description of work / tasks1. MD simulations of the surface and interface structure of the amorphous oxide films on Si3N4, SiC, and SrTiO3 and the effect of additives in the amorphous films on structure. 2. Simulations of transport properties of ions in the amorphous phase as a function of composition. 3. Simulations of contact between dissimilar crystal orientations in contact with the same intergranular film. 4. Comparison of all results with ab-initio calculations of local structures and available experimental data for refinement of the potentials.
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Deliverables1. Simulations relating to structure of intergranular film/crystal interfaces and evaluation of transport properties in glassy film . 2. Behavior of dissimilar surfaces reporting of
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Milestones and criteria1. Refinement of interatomic potentials via comparison to ab-initio data (12 mnths, publication). 2. Simulation of surface structures of silicon nitride and oxynitride and interface with glassy phase (24 mnths, publication). 3. Simulation of growth (36 months, publication).
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Interrelation with other workpackages This is related to WP 2, 7 and 9 for structures, ELNES calculations, and experimental data.
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WORKPACKAGE DESCRIPTION
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Workpackage Title: PREPARATION AND CHARACTERIZATION OF SURFACE FILMS |
WP nr: 9 |
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Starting date: month nr. 1 |
Duration: 36 months |
Total Effort |
Partners involved |
R & D Task/Activity of Partner |
Effort |
9 & ASSOCIATES |
MATERIALS SYNTHESIS AND CHARACTERIZATION |
42 |
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Objectives1. Thin surface films of oxide, oxycarbide, and oxynitride compositions will be prepared on SiC and Si single crystals, and heat treated to determine the temperature and composition dependence of film thickness. 2. Film morphology, composition, and structure will be characterized. Electrical properties relevant to applications as gate or DRAM oxides will be measured.
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Description of work / tasks1. Prepare oxycarbide bicrystal and surface films in SiC 2. Prepare Si-O-La and Si-O-N-La on Si single crystals 3. Use TEM/STEM and surface analytical methods to determine stability conditions for surface films 4. Measure capacitance, leakage current, and breakdown voltage of stable films on Si and SiC
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Deliverables1. Publication of experimental results in 1-4. 2. Supply samples to other members of group for characterization
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Milestones and criteria1. Prepare Si-O-La amorphous or partially ordered films on Si 18 month criteria - present results at conferences. 2. Measure electrical properties of Si-O-La films on Si 24 month criteria paper submitted for publication.
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Interrelation with other workpackages Materials produced in this workpackage will be characterized in WP1, WP3 and WP10, and modelled in WP2 and WP8.
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WORKPACKAGE DESCRIPTION
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Workpackage Title: INTERPARTICLE FORCES AND WETTING |
WP nr: 10 |
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Starting date: month nr. 1 |
Duration: months 36 |
Total Effort |
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Partners involved |
R & D Task/Activity of Partner |
Effort |
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10 & ASSOCIATES |
MODELLING OF INTERPARTICLE WETTING & PREWETTING |
6 |
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POST DOCS |
EXPERIMENTAL EVALUATION OF WETTING AND |
18 |
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COLLOIDAL BEHAVIOR |
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Objectives1. Develop unified description of intergranular films in terms of adsorption theory, wetting and prewetting behavior and colloidal approaches to interparticle interactions. 2. Seek correlations of thermodynamical and materials properties with interfacial film behavior and wetting transitions as well as with interparticle forces. 3. Verify behavior via experiments involving grain boundary penetration and high temperature colloidal behavior of grains in silicate or titanate rich liquids.
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Description of work / tasks1. In collaboration with WP6 will seek descriptions and models that anticipate prewetting and wetting behavior of silicate or titanate rich intergranular and surficial films. These will incorporate dispersion forces determined with WP11 and other shorter range interactions. Correlation will be made with stability or wetting of (La,Y)-Si-O-N films on Si observed in WP9. 2. Experiments will involve grain boundary penetration of SrTiO3 polycrystals and bicrystals via liquids with various additives, and assessment of colloidal behavior of particles in TiO2 rich eutectic liquid. Similar experiments will be done with Si3N4. Samples will be provided for TEM assessment of boundary character. |
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Deliverables1. Samples of SrTiO3 or Si3N4 for TEM examination 12 months 2. Paper on wetting and adsorption behavior 24 months 3. Paper on stability, character of IGF films in Si3N4 36 months
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Milestones and criteria1. Evaluation of interganular films and wetting transitions for SrTiO3 or Si3N4 based on penetration or colloidal experiments and TEM 18 months 2. Submission of papers - above |
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Interrelation with other workpackages Collaborate on modelling with WP6 and relation to experiments with WP5 and WP9. Provide samples for TEM to WP4 and WP1.
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WORKPACKAGE DESCRIPTION |
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Workpackage Title: SPATIALLY RESOLVED ELECTRONIC STRUCTURE |
WP nr:11 |
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Starting date: month nr.1 |
Duration: months 36 |
Total Effort |
Partners involved |
R & D Task/Activity of Partner |
Effort |
11 & ASSOCIATES |
COMPUTATIONAL STUDIES |
144 |
Objectives1. Determine electronic structure of the bulk silicon based systems Si, SiC an Si3N4 using VUV spectroscopy and Ellipsometry, using currently available samples. 2. Determine electronic structure of the bulk strontium titanate using VUV spectroscopy and Ellipsometry using currently available samples. 3. Determine electronic structure of the bulk silicon based systems Si, SiC and Si3N4 using VEELS microscopy, using currently available samples. 4. Determine electronic structure of the bulk strontium titanate using VEELS microscopy using currently available samples. 5. Survey current literature data on optical properties and electronic structure and where necessary update results of reference materials to permit accurate calculations of full spectral Hamaker constants. 6. Determine spatially resolved electronic structure and optical properties for intregranular and surficial films in the silicon based materials system for the determination of full spectral Hamaker constants for the London dispersion forces. 7. Determine spatially resolved electronic structure and optical properties for intregranular and surficial films in the strontium titanate based materials system for the calculation of full spectral Hamaker constants for the London dispersion forces. 8. Develop quantitative analysis of surface reflection valence electron energy loss spectroscopy of silicon or strontium titanate bulk system.
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Description of work / tasks1. Determine the optical properties and electronic structure of bulk samples from the silicon system and the strontium titanate system, 2. Determine the optical properties and electronic structure of the intergranular and surficial materials, as bulk samples using spatially resolved probes of the interfacial or surficial samples.
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Deliverables1. Publication of bulk optical properties and electronic structure of the reference silicon and of strontium titanate systems. Objectives a,b,c, or d 2. Publication of the optical properties and electronic structure of an intergranular films in the silicon nitride or strontium titanate system. Objective f or g
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Milestones and criteriaMilestone 1. Hamaker constants for silicon systems, month 27, inclusion in submitted paper Milestone 2. Hamaker constants for strontium titanate systems, month 15, inclusion in submitted manuscript.
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Interrelation with other workpackages Interactions are with the sample preparation packages from WP3 and WP5 Interactions are with the characterization packages of WP2, WP3 and WP4 Interactions of the results with results of band structure theorists from WP2 and WP8 Interactions with the final system properties. |
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WORKPACKAGE DESCRIPTION
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Workpackage Title: MANAGEMENT AND EXPLOITATION |
WP nr: 12 |
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Starting date: month nr. 1 |
Duration: months 36 |
Total Effort |
Partners involved |
R & D Task/Activity of Partner |
Effort |
1 & SECRETARY |
MANAGEMENT |
10 |
EXPLOITATION MANAGER |
SEEK EXPLOITATION |
12 |
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Objectives1. To manage the EU partnership and to coordinate with US coordinator.
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Description of work / tasks1. Management of documentation. 2. Keep workpackage leaders informed. 3. Ensure timelines are met. 4. Arrange meetings. 5. Seek exploitation opportunities.
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Deliverables1. Successful outcome of programme. 2. Reports to EU.
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Milestones and criteria6 monthly reporting successful.
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Interrelation with other workpackages. Coordination of WP1-5 and with US Coordinator.
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