prof. dr hab. inż. Paweł Dłużewski

Zakład Informatyki i Nauk Obliczeniowych (ZIiNO)
Pracownia Metod Komputerowych Inżynierii Materiałowej (PMKIM)
stanowisko: profesor zwyczajny
telefon bezpośredni: (+48) 22 827 46 92
telefon: (+48) 22 826 12 81 wew.: 184
pokój: 424
e-mail: pdluzew
strona www: http://bluebox.ippt.pan.pl/~pdluzew/

Doktorat
1985Zastosowanie teorii poślizgów do opisu procesów deformacji niesprężystych 
promotor -- prof. dr hab. inż. Piotr Perzyna, IPPT PAN
422 
Habilitacja
1997Kontynualna teoria dyslokacji jako teoria konstytutywnego modelowania skończonych, sprężysto-plastycznych deformacji 
Profesura
2009-12-30Nadanie tytułu naukowego profesora
Promotor prac doktorskich
1.2006-06-29Jurczak Grzegorz  Anizotropia sprężysta kryształów. Analiza i modelowanie numeryczne metodą elementów skończonych.595
 
2.2006-01-26Traczykowski Piotr  Wykorzystanie statyki molekularnej do modelowania procesów deformacji kryształów półprzewodnikowych590
 
3.2003-03-06Maciejewski Grzegorz  Zastosowanie metody elementów skończonych do wyznaczania rozkładów naprężeń residualnych w heterostrukturach568
 

Ostatnie publikacje
1.Domagała J.Z., Morelhão S.L., Sarzyński M., Maździarz M., Dłużewski P., Leszczyński M., Hybrid reciprocal lattice: application to layer stress determination in GaAlN/GaN(0001) systems with patterned substrates, JOURNAL OF APPLIED CRYSTALLOGRAPHY, ISSN: 1600-5767, DOI: 10.1107/S1600576716004441, Vol.49, No.3, pp.798-805, 2016
Domagała J.Z., Morelhão S.L., Sarzyński M., Maździarz M., Dłużewski P., Leszczyński M., Hybrid reciprocal lattice: application to layer stress determination in GaAlN/GaN(0001) systems with patterned substrates, JOURNAL OF APPLIED CRYSTALLOGRAPHY, ISSN: 1600-5767, DOI: 10.1107/S1600576716004441, Vol.49, No.3, pp.798-805, 2016

Abstract:
Epitaxy of semiconductors is a process of tremendous importance in applied science and in the optoelectronics industry. The control of defects introduced during epitaxial growth is a key point in manufacturing devices of high efficiency and durability. In this work, it is demonstrated how useful hybrid reflections are for the study of epitaxial structures with anisotropic strain gradients due to patterned substrates. High accuracy in detecting and distinguishing elastic and plastic relaxations is one of the greatest advantages of measuring this type of reflection, as well as the fact that the method can be exploited in a symmetric reflection geometry on a commercial high-resolution diffractometer.

Keywords:
optoelectronics, Group III-nitride semiconductors, epitaxial growth, X-ray multiple diffraction, interface defects

40p.
2.Jurczak G., Dłużewski P., Finite element modelling of nonlinear piezoelectricity in wurtzite GaN/AlN quantum dots, COMPUTATIONAL MATERIALS SCIENCE, ISSN: 0927-0256, DOI: 10.1016/j.commatsci.2015.09.024, Vol.111, pp.197-202, 2016
Jurczak G., Dłużewski P., Finite element modelling of nonlinear piezoelectricity in wurtzite GaN/AlN quantum dots, COMPUTATIONAL MATERIALS SCIENCE, ISSN: 0927-0256, DOI: 10.1016/j.commatsci.2015.09.024, Vol.111, pp.197-202, 2016

Abstract:
In this paper we evaluate the effect of higher order elastic and piezoelectric coefficients on elastic and electric fields in III-nitride wurtzite crystals. To this end, finite element calculations of GaN/AlN QDs of different types are presented and compared. We show that the nonlinear elastic and piezoelectric effects modify the elastic strain field, electrostatic potential, and the build-in electric field in the QDs. These higher order effects lead to corrections of the peak values of the strain field and the electrostatic potential over 8% above the linear model. An even more significant effect, exceeding 13%, is observed for the magnitude of the electric field. Our calculations clearly show that the impact of the nonlinear correction strongly depends on the application, i.e. on the morphology and crystallographic orientation of the quantum dot. It turns out that nonlinear effects play an important role in the semipolar (View the MathML source112¯2) and nonpolar (View the MathML source112¯0) QDs. Because of the theoretical nature of physical parameters describing nonlinear material (obtained by DFT calculations) further studies and experimental verification of the nonlinear effects in nitride structures are necessary.

Keywords:
Piezoelectricity, Heterostructure, Nonlinearity, Quantum dot

30p.
3.Young T.D., Jurczak G., Lotsari A., Dimitrakopulos G.P., Komninou Ph., Dłużewski P., A study of the piezoelectric properties of semipolar 11(2)over-bar2 GaN/AlN quantum dots, PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, ISSN: 0370-1972, DOI: 10.1002/pssb.201552156, Vol.252, No.10, pp.2296-2303, 2015
Young T.D., Jurczak G., Lotsari A., Dimitrakopulos G.P., Komninou Ph., Dłużewski P., A study of the piezoelectric properties of semipolar 11(2)over-bar2 GaN/AlN quantum dots, PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, ISSN: 0370-1972, DOI: 10.1002/pssb.201552156, Vol.252, No.10, pp.2296-2303, 2015

Abstract:
GaN quantum dots grown in (inline image)’orientated AlN are studied. The inline image-nucleated quantum dots exhibit rectangular- or trapezoid-based truncated pyramidal morphology. Another quantum dot type orientated on inline image is reported. Based on high-resolution transmission microscopy and crystal symmetry, the geometry of inline image-orientated quantum dots is proposed. A piezoelectric model is used within a finite element method to determine and compare the strain-state and electrostatic potential associated with the quantum dot morphology and an estimation of the band-edge energy is made. We report on some novel properties of the inline image-orientated quantum dot, including mixed strain-states and strain-state bowing.

Keywords:
III–V semiconductors, AlN, GaN, nanostructures, piezoelectric properties, quantum dots

20p.
4.Cholewiński J., Maździarz M., Jurczak G., Dłużewski P., Dislocation core reconstruction based on finite deformation approach and its application to 4H-SiC crystal, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.2014010679, Vol.12, No.5, pp.411-421, 2014
Cholewiński J., Maździarz M., Jurczak G., Dłużewski P., Dislocation core reconstruction based on finite deformation approach and its application to 4H-SiC crystal, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.2014010679, Vol.12, No.5, pp.411-421, 2014

Abstract:
A proper reconstruction of discrete crystal structure with defects is an important problem in dislocation theory. Currently, procedures for dislocation core reconstruction presented in the literature usually neglect configuration changes. The present paper discusses a new approach, which uses an iterative algorithm to determine an atomistic configuration of the dislocation core. The mathematical background is based on finite deformation theory, in which an iterative algorithm searches for the new atomic configuration corresponding to the actual atomic configuration of the deformed crystal. Its application to the reconstruction of 4H-SiC crystal affected by the system of four threading dislocations is presented as an example. Molecular statics calculations suggest a lower potential energy, as well as dislocation core energy, per-atom energy, and per-atom stresses for the structure reconstructed by use of the iterative algorithm against the classical solution based on the Love's equations.

Keywords:
dislocation, dislocation core energy, finite deformation, molecular statics

25p.
5.Dłużewski P., Cholewiński J., Continuum and atomistic modelling of crystal defects, Annual Report - Polish Academy of Sciences, ISSN: 1640-3754, pp.80-82, 2013
6.Dimitrakopulos G.P., Kalesaki E., Kioseoglou J., Kehagias T., Lotsari A., Lahourcade L., Monroy E., Häusler I., Kirmse H., Neumann W., Jurczak G., Young T.D., Dłużewski P., Komninou Ph., Karakostas T., Morphology and strain of self-assembled semi-polar GaN quantum dots in (1112) AlN, JOURNAL OF APPLIED PHYSICS, ISSN: 0021-8979, Vol.108, pp.104304-1-9, 2010
Dimitrakopulos G.P., Kalesaki E., Kioseoglou J., Kehagias T., Lotsari A., Lahourcade L., Monroy E., Häusler I., Kirmse H., Neumann W., Jurczak G., Young T.D., Dłużewski P., Komninou Ph., Karakostas T., Morphology and strain of self-assembled semi-polar GaN quantum dots in (1112) AlN, JOURNAL OF APPLIED PHYSICS, ISSN: 0021-8979, Vol.108, pp.104304-1-9, 2010

Abstract:
GaN quantum dots (QDs) grown in semipolar (11-22) AlN by plasma-assisted molecular-beam epitaxy were studied by transmission electron microscopy (TEM) and scanning transmission electron microscopy techniques. The embedded (11-2)-grown QDs exhibited pyramidal or truncated-pyramidal morphology consistent with the symmetry of the nucleating plane, and were delimited by nonpolar and semipolar nanofacets. It was also found that, in addition to the (11-22) surface, QDs nucleated at depressions comprising {10-11} facets. This was justified by ab initio density functional theory calculations showing that such GaN/AlN facets are of lower energy compared to (11-22). Based on quantitative high-resolution TEM strain measurements, the three-dimensional QD strain state was analyzed using finite-element simulations. The internal electrostatic field was then estimated, showing small potential drop along the growth direction, and limited localization at most QD interfaces.

Keywords:
Quantum dots, Transmission electron microscopy, III-V semiconductors, High resolution transmission electron microscopy, Epitaxy

32p.
7.Dłużewski P., Young T.D., Dimitrakopulos G., Komninou Ph., Continuum and atomistic modelling of the mixed straight dislocation, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.v8.i3.80 , Vol.8, pp.331-342, 2010
Dłużewski P., Young T.D., Dimitrakopulos G., Komninou Ph., Continuum and atomistic modelling of the mixed straight dislocation, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.v8.i3.80 , Vol.8, pp.331-342, 2010

Abstract:
A continuum and atomistic approach to the modeling of dislocations observed by high-resolution transmission electron microscopy (HRTEM) is discussed in terms of the continuum theory of dislocations. The atomistic models are obtained by means of the use of a mathematical formula for discrete dislocations. A new analytical solution for a continuously distributed dislocation core is presented. This solution is employed in the finite element modeling of residual stresses induced by the net of dislocations visible on an HRTEM image of GaN structure. This paper terminates with some comments on the atomistic/finite-element modeling of dislocation fields. Because of some confusion concerning notations used in the literature, the mathematical foundations of the continuum theory of dislocations are revisited.

Keywords:
dislocations, field theory, atomistic models, finite element method, high-resolution transmission electron microscopy

27p.
8.Maździarz M., Young T.D., Dłużewski P., Wejrzanowski T., Kurzydłowski K.J., Computer modelling of nanoindentation in the limits of a coupled molecular-statics and elastic scheme, JOURNAL OF COMPUTATIONAL AND THEORETICAL NANOSCIENCE, ISSN: 1546-1955, DOI: 10.1166/jctn.2010.1469, Vol.7, pp.1-10, 2010
Maździarz M., Young T.D., Dłużewski P., Wejrzanowski T., Kurzydłowski K.J., Computer modelling of nanoindentation in the limits of a coupled molecular-statics and elastic scheme, JOURNAL OF COMPUTATIONAL AND THEORETICAL NANOSCIENCE, ISSN: 1546-1955, DOI: 10.1166/jctn.2010.1469, Vol.7, pp.1-10, 2010

Abstract:
Our numerical approach to modeling elastic-plastic deformation comes back to the idea of the time-independent plasticity developed here at the molecular-statics level. We use a constitutive atomic model based on the second-moment approximation of the tight-binding potential coupled to a linear theory of elasticity solved simultaneously within the finite element method. Our model is applied to the nanoindentation problem for copper in which the indenter is represented by the equations of a sphere. For convenience the time-dependency of the nanoindentation problem is reduced to a quasi-static adiabatic scheme. A recurring theme in this paper is to determine the response of the proposed model for two differing systems: mono and polycrystalline copper. This paper discusses the force-depth response in terms of atomic bond-lengths, elastic-plastic deformations, and the instantaneous stiffness of the material. We report on an increased instantaneous stiffness of polycrystalline copper compared to that of its monocrystalline counterpart. From both a distinct and a comparative analysis of both systems, based on the relaxed positions of the atoms in the structure during the simulation, we deduce that plastic deformations at grain-boundaries are responsible for this change in the overall instantaneous stiffness of the material.

Keywords:
linear elasticity, material science, molecular statics, nanoindentation, quasicontinuum methods

27p.
9.Dłużewski P., Maździarz M., Traczykowski P., Jurczak G., Niihara K., Nowak R., Kurzydłowski K., A hybrid atomistic-continuum finite element modelling of nanoindentation and experimental verification for copper crystal, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, Vol.15, pp.37-44, 2008
Dłużewski P., Maździarz M., Traczykowski P., Jurczak G., Niihara K., Nowak R., Kurzydłowski K., A hybrid atomistic-continuum finite element modelling of nanoindentation and experimental verification for copper crystal, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, Vol.15, pp.37-44, 2008

Abstract:
Problem of locally disordered atomic structure is solved by using a hybrid formulation in which nonlinear elastic finite elements are linked with discrete atomic interaction elements. The continuum approach uses nonlinear hyperelasticity based upon the generalized strain while the atomistic approach employs the Tight-Binding Second-Moment Approximation potential to create new type of elements. The molecular interactions yielding from constitutive models of TB-SMA were turned into interactions between nodes to solve a boundary value problem by means of finite element solver.
In this paper we present a novel way of modelling materials behaviour where both discrete (molecular dynamics) and continuum (nonlinear finite element) methods are used. As an example, the nanoindentation of a copper sample is modelled numerically by applying a hybrid formulation. Here, the central area of the sample subject to a nanoindentation operation is discretised by an atomic net where the remaining area of the sample far from indenters tip is discretised by the use of a nonlinear finite element mesh.

Keywords:
Nanostructure, Nanoindentation, Molecular statics, Finite element modelling

10.Young T.D., Kioseoglou J., Dimitrakopulos G.P., Dłużewski P., Komninou Ph., 3D modelling of misfit networks in the interface region of heterostructures, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, DOI: 10.1088/0022-3727/40/13/027, Vol.40, pp.4084-4091, 2007
Young T.D., Kioseoglou J., Dimitrakopulos G.P., Dłużewski P., Komninou Ph., 3D modelling of misfit networks in the interface region of heterostructures, JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN: 0022-3727, DOI: 10.1088/0022-3727/40/13/027, Vol.40, pp.4084-4091, 2007

Abstract:
We present a methodology for the stress–strain analysis of a film/substrate interface by combining crystallographic and continuum modelling. Starting from measurements of lattice parameters available from experimental observations, the heterostructure is recast initially in the form of a crystallographic model and finally as a continuum elastic model. The derived method is capable of handling dense arrays of misfit dislocations as well as large areas of the interface between two crystal structures. As an application we consider the misfit dislocation network in the GaN/Al2O3 interface region through determination of strain relaxation and associated residual stresses. Our calculated results are referred back to and found to be in good agreement with the experimental observations of misfit dislocation arrays obtained from high resolution transmission electron microscopy.

11.Kret S., Dłużewski P., Szczepańska A., Żak M., Czernecki R., Kryśko M., Leszczyński M., Maciejewski G., Homogenous indium distribution in InGaN/GaN laser active structure grown by LP-MOCVD on bulk GaN crystal revealed by transmission electron microscopy and X-ray diffraction, NANOTECHNOLOGY, ISSN: 0957-4484, DOI: 10.1088/0957-4484/18/46/465707, Vol.18, No.46, pp.465707-0, 2007
Kret S., Dłużewski P., Szczepańska A., Żak M., Czernecki R., Kryśko M., Leszczyński M., Maciejewski G., Homogenous indium distribution in InGaN/GaN laser active structure grown by LP-MOCVD on bulk GaN crystal revealed by transmission electron microscopy and X-ray diffraction, NANOTECHNOLOGY, ISSN: 0957-4484, DOI: 10.1088/0957-4484/18/46/465707, Vol.18, No.46, pp.465707-0, 2007

Abstract:
We present transmission electron microscopy (TEM) and x-ray quantitative studies of the indium distribution in InxGa1−xN/GaN multiple quantum wells (MQWs) with x = 0.1 and 0.18. The quantum wells were grown by low-pressure metalorganic chemical vapour deposition (LP-MOCVD) on a bulk, dislocation-free, mono-crystalline GaN substrate. By using the quantitative TEM methodology the absolute indium concentration was determined from the 0002 lattice fringe images by the strain measurement coupled with finite element (FE) simulations of surface relaxation of the TEM sample. In the x-ray diffraction (XRD) investigation, a new simulation program was applied to monitor the indium content and lateral composition gradients. We found a very high quality of the multiple quantum wells with lateral indium fluctuations no higher than ΔxL = 0.025. The individual wells have very similar indium concentration and widths over the whole multiple quantum well (MQW) stack. We also show that the formation of 'false clusters' is not a limiting factor in indium distribution measurements. We interpreted the 'false clusters' as small In-rich islands formed on a sample surface during electron-beam exposure.

12.Dłużewski P., Nonlinear field theory of stress induced interdiffusion and mass transport, DEFECT AND DIFFUSION FORUM, ISSN: 1662-9507, DOI: 10.4028/www.scientific.net/DDF.264.63, Vol.264, pp.63-70, 2007
Dłużewski P., Nonlinear field theory of stress induced interdiffusion and mass transport, DEFECT AND DIFFUSION FORUM, ISSN: 1662-9507, DOI: 10.4028/www.scientific.net/DDF.264.63, Vol.264, pp.63-70, 2007

Abstract:
Constitutive equations for interdiffusion and mass transport induced by the stress gradient in crystal lattice is presented in terms of continuum thermodynamics. Only the standard balance laws are analysed for the mass, momentum, moment of momentum, energy and entropy. In consequence the driving forces for interdiffusion of chemical constituents are determined. The forces depend not only on the stress gradient but also on the gradients of chemical components and temperature. The driving forces are used next in constitutive modelling of interdiffusion and mass transport in crystal lattice.

Keywords:
Chemical Strain, Driving Force, Interdiffusion, Kirkendall Effect, Mass Transport

13.Teisseyre H., Suski T., Łepkowski S.P., Perlin P., Jurczak G., Dłużewski P., Daudin B., Grandjean N., Strong electric field and nonuniformity effects in GaN/AlN quantum dots revealed by high pressure studies, APPLIED PHYSICS LETTERS, ISSN: 0003-6951, Vol.89, No.5, pp.51902-1-3, 2006
Teisseyre H., Suski T., Łepkowski S.P., Perlin P., Jurczak G., Dłużewski P., Daudin B., Grandjean N., Strong electric field and nonuniformity effects in GaN/AlN quantum dots revealed by high pressure studies, APPLIED PHYSICS LETTERS, ISSN: 0003-6951, Vol.89, No.5, pp.51902-1-3, 2006

Abstract:
The photoluminescence (PL) from GaN quantum dots (QDs) embedded in AlN has been investigated under hydrostatic pressure. The measured pressure coefficient of emitted light energy [dE / dP] shows a negative value, in contrast with the positive pressure coefficient of the GaN band gap. We also observed that increasing pressure leads to a significant decrease of the light emission intensity and an asymmetric broadening of the PL band. All these effects are related to the pressure-induced increase of the built-in electric field. A comparison is made between experimental results and the proposed theoretical model which describes the pressure behavior of nitride QDs.

Keywords:
III-V semiconductor, Quantum dot, Piezoelectricity, Photoluminescence

14.Dłużewski P., Nonlinear field theory of stress induced diffusion in crystalline solids, DEFECT AND DIFFUSION FORUM, ISSN: 1662-9507, DOI: 10.4028/www.scientific.net/DDF.237-240.107, Vol.237-240, pp.107-114, 2005
Dłużewski P., Nonlinear field theory of stress induced diffusion in crystalline solids, DEFECT AND DIFFUSION FORUM, ISSN: 1662-9507, DOI: 10.4028/www.scientific.net/DDF.237-240.107, Vol.237-240, pp.107-114, 2005

Keywords:
Chemical Strain, Dislocation Climbing, Driving Force, Interdiffusion, Kirkendall Effect, Molar Derivative, Molar Motion, Vacancy

15.Dłużewski P., Kontynualna teoria dyslokacji jako teoria konstytuwnego modelowania skończonych sprężysto-plastycznych deformacji (Praca habilitacyjna), Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.13, pp.1-112, 1996
16.Dłużewski P., Zastosowanie teorii poślizgów do opisu procesów deformacji niesprężystych (Praca doktorska), Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.37, pp.1-91, 1985

Lista rozdziałów w ostatnich monografiach
1.
399
Jurczak G., Maździarz M., Dłużewski P., Nanomechanics: Selected problems, rozdział: Atomistic-continuum modelling of coupled fields and defects in semiconductor crystals, Wydawnictwa Politechniki Krakowskiej , pp.77-98, 2014
2.
3
Dłużewski P., Young T.D., Dimitakopulos G., Kioseoglou J., Komninou Ph., Computer Methods in Mechanics, Advanced Structured Materials, rozdział: Nonlinear finite element and atomistic modelling of dislocations in heterostructures, Springer Verlag, Kuczma M., Wilmański K. (Eds.), 1/III, pp.239-253, 2010
Redaktor monografii
1.
425
Dłużewski P., Jurczak G., Young T.D., Book of abstracts of 3rd International Conference on Material Modelling incorporating 13th > European Mechanics of Materials Conference, IPPT PAN, pp.-, 2013

Prace konferencyjne
1.Jurczak G., Young T.D., Dłużewski P., A quantum dot nucleated on the edge of a threading dislocation: elastic and electric field effects, PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, ISSN: 1610-1642, DOI: 10.1002/pssc.201200551, Vol.10, pp.97-100, 2013
Jurczak G., Young T.D., Dłużewski P., A quantum dot nucleated on the edge of a threading dislocation: elastic and electric field effects, PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, ISSN: 1610-1642, DOI: 10.1002/pssc.201200551, Vol.10, pp.97-100, 2013

Abstract:
In this work the affect of a threading dislocation localised on the edge of GaN/AlN quantum dot is analysed. A standard piezoelectric continuum model is extended to allow the embodiment of threading dislocations that are modelled as a continuous electro-elastic line defect originating in the matrix material. Two common types of dislocation are considered: an edge-type and a screw-type.

It is demonstrated that the presence of a TD provides local region of tensile strain as a preferential condition for GaN QD growth by reduction of the GaN / AlN lattice mismatch. It is found that dislocation induced potential causes a measurable in-plane shift of the electron/hole localisation and an asymmetric decrease in the band-to-band transition energy.

Keywords:
quantum dot, threading dislocation, piezoelectricity, band edge structure

10p.
2.Maździarz M., Nalepka K.T., Dłużewski P., Cholewiński J., Reconstruction of dislocations in interface layer Cu-Al2O3, MMM2010, 5th International Conference Multiscale Materials Modeling, 2010-10-04/10-08, Freiburg (GE), pp.482-485, 2010
Maździarz M., Nalepka K.T., Dłużewski P., Cholewiński J., Reconstruction of dislocations in interface layer Cu-Al2O3, MMM2010, 5th International Conference Multiscale Materials Modeling, 2010-10-04/10-08, Freiburg (GE), pp.482-485, 2010

Abstract:
Using three different methods namely, CDT (Continuous Dislocation Theory), molecular TB - SMA (Tight Binding Second Moment Approximation) type many - body potential, and MEM (Molecular Effective Medium) theory, we are looking for the best possible reconstruction of dislocations in Cu - Al 2 O 3 heterostructure.

3.Dłużewski P., Young T.D., Jurczak G., Majewski J.A., Nonlinear piezoelectric properties of GaN quantum dots nucleated at the edge of threading dislocations, IWN 2006, International Workshop on Nitride Semiconductors, 2006-10-22/0-27, Kyoto (JP), DOI: 10.1002/pssc.200674866, Vol.4, pp.2399-2402, 2007
Dłużewski P., Young T.D., Jurczak G., Majewski J.A., Nonlinear piezoelectric properties of GaN quantum dots nucleated at the edge of threading dislocations, IWN 2006, International Workshop on Nitride Semiconductors, 2006-10-22/0-27, Kyoto (JP), DOI: 10.1002/pssc.200674866, Vol.4, pp.2399-2402, 2007

Abstract:
It was observed experimentally by Rouviere et al. that GaN/AlN Quantum Dots (QDs) nucleate at the edge of threading dislocations (Appl. Phys. Lett. 75, 2632 (1999) [1]). The preferred nucleation of QDs in this way is generally assumed to be due to the influence of the stress/strain field around the dislocation core, which in turn, gives the chemical and geometric conditions for nucleation of the QDs. We solve the finite element problem for QDs situated at the edge of threading dislocations where different lattice parameters, piezoelectric and spontaneous polarisation coefficients are assumed for the QD and its matrix. By solving the elastic and electric equilibrium problems we obtain both the residual stress and electric fields. The computational scheme employed here was obtained by linking two previous finite element algorithms described inreferences (P. Dłu ̇zewski et al., Comput. Mater. Sci. 29, 379 (2004) [2]) and (G. Jurczak et al., phys. stat. sol. (c) 2, 972 (2005) and S.P. Łepkowski et al., Phys. Rev. B 73, 245201 (2005) [3, 4], respectively). This approach allows us to get a deeper physical insight into the mechanics and electrical properties of QDs and ultimately determine the efficiency of light emission from these objects.

Keywords:
Nanostructure, III-V semiconductor, Piezoelectricity, Threading dislocation

4.Dłużewski P., Belkadi A., Chen J., Ruterana P., Nouet G., FE simulation of InGaN QD formation at the edge of threading dislocation in GaN, IWN 2006, International Workshop on Nitride Semiconductors, 2006-10-22/0-27, Kyoto (JP), DOI: 10.1002/pssc.200674870, Vol.7, pp.2403-2406, 2007
Dłużewski P., Belkadi A., Chen J., Ruterana P., Nouet G., FE simulation of InGaN QD formation at the edge of threading dislocation in GaN, IWN 2006, International Workshop on Nitride Semiconductors, 2006-10-22/0-27, Kyoto (JP), DOI: 10.1002/pssc.200674870, Vol.7, pp.2403-2406, 2007

Abstract:
The stress induced diffusion process of In-Ga segregation in InxGa1–xN layer deposited on GaN is simulated step by step by using a 3D nonlinear FE method. From the thermodynamical point of view this process is governed by the driving force induced by the gradient of residual stresses operating in an anisotropic nonlinear elastic structure. The source of stresses we consider is the set of threading dislocations examined in the plane view HRTEM investigation of GaN layer deposited on sapphire.

5.Postek E.W., Hardy S.J., Dłużewski P., Stress analysis of a quantum dot region using an elastic anisotropic model, Plasticity 2006, 12th International Symposium on Plasticity and Its Current Applications, 2006-07-17/07-22, Halifax (CA), pp.304-306, 2006
6.Jurczak G., Łepkowski S.P., Dłużewski P., Suski T., Modeling of elastic, piezoelectric and optical properties of vertically correlated GaN/AlN quantum dots, E-MRS 2004, Symposium on Science and Technology of Nitrides and Related Materials/Wide Band Gap II-VI Semiconductors, E-MRS 2004 FALL MEETING SYMPOSIA C AND F, 2004-08-06/08-10, Warszawa (PL), DOI: 10.1002/pssc.200460604, Vol.2, No.3, pp.972-975, 2005
Jurczak G., Łepkowski S.P., Dłużewski P., Suski T., Modeling of elastic, piezoelectric and optical properties of vertically correlated GaN/AlN quantum dots, E-MRS 2004, Symposium on Science and Technology of Nitrides and Related Materials/Wide Band Gap II-VI Semiconductors, E-MRS 2004 FALL MEETING SYMPOSIA C AND F, 2004-08-06/08-10, Warszawa (PL), DOI: 10.1002/pssc.200460604, Vol.2, No.3, pp.972-975, 2005

Abstract:
We theoretically investigate elastic, piezoelectric and optical properties of wurtzite GaN/AlN quantum dots, having hexagonal pyramid-shape, stacked in a multilayer. We show that the strain existing in quantum dots and barriers depends significantly on the distance between the dots i.e. on the width of AlN barriers. Drop of the electrostatic potential in the quantum dot region slightly increases with increasing of the barrier width. This increase is however much smaller for QDs than for superlattice of quantum wells. Consequently, band-to-band transition energies in the vertically correlated quantum dots show rather weak dependence on the width of AlN barriers.

Keywords:
III-V semiconductor, quantum dot, piezoelectricity, elastic strain, electrostatic potential


Abstrakty konferencyjne
1.Dłużewski P., Maździarz M., Tauzowski P., Constitutive and FE modeling of Residual Stresses and Kirkendall Effect in Semiconductor Structures, 4th International Conference on Material Modeling, 2015-05-27/05-29, Berkeley (US), pp.79-80, 2015
Dłużewski P., Maździarz M., Tauzowski P., Constitutive and FE modeling of Residual Stresses and Kirkendall Effect in Semiconductor Structures, 4th International Conference on Material Modeling, 2015-05-27/05-29, Berkeley (US), pp.79-80, 2015

Abstract:
The interdiffusion of chemical components coupled with vacancy movement can cause void formation and/or spinodal decomposition in crystal growth. In the case of SiC growth on Si, the higher mobility of Si atoms compared to C results in the migration of SiC/Si interface and formation of voids in the substrate in some thermodynamic conditions. In the case of In -rich InGaN layers deposited on GaN a precipitation of metallic indium bordering with voids is observed. In the current approach we consider interdiffusion, lattice distortion and chemical maps extracted from HRTEM images of SiC/Si and InGaN/GaN. Dislocations and void surface are treated as local regions of nucleation and annihilation of the vacancies transporting the mass in FE mesh. In result, the interface and FE mesh are convected with the crystal lattice drift. In the constitutive modeling applied [1] the lattice strain and the atom fraction of chemical component are used as two independent thermodynamic variables. Due to climbing of misfit dislocations the plastic distortion tensor field is taken into account in the form of additional nodal variables. This tensor field is spanned on corner nodes of Lagrangian finite elements (FE) which gives the possibility for reconstruction of the atomistic model of dislocation network interpenetrating the considered FE mesh [2,3]. The chemo-mechanical coupling is based on the use of Vegard's law formulated in terms of Biot strain. Due to the logarithmic strain applied in hyperelastic modeling, some transformation rule is considered for Vegard's law. This rule allowed us to eliminate artificial residual stresses yielding from incompatibe fields of the atom fraction and plastic distortions spanned on nodes by means of shape functions [2]. In the case of single finite elements, the mentioned approach allowed us to reduce spurious stresses in integration points from the level 100 MPa to 10^ -5 MPa, while at the same time holding the stress components yielding from Vegard's law at the level of 1 GPa (relaxed by plastic distortions).

Keywords:
Constitutive modelling, Finite Element Method

2.Dłużewski P., Tauzowski P., The FE modelling of residual stresses and void formation observed during the growth of semiconductor layers, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.553-554, 2015
Dłużewski P., Tauzowski P., The FE modelling of residual stresses and void formation observed during the growth of semiconductor layers, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.553-554, 2015

Abstract:
In the current approach we consider interdiffusion, lattice distortions and chemical maps corresponding the growth of SiC/Si and In- GaN/GaN layers. Dislocations and free surfaces are treated as local regions for nucleation and annihilation of the vacancies transporting the mass between finite elements (FEs). In result, the interface and FE mesh are convected with the crystal lattice drift. In the constitutive modelling applied [1] the lattice distortion and the Si and vacancy molar fractions are used as independent nodal variables. Due to the climbing down of misfit dislocations the plastic distortion tensor field is taken into account in the form of additional nodal variables. This tensor field is spanned on corner nodes of the second order Lagrangian finite elements [2]. The chemo-mechanical coupling is based on the use of Vegard’s law formulated alternatively in terms of Biot or Hencky strains. Due to the logarithmic strain applied in hyperelastic modelling, some transformation rule is considered for Vegard’s law. This rule allowed us to eliminate artificial residual stresses yielding from incompatibility of the fields of atom fraction and plastic distortions spanned by means of the same shape functions on the corner nodes.

Keywords:
residual stresses, Kirkendall effect, diffusion, mass transport, semiconductor layers, crystal growth

3.Dłużewski P., Maździarz M., Tauzowski P., Third-order elastic coefficients and logarithmic strain in finite element modelling of anisotropic elasticity, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.35-36, 2014
Dłużewski P., Maździarz M., Tauzowski P., Third-order elastic coefficients and logarithmic strain in finite element modelling of anisotropic elasticity, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.35-36, 2014

Abstract:
Contrary to higher order elastic constants for momentum stresses the second (classical) and third-order elastic coefficients (TOEC) for symmetric elasticity are measured and tabulated successfully with good accuracy for tens of years. In the classical experimental measurements of TOEC, the correct recalculation of instantaneous stiffness changes onto TOEC has an important role. A similar problem arises in the constitutive and finite element (FE) modelling. Namely, because of a very strong dependency of TOEC on the strain measure choice, the constitutive and FE modelling of elastic materials is considered here in terms of different finite strain measures. To this aim, the known analytical formulae for calculation of two first derivatives of the isotropic tensor function of tensor variable are verified by means of the finite difference method. In result, the revised formulae are used for calculation of the tangent stiffness matrix. This paper closes with some remarks on the use of TOEC in finite element modelling.

Keywords:
nonlinear elasticity, third-order elastic coefficients, logarithmic strain

4.Jurczak G., Young T.D., Dłużewski P., Dimitrakopulos G.P., Elastic and electric properties of a semi-polar (1122) GaN/AlN quantum dots, ICMM3, 3rd International Conference on Material Modelling incorporating 13th European Mechanics of Materials Conference, 2013-09-08/09-11, Warszawa (PL), pp.243-244, 2013
Jurczak G., Young T.D., Dłużewski P., Dimitrakopulos G.P., Elastic and electric properties of a semi-polar (1122) GaN/AlN quantum dots, ICMM3, 3rd International Conference on Material Modelling incorporating 13th European Mechanics of Materials Conference, 2013-09-08/09-11, Warszawa (PL), pp.243-244, 2013

Keywords:
Semiconductor, Quantum dot, Piezoelectricity, Band-edge structure

5.Jurczak G., Maździarz M., Dłużewski P., Effect of threading dislocation on elastic and electric properties of semipolar GaN/AlN quantum dot, ICMM3, 3rd International Conference on Material Modelling incorporating 13th European Mechanics of Materials Conference, 2013-09-08/09-11, Warszawa (PL), pp.186-187, 2013
Jurczak G., Maździarz M., Dłużewski P., Effect of threading dislocation on elastic and electric properties of semipolar GaN/AlN quantum dot, ICMM3, 3rd International Conference on Material Modelling incorporating 13th European Mechanics of Materials Conference, 2013-09-08/09-11, Warszawa (PL), pp.186-187, 2013

Keywords:
Semiconductor, Piezoelectricity, Dislocation

6.Young T.D., Teisseyre H., Dłużewski P., Kahouli A., Kriouche N., Brault J., Damilano B., Leroux M., Courville A., de Mierry P., GaN/AlGaN (11-22) semipolar nanostructures: Observations by theory and experiment, 41st International School and Conference on the Physics of Semiconductors, 2012-06-08/06-15, Krynica-Zdrój (PL), 2012
7.Kret S., Bilska M., Ivaldi F., Leszczyński M., Czernecki R., Dłużewski P., Jurczak G., Young T.D., Determination of the nanoscale structural properties of the InAlN based devices by advanced TEM methods, E-MRS 2012 FALL MEETING, 2012-09-17/09-21, Warszawa (PL), 2012
Kret S., Bilska M., Ivaldi F., Leszczyński M., Czernecki R., Dłużewski P., Jurczak G., Young T.D., Determination of the nanoscale structural properties of the InAlN based devices by advanced TEM methods, E-MRS 2012 FALL MEETING, 2012-09-17/09-21, Warszawa (PL), 2012

Keywords:
III-V semiconductors, piezoelectricity, high resolution transmission electron microscopy, band edge structure

8.Jurczak G., Young T.D., Dłużewski P., Elastic and Electric Field Effects of a Quantum Dot Nucleated on the Edge of a Threading Dislocation, EDS 2012, International Conference on Extended Defects in Semiconductors, 2012-06-24/06-29, Thessaloniki (GR), pp.103, 2012
Jurczak G., Young T.D., Dłużewski P., Elastic and Electric Field Effects of a Quantum Dot Nucleated on the Edge of a Threading Dislocation, EDS 2012, International Conference on Extended Defects in Semiconductors, 2012-06-24/06-29, Thessaloniki (GR), pp.103, 2012

Keywords:
quantum dot, threading dislocation, piezoelectricity, band edge structure

9.Young T.D., Jurczak G., Dłużewski P., Wpływ defektów struktury krystalicznej na elektromechaniczne własności nanostruktur, III National Conference of Nano and Micromechanics, 2012-07-04/07-06, Warszawa (PL), pp.125-127, 2012
Young T.D., Jurczak G., Dłużewski P., Wpływ defektów struktury krystalicznej na elektromechaniczne własności nanostruktur, III National Conference of Nano and Micromechanics, 2012-07-04/07-06, Warszawa (PL), pp.125-127, 2012

Keywords:
Piezoelektryczność, Mechanika Ośrodków Ciągłych, Metoda Elementów Skończonych, Nanostruktura

10.Young T.D., Teisseyre H., Brault J., Kahouli A., Vennegues P., Leroux M., Courville A., de Mierry P., Damilano B., Dłużewski P., Optoelectronic properties of a GaN quantum dot grown on a Al0.5Ga0.5N (1122)-orientated surface, IWN 2012, International Workshop on Nitride Semiconductors, 2012-10-14/10-19, Sapporo (JP), pp.1-2, 2012
11.Dłużewski P., Cholewiński J., Maździarz M., Tauzowski P., Nalepka K.T., Atomistic/continuum reconstruction of misfit dislocations and stacking faults in Cu/sapphire interfacial region, CMM 2011, 19th International Conference on Computer Methods in Mechanics, 2011-05-09/05-12, Warszawa (PL), pp.257-1-2, 2011
Dłużewski P., Cholewiński J., Maździarz M., Tauzowski P., Nalepka K.T., Atomistic/continuum reconstruction of misfit dislocations and stacking faults in Cu/sapphire interfacial region, CMM 2011, 19th International Conference on Computer Methods in Mechanics, 2011-05-09/05-12, Warszawa (PL), pp.257-1-2, 2011

Abstract:
A method for reconstruction of atomistic models of dislocations and stacking faults in the interfacial region of heterostructures is presented. Its mathematical foundations come back to the algebra of the finite deformation fields related to introducing of discrete dislocations into an initially coherent interface. From the practical point of view the method concerns generation of interfacial regions with misfit/treading partial dislocations and stacking faults being formed in the interfacial region between crystal structures of different crystallographic type.

Keywords:
atomistic models, dislocations, stacking faults, lattice distortion