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The paper presents a general solution of the isotropic elasticity problem for the sandwiched inclusion in an elastic cylinder and having axially varying eigenstrain. This problem is relevant in considerations of a cylinder with axially varying thermal expansion coefficient or a nanowire having an axial inhomogeneity of the crystal lattice parameter due to growth and processing conditions. The technique of the solution and the results for the elastic fields and energies of dilatational inclusions with different distribution of eigenstrain, namely, constant, trapezoidal, and diffusion-like, along the axis of the cylinder, are given in full details. The technique explores the axial superpositions of infinitely thin dilatation disks inserted in the cylinder, the elastic fields of which are found in analytical form. In addition, the energies of interfaces separated domains with constant eigenstrains in the cylinder are given. It is demonstrated that the blurring of the eigenstrain in the transition region leads to a decrease in interface energy. [ABSTRACT FROM AUTHOR]

We present a theoretical analysis of the elastic properties of lattice-mismatching axial nanowire heterostructures. In contrast to the previous works, we take into account non-ideal diffuse interfaces between the dissimilar materials, which are often observed in nanowire heterostructures. Another important result is the existence of a maximum of the elastic energy in a double nanowire heterostructure as a function of its height. The obtained results are applicable to a wide range of material combinations and can be used for understanding and controlling the crystal quality and physical properties of nanowire-based heterostructures for different applications. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Presents information pertaining to the domain pattern formation within the epitaxial rhombohedral ferroelectric films. Information on the coherency defects; Reference to the common formation of the domain structures; How the appearance of the domain is generally caused; Consistency of idea approach.

Exploring an approach to grain boundary (GB) mesoscopic structure in 3D polycrystals, we develop a model description for equilibrium and non-equilibrium states of GBs in graphene. Non-equilibrium states of GBs in graphene are analyzed for the first time. On the base of this model, dependence of total energy for symmetric GBs on the misorientation angle, E ( θ ), in graphene was calculated. It was found that for the same average misorientation angle the energy in a non-equilibrium state of a GB in graphene can significantly exceed the energy in the equilibrium state. In graphene, the GB energy depends to a greater extent on the deviation from the equilibrium state than on the misorientation angle. It is proposed to account for the presence of non-equilibrium GBs in the explanations of unusual physical properties of graphene. [ABSTRACT FROM AUTHOR]

Abstract: In this article, we analyze the behavior of threading dislocations in GaN layers re-grown on hexagonally patterned mask-less GaN. The growth mode of the material with patterned hexagonal morphology changes with the diameter and the periodicity of the hexagonal patterns. The growth mode directly affects the shape of the voids that are formed in this kind of lateral epitaxy. Transmission electron microscopy has been used to study threading dislocations in GaN layers with voids having different sizes and sidewall angles. The results show that a significant number of threading dislocations near the tapered void''s surface undergo a 90° reorientation in their propagation trajectory whereas almost no dislocations bend in the case of smaller voids having more vertical sidewalls. Different types of dislocations in the vicinity of the voids have also been identified using the invisibility g·b criteria. The full width at half maximum values for XRD ω-scan recorded in (002) reflection drop from 256″ to 181″ as the void sidewall inclination changes from 85° to 60°. A similar dropping trend in the full width at half maximum values for asymmetric diffraction reflections has also been observed. [Copyright &y& Elsevier]

Abstract: We present the results of GaN re-growth on hexagonally patterned GaN templates. Sapphire was used as the original substrate and the samples were grown by metalorganic vapor phase epitaxy (MOVPE). The re-growth on the patterned templates results in the formation of voids at the GaN/sapphire interface. Our extensive scanning electron microscopy (SEM)-based experimental investigations show that the void shape can be controlled from nearly vertical to fully inclined configurations. It was found that the initial hexagon hole diameter plays a key role in determining the final profile of the void sidewalls. X-ray diffraction analysis of the GaN layers indicates that the layers with inclined sidewall voids have an improved crystalline quality. Knowledge of the void configurations in the GaN layers and a possibility to control their shape can help in enhancing light extraction from the light emitting structures. [Copyright &y& Elsevier]

Abstract: The role of disclinations in deformation behavior and structure formation of nanocrystalline materials (NCMs) is discussed. A short overview of the properties of disclination defects is given. Then a number of disclination-based models is advanced for the explanation of NCM mechanical properties. The relay dislocation–disclination model of plastic shear propagation in NCM is developed in detail. This model is based on the switching between translation and rotation deformation modes of plastic deformation. It is argued that the translation mode in NCM is due to the grain boundary dislocation sliding and the rotation mode is due to the formation of wedge junction disclinations which emerge by co-operation processes of intergrain dislocation motion or co-operative grain boundary diffusion. The dependence of deforming stress on the grain size for various grain aspect ratios is demonstrated in the case of relay dislocation–disclination mechanism operation. It is shown that the transition from one mode to another may contribute to the inverse Hall–Petch relationship observed in NCM below a critical grain size. [Copyright &y& Elsevier]

An overview of recent achievements of the disclination approach in mechanics and physics of solids is given and the use of disclination modeling in materials science is demonstrated. Disclinations are defined as linear defects in solids, which manifest themselves as the sources of characteristic singularities in the fields of displacement and rotation. Necessary terminilogy and designations: Volterra dislocations, Frank (rotation) vector of a disclination, wedge and twist disclinations, are provided and discussed. The properties of screened disclination configurations (loops, dipoles, defects in small particles, etc.) with relatively small energies are considered. The methods and results of calculation of elastic energies for screened disclinations (for example, near a free surface) are presented. On the basis of properties of screened disclinations a series of models for the processes in the structure of plastically deformed materials is developed. The bands with misorientated crystal lattice in metals and other materials are described as a result of partial wedge disclination dipole motion. Disclination models are applied to the analysis of workhardening at large strains and to the theory of grain boundaries and their junctions in polycrystals. Disclination models for the structure and properties of nanostructured materials and nanoparticles are also delivered. Finally, the role of disclinations in relaxation of elastic stresses in epitaxial thin films is highlighted. [Copyright &y& Elsevier]

A recently observed mechanism of elastic stress relaxation in mismatched layers is discussed. The relaxation is achieved by the inclination of pure edge threading dislocation lines with respect to the layer surface normal. The relaxation is not assisted by dislocation glide but rather is caused by the “effective climb” of edge dislocations. The effective dislocation climb may result from the film growth and it is not necessarily related to bulk diffusion processes. The contribution of the dislocation inclination to strain relaxation has been formulated and the energy release due to the dislocation inclination in mismatched stressed layers has been determined. This mechanism explains recently observed relaxation of compressive stresses in the (0001) growth of Al[sub x]Ga[sub 1-x]N layers. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dilatational conical inclusion (CI) is modelled as the set of dilatational infinitesimally thin disks with linearly varying diameter along the cone symmetry axis. • Analytical expressions are presented for total displacements, elastic strains, and stresses of the CI in spherical coordinates with the origin in the cone-apex in the form of the series with Legendre polynomials. • The specific features of an "hourglass" dipole inclusion consisting of two CIs with opposite sign of their eigenstrains are demonstrated. In this article, the analytical solution for the isotropic elasticity problem for the cone-shaped inclusion with dilatational eigenstrain in an infinite medium is given. The conical inclusion is modeled by dilatational infinitesimally thin circular disks distributed continuously along the cone z -axis with the radii of the disks being proportional to z -coordinate. The displacements, strains, and stresses of the conical inclusion are given in spherical coordinates with the origin in the cone-apex in the form of the series with Legendre polynomials. The maps of the displacements and the stresses are presented. A comparison of the displacements of the conical inclusion with the displacements of the finite cylindrical and hemispherical inclusions is provided. It is also shown, as expected, that the energy of the dilatational inclusion does not depend on its shape. In Discussion section, the specific features of an " hourglass " dipole inclusion consisting of two conical inclusions with different sign eigenstrains are demonstrated. [ABSTRACT FROM AUTHOR]

We develop a new technique for finding elastic fields for axisymmetric dilatational inclusions (DIs) in the forms of finite cylinder and truncated sphere, when the DIs and surrounding infinite matrix have the same isotropic elastic moduli. DIs are built of circular dilatational disks distributed continuously along the axis of symmetry. Total displacements of DIs are found by integration of the displacements of a dilatational disk. Then, using the linear elasticity equations, the elastic fields of cylindrical and truncated spherical DIs are derived and written via compact easy-to-read and easy-to-calculate Lipschitz-Hankel integrals and Lur'e series, correspondingly. The independence of the strain energy and the elastic dilatation on the DI shape is confirmed. The effect of the aspect ratio and the shape on the elastic fields of the DIs is analyzed. The elastic model of Janus particle and other possible useful applications of solved problems are discussed. [ABSTRACT FROM AUTHOR]

We present the results on the modelling of structural changes in pentagonal small particles (PSPs) during their growth. We prove that after a certain critical size it becomes energetically favourable for a PSP to form a subsurface layer free of twin boundaries (TBs), which are only typical structural elements for smaller size PSPs. In this layer, the low-angle dislocation boundaries (DBs) are formed. Our calculations of the energy stored in the transformed PSP are based on the disclination model of a PSP, in which the TB junctions, as well as TB–DB junctions are treated as wedge disclinations. [ABSTRACT FROM PUBLISHER]

Abstract: Microstructure development during severe plastic deformation by simple shear is modeled using a disclination model for substructure formation incorporated into the viscoplastic self-consistent (VPSC) polycrystal model. The strain incompatibilities between a homogeneous effective medium and a grain calculated by the VPSC model are assumed to result in an accumulation of disclinations at junctions of the grain. These disclinations are then relaxed by the growth of low-angle dislocation boundaries from the junctions. These boundaries split the grain into smaller, misoriented volumes which with further deformation can lead to its subdivision into new grains. The evolution of misorientation angles between the newly formed grains and the parent with applied straining agrees reasonably well with experimental misorientation angle distributions for geometrically necessary boundaries. Accounting for subgrain boundaries and grain subdivision results in textures after large strains that are more diffuse and lower in intensity than those predicted using standard VPSC modeling. [Copyright &y& Elsevier]

Abstract: The morphological and structural evolution is presented for GaN grown by metalorganic chemical vapor deposition on 25nm thick or 150nm thick AlN initial layers on (0001) 4H and 6H SiC substrates. The 25nm thick AlN on SiC was a rough, partially coalesced film, whereas the 150nm thick AlN on SiC was smooth and was characterized by a step-terrace structure. Both the 25 and 150nm thick AlN layers on SiC were nearly free of elastic strains. For both AlN initial layers, the GaN films grew by a coarse islanding mechanism. Measurement of the GaN (0002) interplanar spacing shows that these islands were largely strain relaxed throughout the growth process. Plan view transmission electron microscopy (TEM) showed a well developed misfit dislocation network at the GaN island/AlN interface. Cross sectional TEM revealed that these islands are free of threading dislocations (TDs) prior to coalescence. A simple, low-angle grain boundary model based on island misorientation at coalescence provides reasonable agreement with TD densities measured using plan view TEM. An electron mobility value as high as 818cm2/Vs has been measured at room temperature confirming a high degree of material quality. [Copyright &y& Elsevier]

A method is proposed for increasing the radiation resistance of semiconductor crystals (Al x Ga 1-x) 2 O 3 , which are promising for creating power electronics and optoelectronic devices for spacecraft performing tasks in near-earth orbits. The effect of the aluminum content on the bandgap in (Al x Ga 1-x) 2 O 3 single crystals grown from a melt by the Czochralski method is investigated. The necessary conditions for the formation of a high-quality seed and subsequent growth of single crystals are achieved by setting temperature gradients at each successive stage of growth. The results of energy-dispersive X-ray spectroscopy analysis and optical transmission spectra of (Al x Ga 1-x) 2 O 3 crystals with an aluminum content from 0 to 7.32% are presented. It is shown that an increase in the aluminum content leads to a monotonic increase in the bandgap from 4.7 eV to 5.0 eV, which provides an increase in radiation resistance. • Aluminum content increase leads to the bandgap enlargement of (Al x Ga 1-x) 2 O 3 crystals. • Bandgap enlargement of the semiconductor material enhances radiation resistance of the one. • Radiation robust wide-bandgap semiconductor materials can be utilized for space applications. • Czochralski method grown bulk (Al x Ga 1-x) 2 O 3 crystals purity depends on temperature gradients at each successive growth stage. [ABSTRACT FROM AUTHOR]

This paper discuss a possibility for using a thin-film functional coating based on transparent conducting thin films of aluminum doped zinc oxide (AZO) as a heat-eliminating material on the surface of a spacecraft. The structure of the functional coating has been chosen taking into account the plasmonic properties of AZO and silver and represents the AZO slabs with embedded silver nanoparticles deposited on AZO layer and AZO slabs with embedded silver nanoparticles deposited on thin film fused quartz layer. The paper contains COMSOL finite element simulations of the scattering cross section for thermal radiation in the IR band in the case the investigated coating deposited on a reflective aluminum film, and absorption cross section in the near UV and visible spectral bands when the coating deposited on silicon solar panels. The calculations demonstrate an increase in the scattering cross-section in the spectral band of blackbody radiation by several orders of magnitude, with the maximum in the scattering spectrum of the AZO slabs/ AZO /Al structure corresponding to the maximum intensity of the blackbody thermal radiation, which has been heated to 100 °C in the case the lattice period of the AZO slabs is equal to the resonance wavelength for AZO. Also an increase in the absorption cross-section of AZO slabs/ AZO /Si structure in visible spectral band is observed corresponding to plasmon absorption of embedded silver nanoparticles. • Plasmon effects in ZnO:Al layers can solve the thermal problems for spacecraft. • ZnO:Al is functional material with plasmon resonances in the near IR spectral band. • ZnO:Al is a heat-eliminating material on the surface of a spacecraft. • Metal nanoparticles embedded into the AZO increase the efficiency of solar panels. [ABSTRACT FROM AUTHOR]

A theoretical model is proposed for stress relaxation in decahedral core-shell nanoparticles through formation of circular prismatic misfit dislocation loops at the core-shell interface. The critical conditions for stress relaxation are determined and discussed in comparison with those for single-crystalline core-shell nanoparticles. It is shown that decahedral core-shell nanoparticles should be less stable with respect to misfit dislocation generation than single-crystalline ones when the lattice parameter of the core is larger than that of the shell. Theoretical results are compared with experimental observations available in the literature and are shown to be in a good agreement with the latter. Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract Theoretical model is suggested which describes the misfit stress relaxation near a misfitting nanowire (NW) having the shape of a long parallelepiped embedded in a nanolayer. The stress relaxation is assumed to occur through the emission of dipoles of edge partial (or perfect) dislocations gliding along the NW face normal to the free surfaces of the nanolayer. The total energy change caused by the dislocation emission is calculated and analyzed in dependence on the distances passed by the dislocations. The energy barriers for the dislocation emission are determined and the equilibrium positions of the dislocations are calculated for different values of the system parameters. It is shown that this mechanism of stress relaxation is rather effective and should be taken into account in development of NW-related technology. [ABSTRACT FROM AUTHOR]

A theoretical model is proposed which describes stress relaxation in decahedral particles by generation of circular prismatic dislocation loops. Providing that the particle size exceeds a certain critical value, the nucleation of circular prismatic dislocation loops becomes an effective channel for residual stress relaxation in the particle. Under these circumstances, the loop expands until it reaches its optimal radius which increases with an increase of the particle radius. It is shown that both the critical particle radius and optimal loop radius strongly depend on the dislocation core energy, as well as on the material properties of the particle. [ABSTRACT FROM AUTHOR]

Here we report on the growth and characterization of β-Ga 2 O 3 bulk crystals and polycrystalline layer on different substrates. Bulk β-Ga 2 O 3 crystals were produced by free crystallisation of gallium oxide melt in sapphire crucible. Transparent single crystals measuring up to 8 mm across were obtained. Good structural quality was confirmed by x-ray diffraction rocking curve FWHM values of ~46″. Young’s modulus, shear modulus and hardness of the β-Ga 2 O 3 crystals were measured by nanoindentation and Vickers microindentation techniques. Polycrystalline β-Ga 2 O 3 films were deposited on silicon and sapphire substrates by sublimation method. It was found that structure and morphology of the films were greatly influenced by the material and orientation of the substrates. The best results were achieved on a -plane sapphire substrates where predominantly (111) oriented films were obtained. [ABSTRACT FROM AUTHOR]

• β-Ga 2 O 3 microparticles synthesized with sol–gel technique demonstrate ellipsoid-shape and the layered internal structure. • Particle size depends non-monotonically on the molar ratio of reacting substances. • Fabricated microparticles demonstrate a resistance to nitric acid. Ellipsoid-shape acid-resistant microparticles of β-Ga 2 O 3 are synthesized as a result of chemical reaction of gallium nitrate and ammonia in an aqueous solution with subsequent annealing of received sediment in air. It is shown that particle size depends in non-monotonous manner on the molar ratio of reacting substances. The maximum value of length and diameter (1718 ± 291 nm and 746 ± 198 nm, respectively) is obtained at ammonia to gallium nitrate ratio of 9:1. A decrease in particle size is observed both with reducing and increasing of the ratio. The particles have a layered structure with layer thickness 30 ± 5 nm. [ABSTRACT FROM AUTHOR]

[Display omitted] • k-Ga 2 O 3 is grown epitaxially on α-Al 2 O 3 with 100 || 1 ¯ 2 1 ¯ 0 , 010 || 1 ¯ 010 and [ 001 ] || [ 0001 ] orientation relationships. • Analytical expressions for describing the stress-strain state and piezoelectric polarizations in films of κ-Ga 2 O 3 /α-Al 2 O 3 and κ-(Al x Ga 1 – x) 2 O 3 /κ-Al 2 O 3 heterostructures taking into account materials anisotropy and various growth orientations are presented. • Heterostructure growth orientations can be used to design mechanical and electrical properties of κ-Ga 2 O 3 film, for example, κ-Ga 2 O 3 /α-Al 2 O 3 heterostructures with exotic (10 1 ¯ 8) , (10 1 ¯ 3) , and (2 1 ¯ 1 ¯ 5) growth planes, and κ-(Al x Ga 1 – x) 2 O 3 /κ-Al 2 O 3 heterostructures with ordinary (0 1 0) and (1 0 0) growth planes can be characterized by a low level of internal stresses and low or zero values of strain-induced piezoelectric polarization in the film. The experimental data on orientation relationships for halide vapor phase epitaxy (HVPE) κ-Ga 2 O 3 film grown on (0001) α-Al 2 O 3 substrate and the theoretical model that describes growth orientation dependences of stress–strain state and piezoelectric polarization in κ-(Al x Ga 1- x) 2 O 3 films with orthorhombic crystal structure grown on α-Al 2 O 3 and κ-Al 2 O 3 substrates are presented. Two possibilities for variation in films growth orientation for κ-Ga 2 O 3 /α-Al 2 O 3 and κ-(Al x Ga 1– x) 2 O 3 /κ-Al 2 O 3 heterostructures with inclination axes about either [1 0 0] or [0 1 0] crystallographic directions are considered. The changes in elastic strain field and piezoelectric polarization in the film caused by the differences in values of lattice parameters, elastic, and piezoelectric constants are demonstrated. The growth planes for κ-Ga 2 O 3 /α-Al 2 O 3 and κ-(Al x Ga 1– x) 2 O 3 /κ-Al 2 O 3 heterostructures that are characterized by low internal stresses and low or zero values of piezoelectric polarization are found. [ABSTRACT FROM AUTHOR]

Linear elasticity problem for a straight wedge disclination, which axially pierces a hollow sphere (a spherical layer), is solved analytically. The disclination displacements, stresses and dilatation are given in the form of series with Legendre polynomials. The related elasticity problems for a wedge disclination in a bulk elastic sphere and those one treading a spherical cavity are addressed, as well. It is demonstrated that the found solutions satisfy the boundary conditions on spherical free surfaces including the disclination emerging points. The distribution and the magnitude of the disclination elastic fields in spherical bodies strongly depend on the presence and the size of the inner cavity. For the correct treatment of elasticity for a disclination penetrating through a spherical pore, it is necessary to take into account strictly the boundary conditions on the remote external boundaries of the elastic body. [ABSTRACT FROM AUTHOR]

A TEM study of defect structure of GaN films grown by chloride vapor-phase epitaxy (HVPE) on GaN/Al 2 O 3 substrates was performed. The substrates were fabricated by metal-organic chemical vapor deposition overgrowth of templates with buried column pattern. The results of TEM study showed that the character of the defect structure of HVPE-grown films was determined by the configuration of the column pattern in the substrate. By choosing the proper pattern, the reduction in the density of threading dislocations in the films by two orders of magnitude (in respect to the substrate material), down to the value of 10 7 cm −2 , was achieved. [ABSTRACT FROM AUTHOR]

We report on Ga 2 O 3 deposition on c-plane sapphire substrates by hydride vapour phase epitaxy using metallic gallium, hydrogen chloride and dry air as precursors. High deposition rate up to 250 µm/h has been realized. As confirmed by X-ray diffraction and micro-Raman measurements, produced films consisted of pure monoclinic β-Ga 2 O 3 phase and were (−201) oriented. The full width at half maximum (FWHM) for (−201) rocking curve was decreasing with increasing GaCl flow. The narrowest FWHM of 20 arcmin has been detected. [ABSTRACT FROM AUTHOR]

We describe structural and phase transformation in copper coatings made of microparticles during heating and annealing in air in the temperature range up to 400 °C. Such thermal treatment is accompanied by intensive CuO nanowhisker growth on the coating surface and the formation of the layered oxide phases (Cu 2 O and CuO) in the coating interior. X-ray diffraction and focused ion beam (FIB) are employed to characterize the multilayer structure of annealed copper coatings. Formation of volumetric defects such as voids and cracks in the coating is demonstrated. [ABSTRACT FROM AUTHOR]

A theoretical model is developed that describes stress relaxation in icosahedral small particles through generation of circular prismatic dislocation loops. It is shown that loop generation is energetically favorable in the equatorial section of the particle, the radius of which is larger than the critical one. The dislocation loop then extends until it reaches its optimal radius which increases with particle size. Both the critical particle radius and optimal loop radius strongly depend on dislocation core energy. [ABSTRACT FROM AUTHOR]

We present experimental facts on the role of electrolyte pH in shape control of electrodeposited small silver microcrystals. Increasing electrolyte pH value, i.e. the transition from acidic to alkali solutions, causes the change of microcrystal habitus from strongly distorted (pH ∼ 4) through faceted (pH ∼ 7) to smooth hemispheric (pH ∼ 10) ones. At neutral pH ∼ 7 the observed silver microcrystals demonstrated shapes with pentagonal symmetry including icosahedral microcrystals with incoming pentagonal facets at the icosahedron vertices that is unique for single-component small metallic particles. Such faceting has previously been reported only for bicompounent B6O icosahedral small particles [H. Hubert et al., Nature 391, 376 (1998)]. [ABSTRACT FROM AUTHOR]

A theoretical model is suggested to determine the critical conditions for generation of circular prismatic misfit dislocation loops in hollow core–shell nanoparticles. Based on a strict solution of the linear elasticity boundary-value problem for a circular prismatic dislocation loop in a free-surface shell, we examine the loop formation energy in the nanoparticle and show a potential opportunity to fabricate hollow, coherently bonded, i.e. dislocation-free, core–shell nanoparticles by using thin-wall shells with inner-to-outer radii ratio >0.8 as supporting cores. [Copyright &y& Elsevier]

Abstract: We present a solution to the boundary-value problem in the classical theory of elasticity for a circular prismatic dislocation loop (CPDL) in an elastic body with one or two spherical free surfaces such as a spherical particle, an infinite body with a spherical cavity, and a spherical shell of finite thickness. The axisymmetric position of the CPDL with respect to the spherical surfaces is assumed. Elastic stresses, dilatation and strain energy of the loop are presented in a concise and transparent form of the series with the Legendre polynomials, numerically calculated and illustrated by corresponding maps, and discussed in detail. It is shown that the stress and dilatation fields are strongly screened and distorted by the internal and external free surfaces of the systems under consideration as compared with the case of an infinite medium. The dilatation can change its sign in the subsurface layers of the particle, near the cavity and in the shell. Features of CPDL strain energy are discussed in detail for the cases when the loop experiences the influence of spherical free surfaces. [Copyright &y& Elsevier]

Abstract: A real-time nanomanipulation technique inside a scanning electron microscope (SEM) has been used to investigate the elastic and frictional (tribological) properties of zinc oxide nanowires (NWs). A NW was translated over a surface of an oxidised silicon wafer using a nanomanipulator with a glued atomic-force microscopic tip. The shape of the NW elastically deformed during the translation was used to determine the distributed kinetic friction force. The same NW was then positioned half-suspended on edges of trenches cut by a focused ion beam through a silicon wafer. In order to measure Young’s modulus, the NW was bent by pushing it at the free end with the tip, and the interaction force corresponding to the visually observed bending angle was measured with a quartz tuning fork force sensor. [Copyright &y& Elsevier]

An approach for understanding the cross-hatch morphology in lattice mismatched heteroepitaxial film growth is developed. It is argued that both strain relaxation associated with misfit dislocation formation and lateral surface step flow are required for the appearance of mesoscopic scale surface undulations during layer growth. The results of Monte Carlo simulations for dislocation assisted strain relaxation and consequent film growth predict the development of cross-hatch patterns with a characteristic surface undulation magnitude ∼50 Å in an approximately 70% relaxed In[sub 0.25]Ga[sub 0.75]As layers. This is supported by atomic force microscopy observations of cross-hatch morphology in the same composition samples grown well beyond the critical thickness for misfit dislocation formation. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]