• Korean Journal of Materials Research
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• v.16 no.8
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• pp.473-478
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• 2006

The coherent interface energies and misfit strain energies of Fe/XN (X=Ti, Zr, Hf) systems were calculated by first principles method. The interface energies in Fe/TiN, Fe/ZrN and Fe/HfN systems were 0.343, 0.114, and 0.030 $J/m^2$, respectively. Influence of bond energy was estimated using the discrete lattice plane/nearest neighbor broken bond(DLP/NNBB) model. It was found that the dependence of interface energy on the type of nitride was closely related to changes of the bond energies between Fe, X and N atoms before and after formation of the Fe/XN interfaces. The misfit strain energies in Fe/TiN, Fe/ZrN, and Fe/HfN systems were 0.239, 1.229, and 0.955 eV per 16 atoms(Fe; 8 atoms and XN; 8 atoms). More misfit strain energy was generated as the difference of lattice parameters between the bulk Fe and the bulk XNs increased.

• Korean Journal of Materials Research
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• v.15 no.9
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• pp.566-576
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• 2005

This paper describes an ab Initio study on interface energies, misfit strain energies, and electron structures at coherent interfaces Fe(bcc structure)/MCs(NaCl structure M=Ti, Zr, Hf). The interface energies at relaxed interfaces Fe/TiC, Fe/ZrC and Fe/HfC were 0.263, 0.153 and $0.271 J/m^2$, respectively. It was understood that the dependence of interface energy on the type of carbide was closely related to changes of the binding energies between Fe, M and C atoms before and after formation of the interfaces Fe/MCs with the help of the DLP/NNBB (Discrete Lattice Plane/ Nearest Neighbour Broken Bond) model and data of the electron structures. The misfit strain energies in Fe/TiC, Fe/ZrC and Fe/HfC systems were 0.390, 1.692 and 1.408 eV per 16 atoms(Fe: 8 atoms and MC; 8 atoms). More misfit energy was generated as difference of lattice parameters between the bulk Fe and the bulk MCs increased.

• Interaction and multiscale mechanics
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• v.1 no.1
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• pp.123-142
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• 2008

Current methodologies used for the inference of thin film stresses through curvature measurements are strictly restricted to stress and curvature states which are assumed to remain uniform over the entire film/substrate system. These methodologies have recently been extended to non-uniform stress and curvature states for the thin film subject to non-uniform, isotropic misfit strains. In this paper we study the same thin film/substrate system but subject to non-uniform, anisotropic misfit strains. The film stresses and system curvatures are both obtained in terms of the non-uniform, anisotropic misfit strains. For arbitrarily non-uniform, anisotropic misfit strains, it is shown that a direct relation between film stresses and system curvatures cannot be established. However, such a relation exists for uniform or linear anisotropic misfit strains, or for the average film stresses and average system curvatures when the anisotropic misfit strains are arbitrarily non-uniform.

• Journal of Magnetics
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• v.5 no.1
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• pp.1-3
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• 2000

We have theoretically investigated changes in reflection coefficients induced by misfit strain located near the interface between an iron-yttrium garnet magnetic film and a nonmagnetic gadolinium-gallium garnet substrate in a transverse magneto-optical configuration.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.81-114
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• 1999

The strain, surface and inerfacial energies of III-V ternary systems were calculated for three kinds of structure modes: the Frank-van der Merwe (FM) mode, the Stranski-Krastanov (SK) mode an the Volmer-Wever (VW) mode. The free energy for each mode was estimated as functions of the thickness and composition or lattice misfit. Through comparison of the free energy of each mode, it was found that the thickness-composition phase diagrams of III-V ternary systems can be determined only by considering the balance of the free energy and three kinds of structure modes appear in the phase diagrams. The SK mode appears only when the lattice misfit is large and/or the lattice layer is thick. The most stable structure of the SK mode is a cluster with four lattice layers or minimum thickness on a wetting layer of increasing lattice layers. The VW mode appears when the lattice misfit is large and the lattice layer is thin and only in the InPSb/InP and GaPSb/GaP systems which have the largest lattice misfit of III-V ternary systems. The stable region of the SK mode in the GaPSb/GaP and InPSb/InP phase diagrams is largest of all because the composition dependence of the strain energy of these systems is stronger than that of the other systems. The critical number of lattice layers below which tow-dimensional (2D) layers precede the three-dimensional (3D) nucleation in the SK mode at x=1.0 depnds on the lattice misfit.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.12
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• pp.757-761
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• 2017

The computational fourier-transform moire (CFTM) method has been briefly explained and this method was used to perform strain analysis of a misfit dislocation in a strained $Si/Si_{0.55}Ge_{0.45}$ layer. An essential advantage of the CFTM method is that it does not require unwrapping, such that errors due to improper unwrapping can be excluded. The analysis results revealed that the Si layer was grown with tensile stress on $Si_{0.55}Ge_{0.45}$ and lattice constant of the Si layer along the growth direction was 1.9% smaller than that of $Si_{0.55}Ge_{0.45}$. On the other hand, strain of the misfit dislocation in the strained $Si/Si_{0.55}Ge_{0.45}$ layer was maximum at the dislocation core due to an extra half-plane and the $e_{xx}$ and $e_{yy}$ values were positive and negative, respectively, along the direction of a burgers vector.

• Applied Microscopy
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• v.27 no.4
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• pp.483-488
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• 1997

A misfit dislocation generation in InAs epilayers grown on (001) InP substrates (oriented $2^{\circ}$ off (001) toward the [110] direction) using metalorganic chemical-vapor deposition was studied. The InAs film of 17 nm thickness grown at $405^{\circ}C$ showed the three different arrays of dislocations: a straight orthogonal array to the <110> direction, an array to the >100> direction, and an array tilted by a degree of $5\sim45^{\circ}$ from the [110] direction. All of the dislocations had a/2<101> Burgers vectors inclined $45^{\circ}$ to the interface. Upon annealing at $660^{\circ}C$ the InAs films with 60, 140 and 220 nm thicknesses, most of the misfit dislocations became the Lomer type $(\sim100%)$ oriented exactly along the >110> direction. These misfit dislocation spacings were decreased with increasing the InAs thickness up to 220 nm thickness. This phenomena was interpreted by the relationship between the dislocation interaction energy among parallel misfit dislocations and the opposite remnant InAs epilayer strain energy. The distance between misfit dislocations was measured by transmission electron microscopy.

• Korean Journal of Materials Research
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• v.19 no.12
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• pp.699-702
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• 2009

Due to the importance of the SiGe/Si heterostructure in the fields of thermoelectric and electronic applications, SiGe/Si heterostructures have been extensively investigated. For practical applications, thermal stability of the heterostructure during the thermoelectric power generation or fabrication process of electronic devices is of great concern. In this work, we focused on the effect of thermal annealing on the defect configuration in the SiGe/Si heterostructure. The formation mechanism of planar defects in an annealed SiGe/Si heterostructure was investigated by transmission electron microscopy. Due to the interdiffusion of Si and Ge, interface migration phenomena were observed in annealed heterostructures. Because of the strain gradient in the migrated region between the original interface and the migrated interface, the glide of misfit dislocation was observed in the region and planar defects were produced by the interaction of the gliding misfit dislocations. The planar defects were confined to the migrated region, and dislocation pileup by strain gradient was the origin of the confinement of the planar defect.

• Applied Microscopy
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• v.36 no.spc1
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• pp.41-46
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• 2006

Interfacial atomic structure (chemical structure) of a Pd/ZnO hetero junction was investigated by atomic resolution high voltage transmission electron microscopy (ARHVTEM). A misfit dislocation did not work as a stress accommodation mechanism in the ZnO(0001)/Pd (111) interface. But the periodic stress localization occurred in the ZnO($10\bar{1}0$)/(200) interface. The periodicity of the local strain coincided with that of misfit dislocation. Atomic structure image of the ARHVTEM showed that an atomic arrangement across the interface was in the order of O-Zn-Pd. It was shown that mechanical weakness of the ZnO(0001)/Pd(111) interface against cyclic heating is attributable to the absence of the periodic stress localization of the misfit dislocation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.387-395
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• 1999

The strain, surface and interfacial energies of III-V ternary systems were calculated for three kinds of structure modes: the Frank-van der Merwe(FM) mode, the Stanski-Krastanov(SK) mode and the Volmer-Weber(VW) mode. The free energy for each mode was estimated as functions of thickness and composition or lattice misfit. Through comparison of the free energy of each mode, it was found that the thickness-composition phase diagrams of III-V ternary systems can be determined only by considering the balance of the free energy and three kinds of structure modes appear in the phase diagrams. The SK mode appears only when the lattice misfit is large and/or the lattice layer is thick. The most stable structure of the SK mode is a cluster with four lattice layers or minimum thickness on a wetting layer of increasing lattice layers. The VW mode appears when the lattice misfit is large and the lattice layer is thin and only in the INPSb/InP and GaPSb/GaP system which have the largest lattice misfit of III-V ternary systems. The stable region of the SK mode in the GaPSb/GaP and InPSb/InP phase diagrams is largest of all because the composition dependence of the strain energy of these systems is stronger than that of the other systems. The critical number of lattice layers below which two-dimensional(2D) layers precede the three-dimensional(3D) nucleation in the SK mode at x=1.0 depends on the lattice misfit.