• Composites Research
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• 제24권3호
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• pp.17-24
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• 2011

Ag/Cu층에서 발생하는 misfit 전위를 분석하기 위하여, EAM기법을 활용한 나노인덴테이션 해석을 수행하였다. N$\'{o}$se-Hoover 서모스텟 조건에 의거하여, 2-5nm 정도의 두께를 갖는 필름층에 구형 인덴터로 압입하였다. 해석결과는 misfit 전위에 대한 상대적인 압입위치가, 4nm이하의 필름에 대하여 영향을 미치는 것으로 나타났다. 전위에 의한 슬립 발생할 때 탄성에너지 변화는 Ag/Cu의 연화의 중요한 변수로 작용하며, 각각의 경우에 대하여 임계필름두께에 대해서도 고찰하였다.

• Applied Microscopy
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• 제27권4호
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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.

• Applied Microscopy
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• 제36권spc1호
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1794-1799
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• 2008

The effect of misfit on the indentation behaviour of silver coated copper multilayer was studied by molecular dynamics simulation. It was found that the misfit bands on interface formed by the mismatch of lattice structure between copper and silver in slip direction [110] and the dislocation band width depended on the mismatched lattice constants of materials. More dislocations were created and glided by indentation, which created a "four-wing flower" structure consisting of pile. up of dislocation at the interface. The size of "flower" depended on the thickness of silver layer. The critical thickness for "flower" was approximately 4nm above which the "flower" disappeared. As the result, deformation mechanisms such as dislocation pile-up, dislocation cross-slip and movement of misfit dislocation were revealed. Only silver atoms in the dislocation pile-up were involved in the creation of the "flower" while the dislocations in copper were glided in slip direction on interface.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.298-303
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• 2001

The critical thickness of an epitaxial film on a substrate in electronic or optoelectronic devices is studied on the basis of equilibrium dislocation analysis. Two geometric models, a single dislocation and an array of dislocations in heteroepitaxial system, are considered respectively to calculate the misfit dislocation formation energy. The isotropic linearly elastic stress fields for the models are obtained by means of complex potential method combined with alternating technique, and are used for calculating the formation energies. As a result, the effect of elastic mismatch between film and substrate on critical thickness is presented and $Si_xGe_{1-x}/Si$ epitaxial structure is analyzed to predict the critical thickness with varying germanium concentration.

• 한국전기전자재료학회논문지
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• 제30권12호
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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.

• 한국재료학회지
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• 제19권12호
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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.

• 전자공학회논문지A
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• 제30A권8호
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• pp.42-48
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• 1993

Ar ions were implanted at 1 MeV into (100)Cz Si wafers with dose of 1 * 10$^{15}$ ions/cm$^{2}$. Damage induced by high energy implantation and its annealing behavior during rapid thermal annealing for 10sec at temperatures from 550 to 1100${\circ}C$ were investigated by crosssection transmission electron microscopy study. It can be clearly seen from the observation that the SPE(Solid Phase Epitaxy) regrowth of the buried amorphous layer induced by ion implantation proceeds from both upper and lower amorphous/crystalline (a/c) interfaces, and the activation energy for SPE from interfaces were both 1.43eV. Misfit dislocation where two interfaces met was formed and it coalesced into the hair pin dislocation in the upper regrown region. At the higher temperature after annealing out of the misfit dislocation, hair pin dislocations showed considerable drop in its bandwidth. However, they were not disappeared even at the temperature 1100${\circ}C$ with the end of range dislocation loops which were formed at the original lower a/c interface.

• Composites Research
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• 제22권3호
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• pp.9-17
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• 2009

본 논문에서는 분자동력학 방법을 이용하여 Ag 필름/Cu기판에 대한 나노인덴테이션 특성을 파악하였다. 필름의 강성과 경도는 필름의 두께에 관계되어있으며, 임계범위 내에서, 그래인 크기가 증기하면 강성과 경도도 증가하는 것을 확인하였다. 5nm 두께 이하의 Ag필름/Cu기판의 강성과 경도는 벌크 Ag의 경우에 비해 낮은 값을 나타내었다. 특히 4nm 두께 이하의 Ag필름/Cu기판의 인덴테이션에 있어서, 전위 집적과 불일치 전위사이의 상호작용에 의해 계면상에서 꽃모양의 전위 루프가 발생 하였다. 이는 인덴테이션 하중과 변위 커브에서 하중이 저하되는 것과 관계있는 것으로 사료되고 있다.

• 전자공학회논문지A
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• 제33A권2호
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• pp.96-113
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• 1996

고농도로 붕소가 도핑된 실리콘층 내에 존재하는 부정합 전위는 웨이퍼 가장자리에서 발생됨을 알았으며, 이 층을 도핑되지 않은 영역으로 둘러쌓음으로써 부정합 전위가 억제된 고농도로 붕소가 도핑된 실리콘층을 형성할 수 있었다. 이를 이용하여 부정합 전위가 없는 고농도로 붕소가 도핑된 실리콘 멤브레인을 제작하였으며, 이 멤브레인의 표면 거칠기 및 파괴 강도 그리고 잔류 인장 응력을 각각 20$\AA$ 1.39${\times}10^{10}dyn/cm^{2}$ 그리고 2.7${\times}10^{9}dyn/cm^{2}$로 측정되었다. 반면에 부정합 전위를 포함하는 기존 멤브레인은 각각 500$\AA$ 8.27${\times}10^{9}dyn/cm^{2}$ 그리고 9.3${\times}10^{8}dyn/cm^{2}$로 측정되었으며, 두 멤브레인의 이러한 차이는 부정합 전위에서 기인함을 알았다. 측정된 두 멤브레인의 Young's 모듈러스는 1.45${\times}10^{12}dyn/cm^{2}$로 동일하게 나타났다. 또, 도핑 농도 1.3${\times}10^{12}dyn/cm^{3}$에 대한 고농도로 붕소가 도핑된 실리콘의 유효 격자 상수 및 기존 멤브레인의 평면적 격자 상수 그리고 기존 멤브레인 내의 부정합 전위의 밀도는 각각 5.424$\AA$ 5.426$\AA$ 그리고 2.3${\times}10^{4}$/cm 로 추출되었으며, 붕소가 도핑된 실리콘의 부정합 계수는 1.04${\times}10^{23}$/atom으로 추출되었다. 한편 별도의 추가적인 공정없이 일반적인 에피 성장법을 사용하여 고농도로 붕소가 도핑된 실리콘층 위에 부정합 전위가 없는 에피 실리콘을 성장시켰으며, 이 에피 실리콘의 결정성은 매우 양호한 것으로 밝혀졌다. 또 부정합 전위가 없는 에피 실리콘에 n+/p 게이트 다이오드를 제작하고 그 전압-전류 특성을 측정한 결과 5V의 역 바이어스에서 0.6nA/$cm^{2}$의 작은 누설 전류값을 나타내었다.