• Journal of the Korean Society for Nondestructive Testing
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• v.14 no.3
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• pp.157-171
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• 1994

A scanning tunneling microscope has been built, which can resolve atomic arrangements of conductors and semiconductors in ultra high vacuum below $10^{-11}$ Torr. Its background and operational principles are reviewed and the guide lines in building the scanning tunneling microscope are shown. The results of measurements for highly oriented pyrolytic graphite and Si(111) surface are presented.

• Journal of the KSME
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• v.32 no.5
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• pp.420-428
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• 1992

1980년대부터 새롭게 우리에게 다가온 nm의 세계는 그 동안 마이크로의 기술이 인류에게 가져다 준 성과 이상의 것을 약속하고 있다. Nanoscience와 Nanotechnology라는 용어가 차츰 일상적인 것이 되어가고 있으며 이들 기술을 응용한 제품들이 선을 보이고 있다. STM은, 개발된지 10년이 되는 현 시점에서 다른 분야들에 기술적으로 많은 파급효과를 끼쳤으며 STM자체의 성능도 크게 향상되었다. 앞으로도 성능 향상은 빠른 속도로 진행될 것이며 특히 단순한 측정장치를 넘어 가공과 제조장치로서 크게 기대가 된다. 다양한 형태로 결합된 개별 원자들의 성질을 측정함으 로써 거시적으로 나타나는 여러 복합적인 현상들을 근본적으로 이해할 수 있고 또 nm 수준에 서의 공정제어로 품질 좋은 무결점의 제품 생산을 가능하게 해 줄 것이다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.43-43
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• 2013

붕화질소(hexagonal Boron Nitride, h-BN)위의 그래핀은 산화규소(SiO2) 위에 전사된 그래핀에 비해서 월등한 전기적 특성을 갖는다. 따라서 전자소자의 산업적 응용을 위한 대면적화를 위하여, 그래핀을 붕화질소위에 화학증기증착(CVD) 방법을 통해 직성장시키고, 그 전기적 성질이 산화규소 및 suspended된 그래핀에 비해서 훨씬 더 이상적임을 원자 수준의 공간해상도에서 초고진공 저온 주사형 터널링 현미경(scanning tunneling microscope, STM)을 통해 입증하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2272-2283
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• 1994

In scanning tunneling microscopy, the piezoelectric actuator is popuilarly used in stacked type as it can provide remarkable positioning resolution and stiffness. The actuator, however, exhibits a considerable amount of hystereic nonlinearity, resulting in losses of overall measuring accuracy when a linear model is used for its control and calibration, In this study, a nonlinear model is proposed for predicting the precise relationship between the input connand voltage and the output displacement of the actuator itself, cross-coupled electrical behaviours of the driving circuit with the actuator, and mechanical characteristics of the driven components of the actuator. Finally experimental results prove that the nonlinear model enhances the measuring of scanning tunneling microscopy by an order ten in comparison with a conventional linear model.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.2
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• pp.29-33
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• 2002

Various nanometer-scale structures are fabricated on hydrogen-passivated p-type Si(100) surface by scanning probe microscopy(SPM). The hydrogen-passivation is performed by dipping the samples in diluted 10% HF solution for one min.. Pt alloy wires are used for tips and the tips are made by cutting the wires at 45$^{\circ}$ slanted. Various line features are fabricated in various bias voltage. The optimal structure is the line of about 30 nm width on 1.7V bias voltage and 1 nA tunneling current.  

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.512-517
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• 2006

A reliable linear translation system was constructed. The system has six piezo legs, attached to a main body, holding a hexagonal sapphire rod. The sapphire rod moves either forward or backward with the sequential motion of the piezo legs, driven by characteristic electric voltage waves. The translational system was tested in vertical direction. The speed of the sapphire rod was turned out to be constant during several mm travel. The slowest upward speed was measured to be ${\sim}1.7{\times}10^{-6}m/s$, yielding ${\sim}28.3nm/step$, while the slowest upward speed was ${\sim}3.7{\times}10^{-6}m/s$, with ${\sim}61.7nm/step$, due to gravitational force. The velocity increases linearly, as the amplitude of the voltage waves increases. The linear translation system will be used as a coarse approach part for a scanning tunneling microscope.

• Journal of the Korean Vacuum Society
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• v.22 no.6
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• pp.285-290
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• 2013

Epitaxial graphene on metal substrates provides excellent platforms to study its atomic and electronic structures, and can be grown either by surface segregation of carbon or by chemical vapor deposition. The growth behaviors of the two methods, however, have not been directly compared each other. Here, we studied domain structures of graphene grown by three different methods, surface segregation, post-annealing with adsorbed ethylene, and high-temperature dose of ethylene, using scanning tunneling microscopy. The first two methods resulted in graphene regions with areas of $100nm^2$, whereas the third method showed large area graphene (> $10^4nm^2$) with regular hexagonal Moire patterns, implying that high-temperature dose of ethylene is preferable for further studies on graphene such as additional growth of organic molecules.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1731-1739
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• 1993

An application of Scanning Tunneling Microscopy(STM) is investigated for the measurement of 3-dimensional profiles of the macro-machined patterns of which critical dimensions lie in the range of submicrometers. Special emphasis of this investigation is given to extending the measuring ranges of STM upto the order of several micrometers while maintaining superb nanometer measuring resolution. This is accomplished by correcting hysteresis effects of piezoelectric actuators by using non-linear compensation models. Detailed aspects of design and control of a prototype measurement system are described with some actual measuring examples in which fine It patterns can successfully be traced with a resolution of 1 nanometer over a surface range of $4{\times}2$ micrometers.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.37-44
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• 2006

The homoepitaxy of Si(5 5 12) at $495^{\circ}C$ has been studied by Scanning Tunneling Microscopy under ultrahigh vacuum. A Si-dimer is the basic building-block and preferentially adsorbs on a unique site, that is, the Si-dimer/adatom site at the (337) and the (225) subsections within the Si(5 5 12) unit cell. The Si(5 5 12) unit cell is faceted to $3\times(337)$ subsections filled with Si-addimers and $1\times(113)$ subsection. In this step the tetramer at the other (337) section within the unit cell is transformed to a dimer/adatom site which can accept Si-dimers. Each (337) section is faceted to $1\times(112)\;and\;1\times(113)$, and then finally the unit cell of Si(5 5 12) is faceted to $3\tiems(112)\;and\;4\times(113)$ and forms the facet of effective height, $2.34{\AA}$. In this step, mutual transformation between the honeycomb chain and the dimer/adatom occurs. Finally, the valley between (112) and (113) facets is filled. If once the last step is completed, the uniform and planar Si(5 5 12) terrace is recovered. From the present study, therefore, it can be concluded that the homoepitaxy on Si(5 5 12) is periodically achieved and such growth mode is quite unique since faceting of the substrate-unit-cell plays a critical role for controlling uniformity of the overlayer.