Author
Seungho Park
Bio: Seungho Park is an academic researcher from Hongik University. The author has contributed to research in topics: Thin film & Crystallization. The author has an hindex of 14, co-authored 76 publications receiving 729 citations.
Topics: Thin film, Crystallization, Laser, Amorphous silicon, Molecular dynamics
Papers published on a yearly basis
Papers
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TL;DR: In this article, the motion of nanoscale structures made of pure crystalline silicon with different lattice conditions is simulated in vacuum by applying the molecular dynamics technique with the use of the Tersoff potential.
88 citations
TL;DR: In this paper, the surface tension of bubbles and their properties were investigated using the molecular dynamics (MD) simulation method for their properties owing to their inherent difficulties, and a stable bubble regime with respect to simulation domain sizes was defined for the Lennard-Jones molecules.
70 citations
TL;DR: In this article, the authors proposed a double scan technique that measures temperature only from the heat transfer through the tip-sample contact by the subtraction of the signal due to the heat transferred through the air.
Abstract: Although scanning thermal microscope has shown the highest spatial resolution in local temperature and thermophysical property measurement, its usefulness has been severely limited due to difficulties in quantitative measurement. We propose a double scan technique that measures temperature only from the heat transfer through the tip-sample contact by the subtraction of the signal due to the heat transfer through the air. A rigorous theoretical model for this technique is derived. The effectiveness of the double scan technique in quantitative temperature measurement is demonstrated experimentally.
69 citations
TL;DR: A finite element technique for analysis of adhesive contact is developed in which the adhesive force is modeled as a body force derived from Lennard-Jones 12-6 potential Adhesive contact of an elastic hemispherical asperity with the plane surface of a semi-infinite rigid body is analyzed Variations of the interaction force and contact radius during approach and withdrawal, and the dependence of pull-off force on the as perity radius are shown to be in good agreement with those of Maugis-Dugdale model.
58 citations
TL;DR: In this article, the authors present the 2ω method, a novel ac mode local thermal property imaging technique with nanoscale spatial resolution, which can extract thermoelectric signals from a thermocouple junction while electrically heating it simultaneously.
Abstract: In this and the following companion articles, the authors present the 2ω method, a novel ac mode local thermal property imaging technique with nanoscale spatial resolution. To demonstrate the use of the thermoelectric probe as an active one that can function as both a heater and a temperature sensor, the authors develop and implement the 2ω signal measurement technique, which can extract thermoelectric signals from a thermocouple junction while electrically heating it simultaneously. The principle of the 2ω signal measurement technique is explained by a steady periodic electrothermal analysis. The authors use a specially designed test pattern to experimentally verify that the 2ω signal is caused by the temperature oscillation induced by Joule heating. In addition, based on the results from an experiment using a cross-shaped pattern, the measurement accuracy of the 2ω method depends on the junction size of the thermoelectric probe. The 2ω method is implemented and compared with other methods in the followi...
45 citations
Cited by
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University of Illinois at Urbana–Champaign1, Massachusetts Institute of Technology2, Harvard University3, Stanford University4, Rensselaer Polytechnic Institute5, Pennsylvania State University6, University of California, Berkeley7, Brown University8, University of Florida9, University of Texas at Austin10
TL;DR: In this article, a review of thermal transport at the nanoscale is presented, emphasizing developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field.
Abstract: A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ∼1 nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interface...
1,307 citations
TL;DR: In this article, a survey of recent advances and an understanding of physical mechanisms of energy transport in nanostructures focusing mainly on molecular junctions and atomic wires is presented, and basic issues such as thermal conductivity, thermoelectricity, local temperature and heating are examined.
Abstract: Advances in the fabrication and characterization of nanoscale systems now allow for a better understanding of one of the most basic issues in science and technology: the flow of heat at the microscopic level. In this Colloquium recent advances are surveyed and an understanding of physical mechanisms of energy transport in nanostructures is presented, focusing mainly on molecular junctions and atomic wires. Basic issues are examined such as thermal conductivity, thermoelectricity, local temperature and heating, and the relation between heat current density and temperature gradient---known as Fourier's law. Both theoretical and experimental progress are critically reported in each of these issues and future research opportunities in the field are discussed.
720 citations
TL;DR: This review will first discuss recent advances in computational and experimental methods used in nanoscale thermal transport studies, followed by reviews of novel thermal transport phenomena at the nanoscales observed in both computational and Experimental studies, and discussion on current understanding of these novel phenomena.
Abstract: Heat transfer can differ distinctly at the nanoscale from that at the macroscale. Recent advancement in computational and experimental techniques has enabled a large number of interesting observations and understanding of heat transfer processes at the nanoscale. In this review, we will first discuss recent advances in computational and experimental methods used in nanoscale thermal transport studies, followed by reviews of novel thermal transport phenomena at the nanoscale observed in both computational and experimental studies, and discussion on current understanding of these novel phenomena. Our perspectives on challenges and opportunities on computational and experimental methods are also presented.
234 citations
TL;DR: In this paper, a review of the main scanning probe microscopy-based techniques developed for thermal imaging with nanoscale spatial resolution is presented, which includes the characterization of operating devices, the measurements of the effective thermal conductivity of nanomaterials and local phase transition temperatures.
Abstract: Fundamental research and continued miniaturization of materials, components and systems have raised the need for the development of thermal-investigation methods enabling ultra-local measurements of surface temperature and thermo-physical properties in many areas of science and applicative fields. Scanning thermal microscopy (SThM) is a promising technique for nanometer-scale thermal measurements, imaging, and study of thermal transport phenomena. This review focuses on fundamentals and applications of SThM methods. It inventories the main scanning probe microscopy-based techniques developed for thermal imaging with nanoscale spatial resolution. It describes the approaches currently used to calibrate the SThM probes in thermometry and for thermal conductivity measurement. In many cases, the link between the nominal measured signal and the investigated parameter is not straightforward due to the complexity of the micro/nanoscale interaction between the probe and the sample. Special attention is given to this interaction that conditions the tip–sample interface temperature. Examples of applications of SThM are presented, which include the characterization of operating devices, the measurements of the effective thermal conductivity of nanomaterials and local phase transition temperatures. Finally, future challenges and opportunities for SThM are discussed.
212 citations
TL;DR: In this article, a microstructure-based fracture mechanics model is presented to investigate the toughening effect due to the crack-bridging mechanism of platelets, and some guidelines for the biomimetic design of novel materials are proposed based on their theoretical analysis.
Abstract: Studying the structure–property relation of biological materials can not only provide insight into the physical mechanisms underlying their superior properties and functions but also benefit the design and fabrication of advanced biomimetic materials. In this paper, we present a microstructure-based fracture mechanics model to investigate the toughening effect due to the crack-bridging mechanism of platelets. Our theoretical analysis demonstrates the crucial contribution of this mechanism to the high toughness of nacre. It is found that the fracture toughness of nacre exhibits distinct dependence on the sizes of platelets, and the optimized ranges for the thickness and length of platelets required to achieve higher fracture toughness are given. In addition, the effects of such factors as the mechanical properties of the organic phase (or interfaces), the effective elastic modulus of nacre, and the stacking pattern of platelets are also examined. Finally, some guidelines for the biomimetic design of novel materials are proposed based on our theoretical analysis.
211 citations