• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
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• pp.389-390
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• 2018

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.292-295
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• 2015

The effect of Ligand Binding energy in quantum rod (CdS/ZnS) plays a critical role in anisotropic growth. As mimicking large chain of ligands and using the head of the chain, I plan to bind the quantum rod and ligands so that it can grow well consequently. So the ultimate goal of this study is on how ligand binding can affect the growth of this quantum rod. There are preferred surfaces between the quantum rod and ligands, and we empirically know that ligands which bind the quantum rod; Phosphoric oxide (PO), Phosphoric acid(PA), Carboxylic acid(CA), Trimethylamine(TMA), have strong tendency to be attached on the surfaces of CdS/ZnS; ($11{\bar{2}}0$), ($10{\bar{1}}0$), ($000{\bar{1}}$), (0001). I virtually bond the surface and the ligands, and calculated the ligand binding energy after optimizing their structure, utilizing EDISON simulator. After all, I figured out how they are linked each other and how the quantum rod grows.

• Carbon letters
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• 제21권
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• pp.8-15
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• 2017

The thermoelectric Seebeck and Peltier effects of a single walled carbon nanotube (SWCNT) quantum dot nanodevice are investigated, taking into consideration a certain value of applied tensile strain and induced ac-field with frequency in the terahertz (THz) range. This device is modeled as a SWCNT quantum dot connected to metallic leads. These two metallic leads operate as a source and a drain. In this three-terminal device, the conducting substance is the gate electrode. Another metallic gate is used to govern the electrostatics and the switching of the carbon nanotube channel. The substances at the carbon nanotube quantum dot/metal contact are controlled by the back gate. Results show that both the Seebeck and Peltier coefficients have random oscillation as a function of gate voltage in the Coulomb blockade regime for all types of SWCNT quantum dots. Also, the values of both the Seebeck and Peltier coefficients are enhanced, mainly due to the induced tensile strain. Results show that the three types of SWCNT quantum dot are good thermoelectric nanodevices for energy harvesting (Seebeck effect) and good coolers for nanoelectronic devices (Peltier effect).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.172-172
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• 2010

In the area of optoelectronic devices based on GaN and related ternary compounds, the two-dimensional system like as quantum wells (QWs) has been investigated as an effective structure for improving the light-emitting efficiency. Generally, the quantum well active regions in III-nitride light-emitting diodes grown on conventional c-plane sapphire substrates have critical problems given by the quantum confined Stark effect (QCSE) due to the effects of strong piezoelectric and spontaneous polarizations. However, the QWs grown on nonpolar templates are free from the QCSE since the polar-axis lies within the growth plane of the template. Also the unique characteristic of linear polarized light emission from nonpolar QW structures is attracting attentions because it is proper to the application of back-light units of liquid crystal display. In this study, we characterized optical properties of the a-plane InGaN/GaN QW structures by temperature-dependent photoluminescence (TDPL) measurements. From the photoluminescence (PL) spectrum measured at 300 K, green emission centered at 520 nm was observed for the QW region. Since indium incorporation on nonpolar QWs is lower than that on c-plane, this high indium-doping on a-plane InGaN QWs is not common. Therefore, the effect of high indium composition on optical properties in a-plane InGaN QWs will be extensively studied.

• 대한전자공학회논문지SD
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• 제45권10호
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• pp.15-22
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• 2008

기존의 MOSFET는 단채널 현상의 증가로 인하여 스케일링에 한계를 가지고 있다. Double-Gate MOSFET (DG-MOSFET)는 소자의 길이가 축소되면서 나타나는 단채널 현상을 효과적으로 제어하는 차세대 소자이다. DG-MOSFET으로 소자를 축소시키면 채널 길이가 10nm 이하에서 게이트 방향뿐만 아니라 소스와 드레인 방향에서도 양자 효과가 발생한다. 또한 게이트 길이가 매우 짧아지면 ballistic transport 현상이 발생한다. 따라서 본 연구에서는 2차원 양자 효과와 ballistic transport를 고려하여 DG-MOSFET의 특성을 분석하였다. 또한 단채널 효과를 줄이기 위해서 $t_{si}$와 underlap 그리고 lateral doping gradient를 이용하여 소자 구조를 최적화하였다.

• Bulletin of the Korean Chemical Society
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• 제27권8호
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• pp.1186-1188
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• 2006

In this paper a new theory is presented to treat the problem of stimulated absorption and emission of photons between energy levels from the standpoint of discrete quantum jumps. In order to implement the theory a scheme to avoid the quantum Zeno effect is proposed. Numerical simulations are performed to demonstrate that this approach does not contradict the principles of the standard wave mechanics. It is shown that with this approach one can obtain photon observation statistics as well.

• JSTS:Journal of Semiconductor Technology and Science
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• 제4권1호
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• pp.27-31
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• 2004

Models and simulations of gate tunneling current for thinoxide MOSFETs and Double-Gate SOIs are discussed. A guideline in design of leaky MOS capacitors is proposed and resonant gate tunneling current in DG SOI simulated based on quantum-mechanicalmodels. Gate tunneling current in fully-depleted, double-gate SOI MOSFETs is characterized based on quantum-mechanical principles. The simulated $I_G-V_G$ of double-gate SOI has negative differential resistance like that of the resonant tunnel diodes.

• Current Optics and Photonics
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• 제1권6호
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• pp.626-630
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• 2017

GaN-based green light-emitting diode (LED) structures suffer from low internal quantum efficiency (IQE), known as the "green gap" problem. The IQE of LED structures is expected to be improved to some extent by exploiting the Purcell effect. In this study, the Purcell effect on the IQE of green LED structures is investigated numerically using a finite-difference time-domain simulation. The Purcell factor of flip-chip LED structures is found to be more than three times as high as that of epi-up LED structures, which is attributed to the high-reflectance mirror near the active region in the flip-chip LED structures. When the unmodified IQE is 20%, the relative enhancement of IQE can be greater than 50%, without utilizing the surface-plasmon coupling effect. Based on the simulation results, the "green gap" problem of GaN-based green LEDs is expected to be mitigated significantly by optimizing flip-chip LED structures to maximize the Purcell effect.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.121-125
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• 2003

Time-resolved photoluminescence from InGaN/GaN multi-quantum well structures was investigated for two different shapes of square- and trapezoidal wells grown by metal-organic chemical vapor deposition. To compare to the conventional square well structure with a radiative recombination lifetime of 0.170 nsec, the large value of lifetime of 0.540 nsec from trapezoidal well were found at room temperature. This value is similar to the value for GaN host material indicating no confinement effect of quantum well. Furthermore, the high resolution transmission electron microscopy image provides the In clustering effect in the trapezoidal well structure.

• Journal of Korean Vacuum Science & Technology
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• 제4권1호
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• pp.11-17
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• 2000

The low temperature electron mobilities were investigated in Si/$Si_{1-x}Ge_{x}$ modulation Doped (MOD) quantum well structure with thermally grown oxide. N-type Si/$Si_{1-x}Ge_{x}$ structures were fabricated by a gas source MBE. Thermal oxidation was carried out in a dry $O_2$ atmosphere at $700^{\circ}C$ for 7 hours. Electron mobilities were measured by a Hall effect and a magnetoresistant effect at low temperatures down to 0.4 K. Pronounced Shubnikov-de Haas (SdH) oscillations were observed at a low temperature showing two dimensional electron gases (2 DEG) in a tensile strained Si quantum well. The electron sheet density ($n_{s}$) of 1.5${\times}$$10^{12}$[$cm^{-2}$] and corresponding electron mobility of 14200 [$cm^2$$V^{-1}$$s^{-1}$] were obtained at low temperature of 0.4 K from Si/$Si_{1-x}Ge_{x}$ MOD quantum well structure with thermally grown oxide.