• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.53-55
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• 1986

The $trans{\rightarrow}cis$ photoisomerization and fluorescence of trans-1,2-bispyrazylethylene were investigated in various conditions. The quantum yields of the $trans{\rightarrow}cis$ photoisomerization and the fluorescence intensity of trans-1,2-bispyrazylethylene decrease on going from neutral to acidic or basic solutions. The quantum yields of photoisomerization, however, are little affected by changing the concentration of salt while the fluorescence intensity increases as the concentration of salt increases. pH and salt effects on the energy levels of $^1(n,\;{\pi}^*)\;and\;^1({\pi},\; {\pi}^*)$ states lead to opposing changes in photoisomerization and fluorescence quantum yields. The heavy atom effect on the fluorescence of 1,2-bispyrazylethylene was also investigated.

• ETRI Journal
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• v.36 no.1
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• pp.89-98
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• 2014

The integration of digital circuits has a tight relation with the scaling down of silicon technology. The continuous scaling down of the feature size of CMOS devices enters the nanoscale, which results in such destructive effects as short channel effects. Consequently, efforts to replace silicon technology with efficient substitutes have been made. The carbon nanotube field-effect transistor (CNTFET) is one of the most promising replacements for this purpose because of its essential characteristics. Various digital CNTFET-based circuits, such as standard logic cells, have been designed and the results demonstrate improvements in the delay and energy consumption of these circuits. In this paper, a new CNTFET-based 5-input XOR gate based on a novel design method is proposed and simulated using the HSPICE tool based on the compact SPICE model for the CNTFET at the 32-nm technology node. The proposed method leads to improvements in performance and device count compared to the conventional CMOS-style design.

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.953-958
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• 2007

Anchoring quantum dots (QDs) onto thermodynamically stable, large band gap oxide semiconductors is a very important strategy to enhance their quantum yields for solar energy conversion in both visible and near-IR regions. We describe a general procedure for anchoring a few chalcogenide QDs onto the titanium oxide layer. To anchor the colloidal QDs onto a mesoporous TiO2 layer, linker molecules containing both carboxylate and thiol functional groups were initially attached to TiO2 layers and subsequently used to capture dispersed QDs with the thiol group. Employing the procedure, we exploited cadmium selenide (CdSe) and cadmium telluride (CdTe) quantum dots (QDs) as inorganic sensitizers for a large band gap TiO2 layer of dye-sensitized solar cells (DSSCs). Their attachment was confirmed by naked eyes, absorption spectra, and photovoltaic effects. A few QD-TiO2 systems thus obtained have been characterized for photoelectrochemical solar energy conversion.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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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.

• Current Optics and Photonics
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• v.4 no.6
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• pp.509-515
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• 2020

A practical single photon source for fiber-based quantum information processing is still lacking. As a possible 1.55-㎛ quantum-dot single photon source, an InGaAsP/InP-air-aperture micropillar cavity is investigated in terms of fabrication tolerance. By properly modeling the processing uncertainty in layer thickness, layer diameter, surface roughness and the cavity shape distortion, the fabrication imperfection effects on the cavity quality are simulated using a finite-difference time-domain method. It turns out that, the cavity quality is not significantly changing with the processing precision, indicating the robustness against the imperfection of the fabrication processing. Under thickness error of ±2 nm, diameter uncertainty of ±2%, surface roughness of ±2.5 nm, and sidewall inclination of 0.5°, which are all readily available in current material and device fabrication techniques, the cavity quality remains good enough to form highly efficient and coherent 1.55-㎛ single photon sources. It is thus implied that a quantum dot contained InGaAsP/InP-air-aperture micropillar cavity is prospectively a practical candidate for single photon sources applied in a fiber-based quantum information network.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.12
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• pp.1027-1031
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• 2001

A new constant growth technique to conserve an initial grating height of V-groove AlGaAs/InGaAs quantum nanostructures above 1.0 $\mu\textrm{m}$ thickness has been successfully embodied on submicron gratings using low pressure metalorganic chemical vapor deposition. A GaAs buffer prior to an AlGaAs barrier layer on submicron gratings plays an important role in overcoming mass transport effects and improving the uniformity of gratings. Transmission electron microscopy (TEM) image shows that high-density V-groove InGaAs quantum wires (QWRs) are well confined at the bottom of gratings. The photoluminescence (PL) peak of the InGaAs QWRs is observed in the temperature range from 10 to 280 K with a relatively narrow full width at half maximum less than 40 meV at room temperature PL. The constant growth technique is an important step to realize complex optoelectronic devices such as one-step grown distributed feedback lasers and two-dimensional photonic crystal.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.9
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• pp.397-407
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• 2002

A new simulator which predicts the quantum effect in NMOSFET structure is developed. Using the self-consistent method by numerical method, this simulator accurately predicts the carrier distribution due to improved calculation precision of potential in the inversion layer. However, previous simulator uses analytical potential distribution or analytic function based fitting parameter Using the developed simulator, threshold voltage increment and gate capacitance reduction due to the quantum effect are analyzed in NMOS. Especially, as oxide thickness and channel doping dependence of quantum effect is analyzed, and the property analysis for the next generation device is carried out.

• Journal of The Korean Association of Information Education
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• v.20 no.5
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• pp.507-518
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• 2016

In this paper, in order to offer the opportunity to indirectly experience STEAM education and the profession of a quantum computer professional, one of computer experts as a promising occupation of the future, its correlation to the national curriculum was analyzed. STEAM educational program in this paper was developed through which the third or fourth graders in elementary schools can learn about a quantum computer expert and think about it in relevance to their future careers. Yet, it's almost impossible for the students to understand the basic theories of quantum computer based on quantum mechanics, one of most difficult areas of physics. Accordingly, in this proposed textbook, gamification mechanism was applied to arouse students' interest. Moreover, the textbook was developed and applied to the field directly in the way that students would be able to indirectly experience quantum spin, one of most basic principles of quantum computer, quantum cryptography related to quantum computer, incomplete quantum computer and etc. The STEAM educational program for future careers offered in this research is expected to create positive effects for students to explore careers relevant to IT, and to develop related qualities.

• Journal of the Semiconductor & Display Technology
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• v.19 no.3
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• pp.82-87
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• 2020

The comprehensive and physics-based compact noise models for advanced CMOS devices were presented. The models incorporate important physical effects in nanoscale MOSFETs, such as the low frequency correlation effect between the drain and the gate, the trap-related phenomena, and QM (quantum mechanical) effects in the inversion layer. The drain current noise model was improved by including the tunneling assisted-thermally activated process, the realistic trap distribution, the parasitic resistance, and mobility degradation. The expression of correlation coefficient was analytically described, enabling the overall noise performance to be evaluated. With the consideration of QM effects, the comprehensive low frequency noise performance was simulated over the entire bias range.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.1
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• pp.9-15
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• 2022

Anti-cancer and therapeutic effects using therapeutic radioisotopes have been demonstrated by various studies, and it is well-known that therapeutic radioisotopes are useful in cancer treatment. Recently, one of the therapeutic radioisotopes, scandium is emerging as a radioisotope applicable to PET imaging (⁴³Sc, ⁴⁴Sc) and therapy (⁴⁷Sc) in cancer theranostic approach. However, ⁴⁷Sc has little known radiobiological and therapeutic efficacy compared to other therapeutic radioisotopes. Here, we investigated the quality and therapeutic efficacy of ⁴⁷Sc radioisotope produced by our production/isolation technology at the research reactor 'HANARO' in KAERI (Korea Atomic Energy Research Institute). We showed that the therapeutic efficacy of ⁴⁷Sc, produced by our production/isolation technology, effectively suppressed epidermal growth factor receptor (EGFR)-targeted non-small cell lung cancer (NSCLC) cells. Consequently, these results suggest that the high quality of the produced ⁴⁷Sc by our production/isolation technology enables the development of therapeutic strategies for cancer treatment and radiopharmaceuticals using ⁴⁷Sc.