• Title/Summary/Keyword: Quantum dot

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Quenched Fano effect due to one Majorana zero mode coupled to the Fano interferometer

  • Wang, Qi;Zhu, Yu-Lian
    • Current Applied Physics
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    • v.18 no.11
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    • pp.1275-1279
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    • 2018
  • We investigate the change of the Fano effect by considering one Majorana zero mode to couple laterally to the single-dot Fano interferometer. It is found that the Majorana zero mode quenches the Fano effect thoroughly and causes the conductance to be independent of the dot level, the dot-lead coupling, and the increase of the Majorana-dot coupling. As a result, the linear conductance becomes only related to the interlead coupling and the magnetic-flux phase factor. These results can be helpful for the detection of Majorana zero mode.

Optical Characteristic of InAs Quantum Dots in an InGaAs/GaAs Well Structure (광학적 방법으로 측정된 양자우물 안의 InAs 양자점의 에너지 준위)

  • Nam H.D.;Kwack H.S.;Doynnette L.;Song J.D.;Choi W.J.;Cho W.J.;Lee J.I.;Cho Y.H.;Julien F.H.;Choe J.W.;Yang H.S.
    • Journal of the Korean Vacuum Society
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    • v.15 no.2
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    • pp.209-215
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    • 2006
  • We investigated the optical property and the electronic subband structure of InAs quantum dots in an InAsGa/GaAs well structure utilizing photoluminescence (PL), PL excitation (PLE) and near infrared transmission spectroscopy. From transmission and PLE spectra, we found three bound states in the InAs quantum dot and two bound states in InGaAs/GaAs quantum well, and correlated to the results of intersubband transitions observed in photocurrent spectrum.

Improved charge balance in quantum dot light-emitting diodes using self-assembled monolayer (자기조립단분자막을 이용한 양자점 발광다이오드의 전하 균형도 개선)

  • Sangwook Park;Woon Ho Jung;Yeyun Bae;Jaehoon Lim;Jeongkyun Roh
    • Journal of IKEEE
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    • v.27 no.1
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    • pp.30-37
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    • 2023
  • To improve the efficiency and stability of colloidal quantum dot light-emitting diodes (QD-LEDs), it is essential to achieve charge balance within the QD emissive layer. Zinc oxide (ZnO) is widely used for constructing an electron transport layer in the state-of-the-art QD-LEDs, but spontaneous electron injection from ZnO often results in excessive electrons in QDs that significantly deteriorate the performance of QD-LEDs. In this study, we demonstrated the improved performance of QD-LEDs by modifying the electron injection property of ZnO with self-assembled monolayer (SAM)-treatment. As a result of improved charge balance, the external quantum efficiency and maximum luminance of QD-LEDs with SAM-treatment were improved by 25% and 200%, respectively, compared to the devices without SAM-treatment.

Anchoring Cadmium Chalcogenide Quantum Dots (QDs) onto Stable Oxide Semiconductors for QD Sensitized Solar Cells

  • Lee, Hyo-Joong;Kim, Dae-Young;Yoo, Jung-Suk;Bang, Ji-Won;Kim, Sung-Jee;Park, Su-Moon
    • 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.

Design of Extendable BCD-EXCESS 3 Code Convertor Using Quantum-Dot Cellular Automata (확장성을 고려한 QCA BCD-3초과 코드 변환기 설계)

  • You, Young-won;Jeon, Jun-cheol
    • Journal of Advanced Navigation Technology
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    • v.20 no.1
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    • pp.65-71
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    • 2016
  • Quantum-dot cellular automata (QCA) consists of nano-scale cells and demands very low power consumption so that it is one of the alternative technologies that can overcome the limits of scaling CMOS technologies. Typical BCD-EXCESS 3 code converters using QCA have not considered the scalability so that the architectures are not suitable for a large scale circuit design. Thus, we design a BCD-EXCESS 3 code converter with scalability using QCADesigner and verify the effectiveness by simulation. Our structure have reduced 32 gates and 7% of garbage space rate compare with typical URG BCD-EXCESS 3 code converter. Also, 1 clock is only needed for circuit expansion of our structure though typical QCA BCD-EXCESS 3 code converter demands 7 clocks.

Application of Quantum-dot Nanocrystals for Cyanobacterial Toxin-Microcystin Detection (나노크리스탈 Quantum-dot을 적용한 남조류 독소 Microcystin 탐지 연구)

  • Lee, Jinwook;Yu, Hye-Weon;Kim, In S.
    • Journal of Korean Society on Water Environment
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    • v.23 no.5
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    • pp.705-711
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    • 2007
  • Green quantum-dot nanocrystal (QD525) with anti-microcystin monoclonal antibody was applied for detection of microcystin, a monocyclic peptide hepatotoxin, extracted from the culture of Microcystis aeruginosa. The presence of microcystin in the cell lysate was verified by HPLC analysis with UV absorbance at 238 nm. Microcystis cell extract exhibited fluorescence emission spectra, which peak was around 460 nm because of their complex organic substances. When a spherical QD525 antibody conjugates (10~20 nm in diameter) were bound to the microcystins in the Microcystis cell lysate, the fluorescence intensity of the primary peak at 525 nm diminished while the secondary emission peak at 460 nm slightly increased intensities. It is due to energy transfer from the primary (major) to the secondary (minor) peak, resulting from physical deformation of QD525 and different environmental factors. On the other hand, other cell extracts did not show any fluorescence emission change. This study is very available for detecting and monitoring the microcystin because it is one step assay without washing step and portable spectrophotometer makes on-site measurement possible. For health risk assessment of the microcystin, the reliable and rapid system to detect and quantify microcystin is seriously required.