Young-Jun Yu

Publications (6)7.69 Total impact

• Article: Near-field optical study of highly dense laterally coupled InAs single quantum dots

  Young-Jun Yu, Haneol Noh, Gun Sang Jeon, Heung-Ryoul Noh, Yasuhiko Arakawa, Wonho Jhe
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  ABSTRACT: The authors report on high-resolution photoluminescence (PL) spectroscopy and microscopy study of laterally coupled, self-assembled InAs/GaAs quantum dots (QDs) by using the low-temperature near-field scanning optical microscope. In particular, they have observed characteristic doublet PL spectra, which can be indirectly but unambiguously attributed to two neighboring coupled QDs, as indicated by the identical spatial images of the PL intensity. This work may open a unique and systematic way to study the lateral coupling of single QDs for qualitative nano-optical analysis and characterization.
  Applied Physics Letters 07/2007; 91(4):041117-041117-3. · 3.84 Impact Factor
• Source

  Available from: arxiv.org

  Article: Near-field Optical Spectroscopy and Microscopy of Laterally Coupled Quantum Dots: Bonding and Antibonding States

  Young-Jun Yu, Haneol Noh, Gun Sang Jeon, Yasuhiko Arakawa, Wonho Jhe
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  ABSTRACT: We report on high-resolution photoluminescence (PL) spectroscopic and microscopic study of laterally coupled InAs/GaAs self-assembled quantum dots by using a low-temperature near-field scanning optical microscope. We have observed slightly split PL spectra, which are associated with the bonding (symmetric) and antibonding (antisymmetric) energy states between two coupled quantum dots, closely located each other as confirmed by spatial mapping of the PL intensity. The experimental results are in qualitative agreement with the simple theoretical calculations based on a two-dimensional potential model. This work may open the way to a simultaneous spectroscopy and microscopy study of laterally coupled quantum dots in a high-density quantum dot sample without any articulate sample fabrication.
  07/2006;
• Source

  Available from: arxiv.org

  Article: Near-field spectroscopy of bimodal size distribution of InAs/AlGaAs quantum dots

  Young-Jun Yu, I. T. Jeong, J. C. Woo, Wonho Jhe
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  ABSTRACT: We report on high-resolution photoluminescence (PL) spectroscopy of spatial structure of InAs/AlGaAs quantum dots (QDs) by using a near-field scanning optical microscope (NSOM). The double-peaked distribution of PL spectra is clearly observed, which is associated with the bimodal size distribution of single QDs. In particular, the size difference of single QDs, represented by the doublet spectral distribution, can be directly observed by the NSOM images of PL. Comment: 3pages, 3figues
  04/2005;
• Source

  Available from: arxiv.org

  Article: Near-field photoluminescence study of InAs/AlGaAs quantum-dot-based nanoclusters: band filling effect

  Young-Jun Yu, Han-Eol Noh, Mun-Heon Hong, I. T. Jeong, J. C. Woo, Yeonsang Park, Heonsu Jeon, Wonho Jhe
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  ABSTRACT: We have performed near-field spectroscopy and microscopy of the InAs/AlGaAs quantum-dot-based nanoclusters. It is observed that the photoluminescence spectra of spatially confined excitons in the nanoclusters is blue-shifted up to 20 meV as the power density is increased. In particular, the near-field photoluminescence images have shown that excitons became spatially confined gradually from lower energy state (1.4150 eV) to higher energy state (1.4392 eV) as the excitation power is increased, which is indicative of the band-filling effect of semiconductor nanostructures. Comment: 3pages, 5 figures
  03/2005;
• Article: High-resolution near-field spectroscopy of InAs single quantum dots at 70 K

  Young-Jun Yu, Wonho Jhe, Yasuhiko Arakawa
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  ABSTRACT: We have performed high-resolution near-field laser spectroscopy and microscopy of single InAs/GaAs quantum dots near liquid nitrogen temperature. By simultaneous use of 100-nm shadow mask apertures and a 30-nm-aperture fiber probe, we have achieved photoluminescence (PL) resolution comparable to that available at liquid helium temperature. In particular, we have obtained a PL linewidth of 0.6 meV for single exciton states, and observed biexciton states with quadratic power dependence. © 2003 American Institute of Physics.
  Applied Physics Letters 10/2003; 83(15):3024-3026. · 3.84 Impact Factor
• Article: Focusing characteristics of optical fiber axicon microlens for near-field spectroscopy: Dependence of tip apex angle

  Young-Jun Yu, Haneol Noh, Mun-Heon Hong, Heung-Ryoul Noh, Yasuhiko Arakawa, Wonho Jhe
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  ABSTRACT: We fabricated axicon microlenses on a single-mode bare optical fiber by using selective chemical etching technique. By varying the concentration and mixture ratios of etching solutions, we could make axicon microlenses with different apex angles (118°, 107° and 90°). We measured the illumination and collection efficiency of these microlenses by both objective-lens imaging and near-field photoluminescence (PL) spectroscopy of semiconductor quantum dots with respect to the distance between the sample and the axicon lens probe. We found that axicons with 118° and 107° [90°] apex angle tend to exhibit the laser focusing spot sizes of about 406 and 478 nm [382 nm] and maintain the high [slightly low] collection PL intensity with the distance between the sample and the axicon probe.
  Optics Communications.