• Journal of the Optical Society of Korea
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• v.15 no.2
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• pp.124-127
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• 2011

Quantum dots were designed within a GRIN-SCH(Graded index - Separate confinement Heterostructure) heterostructure to create a high power InAlAs/AlGaAs laser diode. 808 nm light emission was with a quantum dot composition of In0.665Al0.335As and wetting layer composition of Al0.2Ga0.8As by LASTIP simulation software. Typical characteristics of GRIN structures such as high confinement ratios and Gaussian beam profiles were shown to still apply when quantum dots are used as the active media. With a dot density of 1.0x1011 dots/cm2, two quantum dot layers were found to be good enough for low threshold, high-power laser applications.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.01a
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• pp.33-34
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• 2017

본 논문에서는 Kinect 센서 기반의 Connecting Dots 게임을 설계하고 구현한다. 이 게임은 유아용 게임으로 3개 스테이지로 구성되며 각 스테이지는 난이도에 따라 벨, 꽃, 사자 점선 그림으로 구성한다. 각 스테이지에서는 그림 내의 점선을 연결하여 하나의 그림을 완성한다. 각 스테이지 마다 그림 하단에 힌트로 영어 단어가 제시되어 사용자가 그 힌트를 이용하여 그림을 유추 할 수 있다. 또한, Kinect 센서로 얻은 플레이어의 스켈레톤 정보와 점선 좌표를을 이용하여 플레이어를 연동시킨다.

• Applied Science and Convergence Technology
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• v.25 no.1
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• pp.1-6
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• 2016

Quantum dots (QDs) are considered as excellent color conversion and self-emitting materials for display and lighting applications. In this article, various technologies which can be used to realize white light emission with QDs are discussed. QDs have good color purity with a narrow emission spectrum and tunable optical properties with size control capabilities. For white light emission with a color-conversion approach, QDs are combined with blue-emitting inorganic and organic light-emitting diodes (LED) to generate white emission with high energy conversion efficiency and a high color rendering index for various display and lighting applications. Various device structures for self-emitting white QD light-emitting diodes (QD-LED) are also reviewed. Various stacking and patterning technologies are discussed in relation to QD-LED devices.

• Korean Journal of Cognitive Science
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• v.12 no.4
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• pp.49-56
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• 2001

When multiple features are presented in the image the computational models for stereopsis select the most activated matches through the excitatory and inhibitory interactions among all possible matches. Using the random-dot stereogram with two surfaces. we investigate whether human binocular mechanism selects the most activated matches. The dots consisting a surface lying in a fixation plane were selected randomly while each of the dots consisting the other surface was paired with each of the original dots in the following manner. After finding the position of each dots in the original random pattern we placed an additional dot to the left and to the right of the original position in each of the left and right image of a stereogram respectively. The luminance of additional dots was varied while that of the original random dots was fixed so that the hypothetical matches presumably could be activated differently. Across the luminance condition the depth of each surface was measured to examine whether matches to be selected were changed depending on the activation level of possible matches. When the luminance of two patterns was within 30% of one another observers perceived an opaque surface. Beyond this value two transparent surfaces were seen with the magnitude of perceived depth varying with relative luminance of two patterns. When original pattern was brighter one additional surface was perceived at the depth corresponding to the disparity of original pattern. When original dot was dimmer. however the depth of an additional surface corresponded to the disparity of newly introduced pattern. These results suggest that there are dynamic interactions within the matching process whereby highly activated matches inhibit weaker one.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.606-610
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• 2010

Films consisting of a silicon quantum dot superlattice were fabricated by alternating deposition of silicon rich silicon nitride and $Si_3N_4$ layers using an rf magnetron co-sputtering system. In order to use the silicon quantum dot super lattice structure for third generation multi junction solar cell applications, it is important to control the dot size. Moreover, silicon quantum dots have to be in a regularly spaced array in the dielectric matrix material for in order to allow for effective carrier transport. In this study, therefore, we fabricated silicon quantum dot superlattice films under various conditions and investigated crystallization behavior of the silicon quantum dot super lattice structure. Fourier transform infrared spectroscopy (FTIR) spectra showed an increased intensity of the $840\;cm^{-1}$ peak with increasing annealing temperature due to the increase in the number of Si-N bonds. A more conspicuous characteristic of this process is the increased intensity of the $1100\;cm^{-1}$ peak. This peak was attributed to annealing induced reordering in the films that led to increased Si-$N_4$ bonding. X-ray photoelectron spectroscopy (XPS) analysis showed that peak position was shifted to higher bonding energy as silicon 2p bonding energy changed. This transition is related to the formation of silicon quantum dots. Transmission electron microscopy (TEM) and electron spin resonance (ESR) analysis also confirmed the formation of silicon quantum dots. This study revealed that post annealing at $1100^{\circ}C$ for at least one hour is necessary to precipitate the silicon quantum dots in the $SiN_x$ matrix.

• Korean Journal of Optics and Photonics
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• v.17 no.3
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• pp.278-284
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• 2006

We have fabricated and measured electrooptic modulator using coupled stack InAs/InGaAs quantum dots. The height of the quantum dot is 16 nm and quantum dots are stacked including an InGaAs capping layer. The peak wavelength of photoluminescence is 1260 nm at room temperature and 1158 nm at 12 K. The operation characteristics of the quantum dots show high modulation efficiency of electrooptic modulator at 1550 nm compared to that of existing III-V bulk and MQW type semiconductor. The measured switching voltage ($V\pi$) is 540 and 600 mV, for TE mode and TM mode, respectively. From the results, the modulation efficiency can be determined as 333.3 and $300^{\circ}/V{\cdot}mm$ for TE and TM modes. The results reported here may lead to the design and fabrication of a novel electrooptic modulator with low switching voltage and high efficiency.

• Journal of the Optical Society of Korea
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• v.10 no.4
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• pp.184-187
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• 2006

For resonant excitation of the ground state $1s^e-1S^h_{3/2}$, dynamics of 'the electron-hole pair in a CdSe quantum dot was investigated by degenerate pump-probe measurement. At low e-h pair densities, the decay of $1s^e-1S^h_{3/2}$ state is dominated by radiative recombination. As the number of the electron-hole pairs increases, new decay features become significant. Theoretical comparison suggests this is attributed to the bi-molecular and Auger-type scattering.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.360-361
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• 2004

An atomization doping process is proposed to manufacture nonlinear optical fiber containing higher concentration of PbTe nano-particles in the core of the fiber than that by the conventional solution doping process. The absorption peaks appeared near 725nm, 880nm, and 1050nm are attributed to the PbTe quantum dots in the fiber core.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.251-252
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• 2008

We fabricated silica glass optical fiber containing PbSe quantum-dots (QD) of average size 3.2 nm. The response time of the PbSe-QD doped optical fiber was measured to be around 200 ps. However, after exposure to 1064 nm laser emission for 15 minutes, the response time dramatically reduced to around 2.5 ps, which may be due to photo-darkening effect.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.186-187
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• 2002

Recently, there has been much interest in magnetic thin film patterned in submicron scale because of possible ultrahigh density storage media or logical device applications [1-3]. Various geometries such as rectangle, circle, ring and ellipse type dots have been studied to find the shape showing stable switching behavior from repeated cycles. However, rectangle and circle types may not be suitable for device applications because they have two uncontrollable different magnetization reversal modes: C state and S state, resulting in different coercivity and irreproducible switching[4]. (omitted)