• 한국재료학회지
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• 제28권11호
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• pp.659-662
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• 2018

We report the properties of infrared photodetectors based on two kinds of quantum dots(QDs): i) 2.0 ML InAs QDs by the Stranski-Krastanov growth mode(SK QDs) and ii) sub-monolayer QDs by $4{\times}[0.3ML/1nm\;In_{0.15}Ga_{0.85}As]$ deposition(SML QDs). The QD infrared photodetector(QDIP) structure of $n^+-n^-(QDs)-n^+$ is epitaxially grown on GaAs (100) wafers using molecular-beam epitaxy. Both the bottom and top contact GaAs layers are Si doped at $2{\times}10^{18}/cm^3$. The QD layers are grown with Si doping of $2{\times}10^{17}/cm^3$ and capped by an $In_{0.15}Ga_{0.85}As$ layer at $495^{\circ}C$. The photoluminescence peak(1.24 eV) of the SML QDIP is blue-shifted with respect to that (1.04 eV) of SK QDIPs, suggesting that the electron ground state of SML QDIP is higher than that of the SK QDIP. As a result, the photoresponse regime(${\sim}9-14{\mu}m$) of the SML QDIP is longer than that (${\sim}6-12{\mu}m$) of the SK QDIP. The dark current of the SML QDIP is two orders of magnitude smaller value than that of the SK QDIP because of the inserted $Al_{0.08}Ga_{0.92}As$ layer.

• 반도체디스플레이기술학회지
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• 제20권1호
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• pp.54-58
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• 2021

The RGO with controllable oxygen functional groups is a novel material as the active layer of resistive switching memory through a reduction process. We designed a nanoscale conductive channel induced by local oxygen ion diffusion in an Au / RGO+GQD / Al resistive switching memory structure. A strong electric field was locally generated around the Al metal channel generated in BIL, and the local formation of a direct conductive low-dimensional channel in the complex RGO graphene quantum dot region was confirmed. The resistive memory design of the complex RGO graphene quantum dot structure can be applied as an effective structure for charge transport, and it has been shown that the resistive switching mechanism based on the movement of oxygen and metal ions is a fundamental alternative to understanding and application of next-generation intelligent semiconductor systems.

• 한국분말재료학회지
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• 제19권6호
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• pp.442-445
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• 2012

The quantum dots (QD) have unique electrical and optical properties due to quantum dot confinement effect. The optical properties of QDs are decided by various synthesis conditions. In a prior QDs study, a study on the QDs size with synthesis condition such as synthesis time and temperature is being extensively researched. However, the research on QDs size with composition ratio has hitherto received scant attention. In order to evaluate the ratio dependence of CdSe crystal, synthesis ratio of Se precursor is changed from 16.7 mol%Se to 44 mol%Se. As the increasing Se ratio, the band gap was increased. This is caused by red shift of emission. We confirmed optical property of CdSe QDs with composition ratio.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.9.2-9.2
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• 2011

Ultrathin polyelectrolyte (PE) multilayer films prepared by the versatile layer-by layer (LbL) assembly method have been utilized for the preparation of light-emitting diodes, electrochromic, membrane, and drug delivery system, as well as for selective area patterning and particle surface modification because the various materials with specific properties can be inserted into the film with nano-level thickness irrespective of the size or the shape of substrate. Since the introduction of the LbL technique in 1991 by Decher and Hong, various hydrophilic materials can be inserted within LbL films through complementary interactions (i.e., electrostatic, hydrogen-bonding or covalent interaction). In this study, it is demonstrated that LbL SA multilayer films based on nucleophilic substitution reaction can allow the preparation of the highly efficient magnetic and/or optical films and nonvolatile memory devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.135.2-135.2
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• 2014

Photon conversion technology for thin film solar cells is reviewed. The high-energy photons which are hardly absorbed in solar cells can be transformed the low energy photon by the photon conversion process such as down conversion or down shift, which can improve the solar cell efficiency over the material limit. CdSe-based quantum dot materials commonly used in LED can be used as the photon conversion layer for Si thin film solar cells. The photon conversion structure of CdSe-based quantum dot for Si thin film solar cells will be presented and the pros and cons for the Si thin film solar cells integrated with the photon conversion layers will be discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.195-197
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• 2002

CdTe quantum dots(QDs) were synthesized in aqueous solution by colloidal method. Photoluminescence(PL) spectra of the synthesized CdTe QDs revealed the intensity of PL peaks was stronger as the condensation time was longer. This result was thought because annealing effect by thermal energy transferred during condensation eliminated defects which act as traps and recombination centers in CdTe particle. PL intensity has stron dependence of Te precursor concentration. It confirmed the ratio of Te ion to Cd ion added during synthesis affected the particle size and size distribution of the CdTe QDs. Finally, the synthesized CdTe QDs were identified to be cubic structured CdTe quantum dots by X-ray diffraction(XRD).

• 한국태양에너지학회 논문집
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• 제39권1호
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• pp.1-9
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• 2019

Light induced degradation is one of the major research challenges of hydrogenated amorphous silicon related thin film silicon solar cells. Amorphous silicon shows creation of metastable defect states, originating from elevated concentration of dangling bonds during light exposure. The metastable defect states work as recombination centers, and mostly affects quality of intrinsic layer in solar cells. In this paper we present results of light induced degradation in thin film silicon solar cells and discussion on physical origin, mechanism and practical solutions of light induced degradation in thin film silicon solar cells. In-situ light-soaking IV measurement techniques are presented. We also present thin film silicon material with silicon nano-quantum dots embedded within amorphous matrix, which shows superior stability during light-soaking. Our results suggest that solar cell using silicon nano-quantum dots in abosrber layer shows superior stability under light soaking, compared to the conventional amorphous silicon solar cell.

• 한국재료학회지
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• 제14권2호
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• pp.146-151
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• 2004

We investigated the effects of high potential barriers on the optical characteristics of InAs quantum dots (QDs) by using photoluminescence (PL) and photoreflectance (PR) spectroscopy. A sample with regular InAs quantum dots on GaAs was grown by molecular beam epitaxy (MBE) as a reference. Another InAs QDs sample was embedded in single AlGaAs barriers. On the other hand, a sample with GaAs/AlGaAs superlattice barriers was adopted for comparison with a sample with a single AlGaAs layer. In results, we found that the emission wavelength of QDs was effectively tailored by using high potential barriers. Also, it was found that the optical properties of a sample with QDs embedded in GaAs/AlGaAs superlattices were better than those of a sample with QDs embedded in a single layer of AlGaAs barriers. We believe that GaAs/AlGaAs superlattice could effectively prevent the generation of defects.

• 벤처창업연구
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• 제7권2호
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• pp.157-165
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• 2012

프랜차이즈는 사업경험과 지식이 없어도 독자적이고 성공적인 브랜드의 상호 및 상표, 마케팅기술과 노하우의 활용, 점포 운영을 위해 필요한 경영 및 마케팅의 지원을 받아 안정적인 창업 준비와 성공적인 사업을 영위할 수 있는 하나의 창업방법이다. 이러한 프랜차이즈는 법률적으로 독립적인 두 당사자인 가맹본부와 가맹점 사업자, 생산자로 부터 소비자에게 상품 및 용역을 유통시키는 기업 활동이라는 마케팅 개념과 상품을 사람에게 전달하는 유통의 개념 측면을 포함하는 종합적인 사업방식이다. 가맹본부는 자신의 사업방법의 공급, 상표와 특허를 자신의 관리 아래 다른 사람들이 사용하도록 허용하는 법률적 존재를 말하며, 생산자가 되기도 하고, 중간도매상이 되기도 한다. 그리고 가맹점 사업자는 가맹본부나 프랜차이즈 기업과의 합의에 의해 사업을 운영하는 개인 또는 개인들로 상표나 상호를 사용하고, 상품이나 서비스를 거래 하거나 판매하며, 경영지원이나 훈련을 지원 받고, 마케팅 및 광고 지원을 받으며, 프랜차이저의 브랜드 및 인지도의 혜택을 받는다. 따라서 가맹점사업자는 프랜차이즈로부터 상호의 사용권, 제품의 판매권, 기술, 상권분석, 점포 디스플레이, 관계자 훈련 및 교육지도 등을 제공받아 소비자에게 상품이나 용역을 유통시키거나 전달하는 소매상이라고 할 수 있을 것이다. 이러한 양자 관계에서 가맹점은 가맹점 본부에 대해 불공정성을 인지하는 경우가 존재한다. 이에 대해 본 논문에서는 가맹본부의 관리적 특성이 양자관계에서의 공정성에 미치는 효과를 실증분석하고자 하였다. 가맹점본부와 가맹점과의 관계에서 본부의 관리적 특성으로서 의사소통, 메뉴개발, 보상은 모두 분배공정성과 절차공정성에 긍정적 영향을 미치는 것으로 나타났다. 이상의 연구결과를 바탕으로 다음과 같은 관리적 시사점을 제시하고자 한다. 따라서 가맹점주들로 하여금 본부에 대한 분배공정성과 절차공정성에 대한 인지도를 높이기 위해서는 본부의 가맹점에 대한 투자, 시설 및 인테리어나 비품지원, 법률적 지원, 판촉 및 교육 지원, 그리고 본부와 가맹점간의 원활한 의사소통 및 정보 공유, 다양하고도 적시의 메뉴개발, 가맹점의 서비스향상이나 고객문제해결에 따른 보상 시스템 등을 제공하는 것이 필요하다.

• 반도체디스플레이기술학회지
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• 제20권3호
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• pp.167-171
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• 2021

The core-shell InGaN/GaN Multi Quantum Well-Nanowires (MQW-NWs) that were selectively grown on oxide templates with perfectly circular hole patterns were highly crystalline and were shaped as high-aspect-ratio pyramids with semi-polar facets, indicating hexagonal symmetry. The formation of the InGaN active layer was characterized at its various locations for two types of the substrates, one containing defect-free MQW-NWs with GQDs and the other containing MQW-NWs with defects by using HRTEM. The TEM of the defect-free NW showed a typical diode behavior, much larger than that of the NW with defects, resulting in stronger EL from the former device, which holds promise for the realization of high-performance nonpolar core-shell InGaN/GaN MQW-NW substrates. These results suggest that well-defined nonpolar InGaN/GaN MQW-NWs can be utilized for the realization of high-performance LEDs.