• Advances in nano research
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• 제2권1호
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• pp.15-22
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• 2014

In recent years, spins of confined carriers in quantum dots are promising candidates for the logical units in quantum computers. In many concepts developed so far, the individual spin q-bits are being manipulated by magnetic fields, which is difficult to achieve. In the current research the recent developments of spin based quantum computing has been reviewed. Then, Single-hole spin in a molecular quantum dots with less energy and more speed has been electrically manipulated and the results have been compared with the magnetic manipulating of the spin.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.40-40
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• 2010

CdSe nanocrystals (NCs) have been decorated on singlewalled carbon nanotubes (SWCNTs) by combining a method of chemically modified substrate along with gate-bias control. CdSe/ZnS core/shell quantum dots were negatively charged by adding mercaptoacetic acid (MAA). The silicon oxide substrate was decorated by octadecyltrichlorosilane (OTS) and converted to hydrophobic surface. The negatively charged CdSe NCs were adsorbed on the SWCNT surface by applying the negative gate bias. The selective adsorption of CdSe quantum dots on SWCNTs was confirmed by confocal laser scanning microscope. The measured photocurrent clearly demonstrates that CdSe NCs decorated SWCNT can be used for photodetector and solar cell that are operable over a wide range of wavelengths.

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권3호
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• pp.131-135
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• 2006

High electron mobility transistors with InAs channels and antimonide barriers were grown on Si and GaAs substrates by means of molecular beam epitaxy. While direct growth of Sb materials on Si substrate generates disordered and coalescences 3-D growth, smooth and mirror-like 2D growth can be repeatedly obtained by inserting AlSb QD layers between them. Room-temperature electron mobilities of over 10,000 $cm^2/V-s$ and 20,000 $cm^2/v-s$ can be routinely obtained on Si and GaAs substrates, respectively, after optimizing the buffer structure as well as maintaining InSb-like interface.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.208-211
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• 1997

We have fabricated a single-electron-tunneling(SET) transistor with a dual gate geometry based on the SOI structure prepared by SIMOX wafers. The split-gate is the lower-gate is the lower-level gate and located ∼ 100${\AA}$ right above the inversion layer 2DEG active channel, which yields strong carrier confinement with fully controllable tunneling potential barrier. The transistor is operating at low temperatures and exhibits the single electron tunneling behavior through nano-size quantum dot. The Coulomb-Blockade oscillation is demonstrated at 15mK and its periodicity of 16.4mV in the upper-gate voltage corresponds to the formation of quantum dots with a capacity of 9.7aF. For non-linear transport regime, Coulomb-staircases are clearly observed up to four current steps in the range of 100mV drain-source bias. The I-V characteristics near the zero-bias displays typical Coulomb-gap due to one-electron charging effect.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2312-2314
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• 2005

For the upcoming nano-bio technology(NBT), we suggested InAs self-assembled quantum dot enhanced resonant-cavity avalanche type photodetector to detect near infrared(NIR) wavelength. To confirm the feasibility of RC-APD structure, we have simulated using conventional simulator.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.330-333
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• 2005

The fabrication of mold fur nano imprint lithography (NIL) is experimentally reported using the scanning probe lithography (SPL) technique, instead of the conventional I-beam lithography technique. The nanometer scale patterning structure is fabricated by the localized generation of oxide patterning on the silicon (100) wafer surface with a thin oxide layer, The fabrication method is based on the contact mode of scanning probe microscope (SPM) in air, The precision cleaning process is also performed to reach the low roughness value of $R_{rms}=0.084 nm$, which is important to increase the reproducibility of patterning. The height and width of the oxide dot are generated to be 15.667 nm and 209.5 nm, respectively, by applying 17 V during 350 ms.

• 한국항공우주학회지
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• 제34권5호
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• pp.65-73
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• 2006

위성이 발사체로부터 분리될 때 초기 각속도가 발생한다. B-dot 로직은 일반적으로 위성의 초기각속도 제어에 사용되나, 상대적으로 제어시간이 많이 소요된다는 단점이 있다. 이런 문제를 해결하기 위해 본 논문에서는 피치 바이어스 모멘텀 방식을 사용하는 초소형 위성에 적용 가능한 디텀블링(detumbling) 방식을 새롭게 제안하였다. 제안된 디텀블링 방식은 제어시간이 약 20분 이내로 기존의 방식에 비해 상당한 시간을 줄일 수 있다. 본 논문에서 제안한 디텀블링 방식을 사용할 경우 기존의 모멘텀 휠 초기구동 방식을 사용할 수 없다. 따라서 휠의 속도를 안정적으로 공칭 속도까지 증가시키는 방식을 제안하고 시뮬레이션을 통해 비교, 검증하였다. 시뮬레이션 결과 기존의 방식과 비교했을 때 제어시간을 단축할 수 있었으며 휠의 공칭 속도와 3축 안정화를 이룰 수 있었다.

• 한국진공학회지
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• 제15권3호
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• pp.308-313
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• 2006

서로 다른 성장조건 하에서 자발형성 InAs 양자점 (quantum dot, QD)을 제작하고. 그 특성을 photoluminescence (PL) 로 분석하였다. 비교적 높은 기판온도에서 성장된 QD 시료들의 PL 스펙트럼에서 분명한 차이를 나타내는 double-peak이 관측되었다. 온도 및 여기광 출력의존성 (temperature- and excitation power dependence) PL을 이용하여 그 double-peak이 서로 다른 크기분포를 가지는 두개의 InAs QD집단에서의 기저발광 (Eo) 에 의한 peak 임을 알 수 있었다. 게다가 이중크기분포에서 InAs 두께변화는 서로 대립되는 두 QD집단에서 QD 수의 변화를 초래한다는 것 또한 증명하였다.

• Advances in nano research
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• 제15권6호
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• pp.521-531
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• 2023

Quantum-dot cellular automata (QCA) has shown great potential in the nanoscale regime as a replacement for CMOS technology. This work presents a specific approach to static random-access memory (SRAM) cell based on 2:1 multiplexer, 4-bit SRAM array, and 32-bit SRAM array in QCA. By utilizing the proposed SRAM array, a single-layer 16×32-bit SRAM with the read/write capability is presented using an optimized signal distribution network (SDN) crossover technique. In the present study, an extremely-optimized 2:1 multiplexer is proposed, which is used to implement an extremely-optimized SRAM cell. The results of simulation show the superiority of the proposed 2:1 multiplexer and SRAM cell. This study also provides a more efficient and accurate method for calculating QCA costs. The proposed extremely-optimized SRAM cell and SRAM arrays are advantageous in terms of complexity, delay, area, and QCA cost parameters in comparison with previous designs in QCA, CMOS, and FinFET technologies. Moreover, compared to previous designs in QCA and FinFET technologies, the proposed structure saves total energy consisting of overall energy consumption, switching energy dissipation, and leakage energy dissipation. The energy and structural analyses of the proposed scheme are performed in QCAPro and QCADesigner 2.0.3 tools. According to the simulation results and comparison with previous high-quality studies based on QCA and FinFET design approaches, the proposed SRAM reduces the overall energy consumption by 25%, occupies 33% smaller area, and requires 15% fewer cells. Moreover, the QCA cost is reduced by 35% compared to outstanding designs in the literature.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.77-77
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• 2016

Thin films synthesized by plasma processes have been widely applied in a variety of industrial sectors. The structure control of thin film is one of prime factor in most of these applications. It is well known that the structure of this film is closely associated with plasma parameters and species of plasma which are electrons, ions, radical and neutrals in plasma processes. However the precise control of structure by plasma process is still limited due to inherent complexity, reproducibility and control problems in practical implementation of plasma processing. Therefore the study on the fundamental physical properties that govern the plasmas becomes more crucial for molecular scale control of film structure and corresponding properties for new generation nano scale film materials development and application. The thin films are formed through nucleation and growth stages during thin film depostion. Such stages involve adsorption, surface diffusion, chemical binding and other atomic processes at surfaces. This requires identification, determination and quantification of the surface activity of the species in the plasma. Specifically, the ions and neutrals have kinetic energies ranging from ~ thermal up to tens of eV, which are generated by electron impact of the polyatomic precursor, gas phase reaction, and interactions with the substrate and reactor walls. The present work highlights these aspects for the controlled and low-temperature plasma enhanced chemical vapour disposition (PECVD) of Si-based films like crystalline Si (c-Si), Si-quantum dot, and sputtered crystalline C by the design and control of radicals, plasmas and the deposition energy. Additionally, there is growing demand on the low-temperature deposition process with low hydrogen content by PECVD. The deposition temperature can be reduced significantly by utilizing alternative plasma concepts to lower the reaction activation energy. Evolution in this area continues and has recently produced solutions by increasing the plasma excitation frequency from radio frequency to ultra high frequency (UHF) and in the range of microwave. In this sense, the necessity of dedicated experimental studies, diagnostics and computer modelling of process plasmas to quantify the effect of the unique chemistry and structure of the growing film by radical and plasma control is realized. Different low-temperature PECVD processes using RF, UHF, and RF/UHF hybrid plasmas along with magnetron sputtering plasmas are investigated using numerous diagnostics and film analysis tools. The broad outlook of this work also outlines some of the 'Grand Scientific Challenges' to which significant contributions from plasma nanoscience-related research can be foreseen.