• 제목/요약/키워드: Quantum-Mechanical Effects

검색결과 43건 처리시간 0.022초

Double Gate MOSFET Modeling Based on Adaptive Neuro-Fuzzy Inference System for Nanoscale Circuit Simulation

  • Hayati, Mohsen;Seifi, Majid;Rezaei, Abbas
    • ETRI Journal
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    • 제32권4호
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    • pp.530-539
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    • 2010
  • As the conventional silicon metal-oxide-semiconductor field-effect transistor (MOSFET) approaches its scaling limits, quantum mechanical effects are expected to become more and more important. Accurate quantum transport simulators are required to explore the essential device physics as a design aid. However, because of the complexity of the analysis, it has been necessary to simulate the quantum mechanical model with high speed and accuracy. In this paper, the modeling of double gate MOSFET based on an adaptive neuro-fuzzy inference system (ANFIS) is presented. The ANFIS model reduces the computational time while keeping the accuracy of physics-based models, like non-equilibrium Green's function formalism. Finally, we import the ANFIS model into the circuit simulator software as a subcircuit. The results show that the compact model based on ANFIS is an efficient tool for the simulation of nanoscale circuits.

고준위 도핑된 AlGaAs/GaAs 양자 우물의 충돌 이온화율 (Impact ionization rate of the highly-doped AlGaAs/GaAs quantum well)

  • 윤기정;황성범;송정근;홍창희
    • 전자공학회논문지A
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    • 제33A권4호
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    • pp.121-128
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    • 1996
  • The impact ionization rate of thethighly-doped AlGaAs/GaAs quantum well structure is calculated, which is an important parameter ot design theinfrared detector APD and the novel neural device. In conjunction with ensemble monte carlo method and quantum mechanical treatment, we analyze the effects of the parameters of quantum well structure on the impact ionization rate. Since the number of the occupied subbands increases while the energy of the subbands decreases as the width of quantum well increases, the impact ionization rate increases in the range of th esmall well width but gradually the increament slows down and is finally saturated. Due to the effect of the energy of the injected electrons into the quantum well and the tunneling through the barrier, the impact ionization rate increases for the range of the small barrier width and decreases for the range of the large barrier width. Thus, there exists a barrier width to maximize the impact ionzation rate for a mole fraction x, and the barrier width moves to the larger vaue as the mole fraction x increases. The impact ionization rate is much more sensitive to the variation of the doping density than that of the other quantum well parameters. We found that there is a limit of the doping density to confine the electronics in the quantum well effectively.

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나노-스케일 전계 효과 트랜지스터 모델링 연구 : FinFET (Modeling of Nano-scale FET(Field Effect Transistor : FinFET))

  • 김기동;권오섭;서지현;원태영
    • 대한전자공학회논문지SD
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    • 제41권6호
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    • pp.1-7
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    • 2004
  • 본 논문에서는 2차원 양자 역학적 모델링 및 시뮬레이션(quantum mechanical modeling and simulation)으로써, 자기정렬 이중게이츠 구조(self-aligned double-gate structure)인 FinFET에 관하여 결합된 푸아송-슈뢰딩거 방정식(coupled Poisson and Schrodinger equations)를 셀프-컨시스턴트(self-consistent)한 방법으로 해석하는 수치적 모델을 제안한다. 시뮬레이션은 게이트 길이(Lg)를 10에서 80nm까지, 실리콘 핀 두께($T_{fin}$)를 10에서 40nm까지 변화시켜가며 시행되었다. 시뮬레이션의 검증을 위한 전류-전압 특성을 실험 결과값과 비교하였으며, 문턱 전압 이하 기울기(subthreshold swing), 문턱 전압 롤-오프(thresholdvoltage roll-off), 그리고 드레인 유기 장벽 감소(drain induced barrier lowering, DIBL)과 같은 파라미터를 추출함으로써 단채널 효과를 줄이기 위한 소자 최적화를 시행하였다. 또한, 고전적 방법과 양자 역학적 방법의 시뮬레이션 결과를 비교함으로써,양자 역학적 해석의 필요성을 확인하였다. 본 연구를 통해서, FinFET과 같은 구조가 단채널 효과를 줄이는데 이상적이며, 나노-스케일 소자 구조를 해석함에 있어 양자 역학적 시뮬레이션이 필수적임을 알 수 있었다.

Parametric study on the structural response of a high burnup spent nuclear fuel rod under drop impact considering post-irradiated fuel conditions

  • Almomani, Belal;Kim, Seyeon;Jang, Dongchan;Lee, Sanghoon
    • Nuclear Engineering and Technology
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    • 제52권5호
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    • pp.1079-1092
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    • 2020
  • A parametric study of several parameters relevant to design safety on the spent nuclear fuel (SNF) rod response under a drop accident is presented. In the view of the complexity of interactions between the independent safety-related parameters, a factorial design of experiment is employed as an efficient method to investigate the main effects and the interactions between them. A detailed single full-length fuel rod is used with consideration of post-irradiated fuel conditions under horizontal and vertical free-drops onto an unyielding surface using finite-element analysis. Critical drop heights and critical g-loads that yield the threshold plastic strain in the cladding are numerically estimated to evaluate the fuel rod structural resistance to impact load. The combinatory effects of four uncertain parameters (pellet-cladding interfacial bonding, material properties, spacer grid stiffness, rod internal pressure) and the interactions between them on the fuel rod response are investigated. The principal finding of this research showed that the effects of above-mentioned parameters on the load-carrying capacity of fuel rod are significantly different. This study could help to prioritize the importance of data in managing and studying the structural integrity of the SNF.

중앙-채널 이중게이트 MOSFET의 양자역학적 모델링 및 시뮬레이션 연구 (Quantum-Mechanical Modeling and Simulation of Center-Channel Double-Gate MOSFET)

  • 김기동;원태영
    • 대한전자공학회논문지SD
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    • 제42권7호
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    • pp.5-12
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    • 2005
  • 본 논문에서는 결합된 슈뢰딩거-푸아송 방정식과 전류연속방정식을 셀프-컨시스턴트하게 계산함으로써, 나노-스케일 center-channel (CC) double-gate (DG) MOSFET 디바이스의 전기적 특성 및 구조해석에 관한 연구를 시행하였다. 10-80 nm 게이트 길이의 조건에서 수행한 CC-NMOS의 시뮬레이션 결과를 DG-NMOS 구조에서 시행한 시뮬레이션 결과와의 비교를 통하여 CC-NMOS 구조에서 나타나는 CC 동작특성 메커니즘과, 이로 인한 전류 및 G$_{m}$의 상승을 확인하였다. 문턱 전압 이하 기울기, 문턱 전압 롤-오프, 드레인 유기 장벽 감소의 파라미터를 통하여 단채널 효과를 최소화하기 위한 디바이스 최적화를 수행하였다. 본 나노-스케일 전계 효과 트랜지스터를 위한 2차원 양자역학적 수치해석의 관한 연구를 통하여, CC-NMOS를 포함한 DG-MOSFET 구조가 40나노미터급 이하 MOSFET 소자의 물리적 한계를 극복하기 위한 이상적인 구조이며, 이와 같은 나노-스케일 소자의 해석에 있어서 양자역학적 모델링 및 시뮬레이션이 필수적임을 알 수 있었다.

Implementation of Differential Absorption LIDAR (DIAL) for Molecular Iodine Measurements Using Injection-Seeded Laser

  • Choi, Sungchul;Baik, Sunghoon;Park, Seungkyu;Park, Nakgyu;Kim, Dukhyeon
    • Journal of the Optical Society of Korea
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    • 제16권4호
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    • pp.325-330
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    • 2012
  • Differential absorption LIDAR (DIAL) is frequently used for atmospheric gas monitoring to detect impurities such as nitrogen dioxide, sulfur dioxide, iodine, and ozone. However, large differences in the on- and off-line laser wavelengths can cause serious errors owing to differential aerosol scattering. To resolve this problem, we have developed a new DIAL system for iodine vapor measurements in particular. The suggested DIAL system uses only one laser under seeded and unseeded conditions. To check the detection-sensitivity and error effects, we compared the results from a system using two seeded lasers with those from a system using a seeded and an unseeded laser. We demonstrate that the iodine concentration sensitivity of our system is improved in comparison to the conventional two seeded or two unseeded laser combinations.

산소가 제거된 310℃ 순수환경에서 CF8M 주조 스테인리스강의 환경 피로거동 - 수소 및 미세구조의 영향 (Environmental Fatigue Behaviors of CF8M Stainless Steel in 310℃ Deoxygenated Water - Effects of Hydrogen and Microstructure)

  • 장훈;조평연;장창희;김태순
    • 대한기계학회논문집A
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    • 제38권1호
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    • pp.11-16
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    • 2014
  • CF8M (11% ferrite) 주조 스테인리스강의 $310^{\circ}C$ 순수환경에서의 저주기피로 수명에 미치는 수소 및 미세구조의 영향을 분석하였다. CF8M 의 경우, 공기환경 대비 $310^{\circ}C$ 순수환경에서의 피로수명의 감소는 단조재인 316LN 에 비해 다소 작았다. 미세구조 및 파면 분석을 통해, CF8M 의 저주기피로 수명의 감소는 316LN 의 경우와 마찬가지로 수소유기균열에 의한 것으로 판단되었다. 그러나, CF8M 의 경우, 페라이트상 경계에 수소유기균열에 의한 2 차 균열이 빈번히 발생함에 따라 균열 선단에서의 응력집중이 저하되는 효과가 있었다. 이러한 응력집중의 완화로 인해 수소유기균열에 의한 피로균열진전이 둔화되어 결과적으로 저주기피로 수명의 저하가 완화되는 것으로 판단되었다.

Thermal conductivity of individual single-crystalline Bi nanowires grown by stress-induced recrystallization

  • Roh, Jong-Wook;Chen, Ren-Kun;Lee, Jun-Min;Ham, Jin-Hee;Lee, Seung-Hyn;Hochbaum, Allon;Hippalgaonkar, Kedar;Yang, Pei-Dong;Majumdar, Arun;Kim, Woo-Chul;Lee, Woo-Young
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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    • pp.23-23
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    • 2009
  • It has been challenging to increase the thermoelectric figure of merit ($ZT=S^2{\sigma}T/\kappa$) of materials, which determine the efficiency of thermoelectric devices, because the three parameters Seebeck coefficient (S), electrical conductivity ($\sigma$), and thermal conductivity ($\kappa$) of bulk materials are inter-dependent. With the development of nanotechnology, ZT values of nanostructured materials are predicted to be enhanced by classical size effects and quantum confinement effects. In particular, Bi nanowires were suggested as one of ideal thermoelectric materials due to the expected quantum confinement effects for the simultaneous increase in Sand. In this work, we have investigated the thermal conductivity of individual single crystalline Bi nanowires with d = 98 nm and d = 327 nm in the temperature range 40 - 300 K using MEMS devices. The for the Bi nanowire with d = 98 nm was observed to be ~ 1.6 W/m-K at 300 K, which is much lower than that of Bi bulk (8 W/m-K at 300 K). This indicates that the thermal conductivity of the Bi suppressed due to enhanced surface boundary scattering in one-dimensional structures. Our results suggest that Bi nanowires grown by stress-induced method can be used for high-efficiency thermoelectric devices.

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Semi-analytical Numerical Analysis of the Core-size and Electric-field Intensity Dependency of the Light Emission Wavelength of CdSe/ZnS Quantum Dots

  • Lee, Honyeon
    • 반도체디스플레이기술학회지
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    • 제20권3호
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    • pp.11-17
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    • 2021
  • I performed a semi-analytical numerical analysis of the effects of core size and electric field intensity on the light emission wavelength of CdSe/ZnS quantum dots (QDs). The analysis used a quantum mechanical approach; I solved the Schrödinger equation describing the electron-hole pairs of QDs. The numerical solutions are described using a basis set composed of the eigenstates of the Schrödinger equation; they are thus equivalent to analytical solutions. This semi-analytical numerical method made it simple and reliable to evaluate the dependency of QD characteristics on the QD core size and electric field intensity. As the QD core diameter changed from 9.9 to 2.5 nm, the light emission wavelength of CdSe core-only QDs varied from 262.9 to 643.8 nm, and that of CdSe/ZnS core/shell QDs from 279.9 to 697.2 nm. On application of an electric field of 8 × 105 V/cm, the emission wavelengths of green-emitting CdSe and CdSe/ZnS QDs increased by 7.7 and 3.8 nm, respectively. This semi-analytical numerical analysis will aid the choice of QD size and material, and promote the development of improved QD light-emitting devices.

양자가둠 효과를 포함한 Saddle MOSFET에서의 모서리효과의 분석과 억제방법 (Analysis and Suppression of the Corner Effect in a Saddle MOSFET Including Quantum Confinements Effects)

  • 셰드;김희상;라흐만;이종호;박병국;신형철
    • 대한전자공학회논문지SD
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    • 제47권3호
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    • pp.1-6
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    • 2010
  • Saddle MOSFET의 모서리의 효과에 대한 고전역학과 양자역학적 시뮬레이션의 비교분석을 3차원 수치 시뮬레이터를 사용하여 수행하였다. 비교분석 결과 양자역학적 시뮬레이션에서는 실리콘 핀의 단면에서의 정확한 최대 전자 밀도의 위치와 크기를 제공함으로써 소자의 정확한 설명을 제공하는 것을 보여 주었고, 이를 이용하여 모서리 효과 및 그것이 소자의 문턱전압의 특성을 미치는 영향의 정확한 분석이 실행되었다. 또한, 모서리 효과를 억제하기 위해서 실리콘 핀의 모서리를 둥글게 하거나 구석의 바디도핑을 낮추는 두 가지 가능한 기법을 제시했다.