• Title, Summary, Keyword: quantum double

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Quantum Modeling of Nanoscale Symmetric Double-Gate InAlAs/InGaAs/InP HEMT

  • Verma, Neha;Gupta, Mridula;Gupta, R.S.;Jogi, Jyotika
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.13 no.4
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    • pp.342-354
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    • 2013
  • The aim of this work is to investigate and study the quantum effects in the modeling of nanoscale symmetric double-gate InAlAs/InGaAs/InP HEMT (High Electron Mobility Transistor). In order to do so, the carrier concentration in InGaAs channel at gate lengths ($L_g$) 100 nm and 50 nm, are modelled by a density gradient model or quantum moments model. The simulated results obtained from the quantum moments model are compared with the available experimental results to show the accuracy and also with a semi-classical model to show the need for quantum modeling. Quantum modeling shows major variation in electron concentration profiles and affects the device characteristics. The two triangular quantum wells predicted by the semi-classical model seem to vanish in the quantum model as bulk inversion takes place. The quantum effects thus become essential to incorporate in nanoscale heterostructure device modeling.

Magnetic Resonance Imaging with Intermolecular Double Quantum Coherences

  • Ahn, Sang-Doo
    • Journal of the Korean Magnetic Resonance Society
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    • v.8 no.2
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    • pp.108-114
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    • 2004
  • Recently a new method for magnetic resonance imaging based on the detection of relatively strong signal from intermolecular multiple quantum coherences (iMQCs) is reported. Such a signal would not be observable in the conventional framework of magnetic resonance; it originates in long-range dipolar couplings that are traditionally ignored. In this paper, we present the results of experimental studies to assess the feasibility of intermolecular double quantum coherences (iDQCs) imaging in humans. We show that the iDQC images are readily observable at 4T and that they do indeed provide different contrast than appears in conventional images.

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Gate Tunneling Current and QuantumEffects in Deep Scaled MOSFETs

  • Choi, Chang-Hoon;Dutton, Robert W.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.4 no.1
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    • pp.27-31
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    • 2004
  • Models and simulations of gate tunneling current for thinoxide MOSFETs and Double-Gate SOIs are discussed. A guideline in design of leaky MOS capacitors is proposed and resonant gate tunneling current in DG SOI simulated based on quantum-mechanicalmodels. Gate tunneling current in fully-depleted, double-gate SOI MOSFETs is characterized based on quantum-mechanical principles. The simulated $I_G-V_G$ of double-gate SOI has negative differential resistance like that of the resonant tunnel diodes.

Analysis of Short Channel Effects Using Analytical Transport Model For Double Gate MOSFET

  • Jung, Hak-Kee
    • Journal of information and communication convergence engineering
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    • v.5 no.1
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    • pp.45-49
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    • 2007
  • The analytical transport model in subthreshold regime for double gate MOSFET has been presented to analyze the short channel effects such as subthreshold swing, threshold voltage roll-off and drain induced barrier lowering. The present approach includes the quantum tunneling of carriers through the source-drain barrier. Poisson equation is used for modeling thermionic emission current, and Wentzel-Kramers-Brillouin approximations are applied for modeling quantum tunneling current. This model has been used to investigate the subthreshold operations of double gate MOSFET having the gate length of the nanometer range with ultra thin gate oxide and channel thickness under sub-20nm. Compared with results of two dimensional numerical simulations, the results in this study show good agreements with those for subthreshold swing and threshold voltage roll-off. Note the short channel effects degrade due to quantum tunneling, especially in the gate length of below 10nm, and DGMOSFETs have to be very strictly designed in the regime of below 10nm gate length since quantum tunneling becomes the main transport mechanism in the subthreshold region.

Quantum Mechanical Calculation of Two-Dimensional Electron Gas Density in AlGaAs/GaAs/AlGaAs Double-Heterojunction HEMT Structures (AlGaAs/GaAs/AlGaAs 이중 이종집합 HEMT 구조에서의 2차원 전자개스 농도의 양자역학적 계산)

  • 윤경식;이정일;강광남
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.29A no.3
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    • pp.59-65
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    • 1992
  • In this paper, the Numerov method is applied to solve the Schroedinger equation for $Al_{0.3}Ga_{0.7}AS/GaAs/Al_{0.3}Ga_{0.7}As$ double-heterojunction HEMT structures. The 3 subband energy levels, corresponding wave functions, 2-dimensional electron gas density, and conduction band edge profile are calculated from a self-consistent iterative solution of the Schroedinger equation and the Poisson equation. In addition, 2-dimensional electron gas densities in a quantum well of double heterostructure are calculated as a function of applied gate voltage. The density in the double heterojunction quantum well is increased to about more than 90%, however, the transconductance of the double heterostructure HEMT is not improved compared to that of the single heterostructure HEMT. Thus, double-heterojunction structures are expected to be suitable to increase the current capability in a HEMT device or a power HEMT structure.

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Breakthrough of Single-Quantum Signal in Double-Quantum Filtering and its Elimination

  • Jung, K.J.;Katz, J.;Hilal, S.K.;Cho, Z.H.
    • Proceedings of the KOSOMBE Conference
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    • v.1993 no.05
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    • pp.86-89
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    • 1993
  • Breakthrough of single-quantum coherence is shown to occur even after application of a double-quantum filter with Bax's four-step phase-cycling scheme. The reason for this breakthrough is investigated and a method for its elimination is theoretically developed and experimentally demonstrated.

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2D Quantum Effect Analysis of Nanoscale Double-Gate MOSFET (이차원 양자 효과를 고려한 극미세 Double-Gate MOSFET)

  • Kim, Ji-Hyun;Son, Ae-Ri;Jeong, Na-Rae;Shin, Hyung-Soon
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.45 no.10
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    • pp.15-22
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    • 2008
  • The bulk-planer MOSFET has a scaling limitation due to the short channel effect (SCE). The Double-Gate MOSFET (DG-MOSFET) is a next generation device for nanoscale with excellent control of SCE. The quantum effect in lateral direction is important for subthreshold characteristics when the effective channel length of DG-MOSFET is less than 10nm, Also, ballistic transport is setting important. This study shows modeling and design issues of nanoscale DG-MOSFET considering the 2D quantum effect and ballistic transport. We have optimized device characteristics of DG-MOSFET using a proper value of $t_{si}$ underlap and lateral doping gradient.

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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    • v.32 no.4
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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.

Poly-gate Quantization Effect in Double-Gate MOSFET (폴리 게이트의 양자효과에 의한 Double-Gate MOSFET의 특성 변화 연구)

  • 박지선;이승준;신형순
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.41 no.8
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    • pp.17-24
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    • 2004
  • Quantum effects in the poly-gate are analyzed in two dimensions using the density-gradient method, and their impact on the short-channel effect of double-gate MOSFETs is investigated. The 2-D effects of quantum mechanical depletion at the gate to sidewall oxide is identified as the cause of large charge-dipole formation at the corner of the gate. The bias dependence of the charge dipole shows that the magnitude of the dipole peak-value increases in the subthreshold region and there is a large difference in carrier and potential distribution compared to the classical solution. Using evanescent-nude analysis, it is found that the quantum effect in the poly-gate substantially increases the short-channel effect and it is more significant than the quantum effect in the Si film. The penetration of potential contours into the poly-gate due to the dipole formation at the drain side of the gate corner is identified as the reason for the substantial increase in short-channel effects.

ON HOPF ALGEBRAS IN ENTROPIC JÓNSSON-TARSKI VARIETIES

  • ROMANOWSKA, ANNA B.;SMITH, JONATHAN D.H.
    • Bulletin of the Korean Mathematical Society
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    • v.52 no.5
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    • pp.1587-1606
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    • 2015
  • Comonoid, bi-algebra, and Hopf algebra structures are studied within the universal-algebraic context of entropic varieties. Attention focuses on the behavior of setlike and primitive elements. It is shown that entropic $J{\acute{o}}nsson$-Tarski varieties provide a natural universal-algebraic setting for primitive elements and group quantum couples (generalizations of the group quantum double). Here, the set of primitive elements of a Hopf algebra forms a Lie algebra, and the tensor algebra on any algebra is a bi-algebra. If the tensor algebra is a Hopf algebra, then the underlying $J{\acute{o}}nsson$-Tarski monoid of the generating algebra is cancellative. The problem of determining when the $J{\acute{o}}nsson$-Tarski monoid forms a group is open.