共查询到18条相似文献,搜索用时 171 毫秒
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目前研究准弹道输运纳米MOSFET散粒噪声的抑制时, 采取了完全不考虑其抑制, 或只强调抑制的存在而并未给出抑制公式的方式进行研究. 本文基于Navid模型推导了准弹道输运纳米MOSFET散粒噪声, 并得到了其在费米作用、库仑作用和二者共同作用三种情形下的抑制因子. 在此基础上, 对各抑制因子随源漏电压、栅极电压、温度及源漏掺杂浓度的变化特性进行了研究. 两者共同作用的抑制因子随源漏电压和栅极电压变化特性与文献中给出的实验结论相符合, 从而对实验上得到两者共同作用下的抑制因子随源漏电压和栅极电压的变化特性给出了理论解释. 相似文献
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根据电荷通过低温量子导体时具有的二项分布导致散粒噪声这一结论,结合Landauer电流公式的物理内涵建立了相干介观系统中的散粒噪声模型,并通过Monte Carlo模拟方法产生了散粒噪声时间序列.介观系统中散粒噪声的抑制来源于电子输运时的相关性,传输本征值双峰分布导致量子混沌腔和无序金属中的散粒噪声抑制.根据这两个结论,通过Monte Carlo模拟定性地分析了传输本征值分布与电子输运相关性之间的关系.
关键词:
散粒噪声
Landauer公式
介观系统 相似文献
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《物理学报》2020,(17)
随着金属-氧化物半导体场效应晶体管(MOSFET)器件的尺寸进入到纳米量级,器件的噪声机理逐渐开始转变.传统的热噪声与漏源电流模型精度出现下降,散粒噪声成为器件噪声不可忽略的因素.本文通过求解能量平衡方程,推导了短沟道MOSFET器件的沟道电子温度和电子速度表达式,由此建立了漏源电流模型;基于漏源电流模型建立了适用于40 nm以下器件的散粒噪声模型和热噪声模型.研究了n型金属-氧化物半导体场效应晶体管(NMOSFET)器件在不同偏置电压下,器件尺寸对散粒噪声抑制因子和噪声机理的影响.研究表明:已有的热噪声模型与散粒噪声模型的精度随着器件尺寸的减小而下降,导致相应的散粒噪声抑制因子被高估.当NMOSFET器件的尺寸减小到10 nm时,器件的噪声需由热噪声与受抑制的散粒噪声共同表征.本文建立的短沟道器件散粒噪声模型可应用于纳米尺寸NMOSFET器件噪声性能的分析与建模. 相似文献
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介观体系输运过程中载流子的离散性导致了散粒噪声.通过测量散粒噪声可以得到传统的基于时间平均值的电导测量无法得到的随时间涨落信息,因而作为一种重要手段在极低温量子输运研究中得到了一定的应用.极低温环境下的噪声测量是一种难度很大的极端条件下的微弱信号测量,通常需要在低温端安装前置放大器并且尽量靠近待测器件以提高测量信噪比和带宽,因此对放大器的噪声水平和功耗都有严格的要求.提出了在稀释制冷机内搭建的散粒噪声测量系统,以及利用此套系统得到了在mK温区超导隧道结散粒噪声的测量结果.自行研制的高电子迁移率晶体管低温前置放大器采用整体封装,便于安装在商用干式稀释制冷机的4 K温区,本底电压噪声为0.25 nV/√Hz,功耗仅为0.754 mW.通过对隧道结进行散粒噪声测量,得到的Fano因子和理论计算吻合. 相似文献
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利用密度泛函理论结合非平衡格林函数方法,研究了不同拓扑能带结构的石墨烯电极分子器件输运特性.结果表明器件导通电压与电极禁带宽度正相关,同时器件在输运过程中表现出负微分电阻特性,峰谷电流比可达2697.分析认为器件导通源自于偏压升高过程中两电极能带匹配.器件负微分电阻特性源自于偏压升高过程中两电极能带交错.散射态分析表明,能带匹配后散射态分布较为离域,有利于电子通过器件.能带交错后散射态局域于电极处,表明电子输运受到抑制. 相似文献
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为改善碳纳米管场效应晶体管的性能,将一种峰值掺杂-低掺杂漏(HALO-LDD)掺杂结构引入碳纳米管沟道.在量子力学非平衡Green函数理论框架内,通过自洽求解Poisson方程和Schrödinger方程,构建了适用于非均匀掺杂的碳纳米管场效应管的输运模型,该模型可实现场效应晶体管的输运性质与碳纳米管手性指数的对接. 利用该模型研究了单HALO双LDD 掺杂结构对碳纳米管场效应晶体管输运特性的影响.对比分析表明,这种非均匀掺杂结构的场效应管同本征碳纳米管沟道场效应晶体管相比,具有更低的泄漏电流、更大的电流开关比、更小的亚阈区栅电压摆幅,表明其具有更好的栅控能力; 具有更小的漏源电导,更适合应用于模拟集成电路中;具有更小的阈值电压漂移,表明更能抑制短沟道效应. 同本征沟道碳纳米管场效应晶体管相比,这种非均匀掺杂碳纳米管场效应晶体管在沟道区靠近源端位置,电场强度增大, 有利于增大电子的传输速率;在沟道区靠近漏端位置,电场强度减小,更有利于抑制热电子效应. 相似文献
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Q. Chen H. -K. Zhao 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(2):237-248
We have investigated the spectral density of shot noise for an ultra-small quantum dot(QD) system in the Coulomb blockade
regime when irradiated with microwave fields (MWFs) by employing a nonequilibrium Green’s function technique. The shot noise
is sensitive to Coulomb interaction, and the photon-assisted Coulomb blockade behaviour strongly modifies the mesoscopic transport.
We have calculated the first and second derivatives of shot noise in the strong and weak coupling regimes to compare the theoretical
results with existing experimental results. In the strong coupling regime, the first and second derivatives of shot noise
display Fano type peak-valley structures around the charging channel 2E
c
due to Coulomb interaction. When the magnitudes of the MWFs are sufficiently large, the system displays channel blockade
due to photon irradiation. The photon-assisted and Coulomb blockade steps in the noise — as well as the resonant behaviour
in the differential noise — are smeared by increasing temperature. The Coulomb interaction suppresses the shot noise, but
the ac fields can either suppress the shot noise(balanced case) or enhance the shot noise(unbalanced case). The suppression
of shot noise caused by ac fields in the balanced case is greater than that caused by Coulomb interaction in our system. Super-Poissonian
shot noise may be induced due to the compound effects of strong Coulomb interaction and photon absorption-emission processes. 相似文献
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We investigate the effects of dephasing on the current statistics of mesoscopic conductors with a recently developed statistical model, focusing, in particular, on mesoscopic cavities and Aharonov-Bohm rings. For such devices, we analyze the influence of an arbitrary degree of decoherence on the cumulants of the current. We recover known results for the limiting cases of fully coherent and totally incoherent transport and are able to obtain detailed information on the intermediate regime of partial coherence for a varying number of open channels. We show that dephasing affects the average current, shot noise, and higher order cumulants in a quantitatively and qualitatively similar way, and that consequently shot noise or higher order cumulants of the current do not provide information on decoherence additional or complementary to what can be already obtained from the average current. 相似文献
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G. B. Lesovik 《JETP Letters》1999,70(3):208-215
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We derive general expressions for the current and the shot noise, taking into account non-Markovian memory effects. In generalization of previous approaches, our theory is valid for an arbitrary Coulomb interaction and coupling strength and is applicable to quantum dots and more complex systems such as molecules. A fully consistent diagrammatic expansion up to second order in the coupling strength, taking into account cotunneling processes, allows for a study of transport in an intermediate coupling strength regime relevant to many current experiments. We discuss a single-level quantum dot as a first example, focusing on the Coulomb-blockade regime where the cotunneling processes dominate. We find super-Poissonian shot noise due to inelastic spin-flip cotunneling processes at an energy scale different from the one expected from first-order calculations. 相似文献
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S. -H. Ouyang C. -H. Lam J. Q. You 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(1):67-72
We study electron transport through a quantum dot, connected to non-magnetic leads, in a magnetic field. A super-Poissonian
electron noise due to the effects of both interacting localized states and dynamic channel blockade is found when the Coulomb
blockade is partially lifted. This is sharp contrast to the sub-Poissonian shot noise found in the previous studies for a
large bias voltage, where the Coulomb blockade is completely lifted. Moreover, we show that the super-Poissonian shot noise
can be suppressed by applying an electron spin resonance (ESR) driving field. For a sufficiently strong ESR driving field
strength, the super-Poissonian shot noise will change to be sub-Poissonian. 相似文献
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Coulomb drag shot noise has been studied theoretically for 1D interacting electron systems, which are realized, e.g., in single-wall nanotubes. We show that under adiabatic coupling to external leads, the Coulomb drag shot noise of two coupled or crossed nanotubes contains surprising effects, in particular, a complete locking of the shot noise in the tubes. In contrast to Coulomb drag of the average current, the noise locking is based on a symmetry of the underlying Hamiltonian and is not limited to asymptotically small energy scales. 相似文献
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We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling. 相似文献
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An interplay between charge discreteness, coherent scattering, and Coulomb interaction yields nontrivial effects in quantum transport. We derive a real-time effective action and an equivalent quantum Langevin equation for an arbitrary coherent scatterer and evaluate its current-voltage characteristics in the presence of interactions. Within our model, at large conductances G0 and low T (but outside the instanton-dominated regime), the interaction correction to G0 saturates and causes conductance suppression by a universal factor which depends only on the type of the conductor. 相似文献