共查询到20条相似文献,搜索用时 0 毫秒
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L. I. Glazman 《Journal of Low Temperature Physics》2000,118(5-6):247-269
This is a brief review of some recent developments inexperiments and theory of the Coulomb blockade phenomenon. Weconcentrate on electron tunneling through semiconductorquantum dots and normal-metal nanoparticles. The linearconductance and non-linear I–V characteristics are sensitivenot only to the charging energy, but also to smaller energyscales. These are the spacing between discrete energy levelsof intra-dot electron excitations, and the width these levelsacquire due to the electron escape to leads through thejunctions. At sufficiently low temperatures, or at not-so-small junction conductances, the many-body phenomena, such asKondo effect, become observable in the dot-lead system. Kondoeffect yields an additional fine energy scale to the problem.We discuss a simple theoretical model incorporating theseenergy scales, and its relation to the experimentalobservations. 相似文献
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Sergey E. Kubatkin Andrey V. Danilov Håkan Olin Tord Cleason 《Journal of Low Temperature Physics》2000,118(5-6):307-316
Quench-condensed bismuth films of 3–5 nm thickness have beenused as a cluster source to prepare Single ElectronTransistors (SET) based on a single cluster with high chargingenergy. We used electron-beam defined shadow evaporation masksto pattern 10 nm wide constrictions in these films. Byincremental depositions through these masks controlled by insitu sample conductance measurements, we obtained a SETgeometry for clusters with charging energies up to 90 meV. Ourexperiment showed that the SET geometry can be achieved inevery sample preparation run, despite the apparent randomnature of cluster formation in granular films. The resultingcharging energy of the transistor varied from experiment toexperiment. Its value, however, was always higher than 10 meV. 相似文献
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Single Nucleobase Identification Using Biophysical Signatures from Nanoelectronic Quantum Tunneling 下载免费PDF全文
Lee E. Korshoj Sepideh Afsari Sajida Khan Anushree Chatterjee Prashant Nagpal 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(11)
Nanoelectronic DNA sequencing can provide an important alternative to sequencing‐by‐synthesis by reducing sample preparation time, cost, and complexity as a high‐throughput next‐generation technique with accurate single‐molecule identification. However, sample noise and signature overlap continue to prevent high‐resolution and accurate sequencing results. Probing the molecular orbitals of chemically distinct DNA nucleobases offers a path for facile sequence identification, but molecular entropy (from nucleotide conformations) makes such identification difficult when relying only on the energies of lowest‐unoccupied and highest‐occupied molecular orbitals (LUMO and HOMO). Here, nine biophysical parameters are developed to better characterize molecular orbitals of individual nucleobases, intended for single‐molecule DNA sequencing using quantum tunneling of charges. For this analysis, theoretical models for quantum tunneling are combined with transition voltage spectroscopy to obtain measurable parameters unique to the molecule within an electronic junction. Scanning tunneling spectroscopy is then used to measure these nine biophysical parameters for DNA nucleotides, and a modified machine learning algorithm identified nucleobases. The new parameters significantly improve base calling over merely using LUMO and HOMO frontier orbital energies. Furthermore, high accuracies for identifying DNA nucleobases were observed at different pH conditions. These results have significant implications for developing a robust and accurate high‐throughput nanoelectronic DNA sequencing technique. 相似文献
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基于单片机的宽带高精度频率计设计 总被引:2,自引:0,他引:2
介绍一种基于单片机的宽带高精度变闸门频率测试法,并给出该方法的测试原理及软、硬件组成.本设计以AT89C51单片机为测频的核心器件,用单片机的软件控制程序取代复杂的外计数电路,从而达到简化电路,提高测量精度的目的.总体看来,该设计具有结构简单,功能齐全,使用方便的特点. 相似文献
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Wancheng Zhang Nan-Jian Wu Hashizume T. Kasai S. 《Nanotechnology, IEEE Transactions on》2007,6(2):146-157
This paper proposes two kinds of novel hybrid voltage controlled ring oscillators (VCO) using a single electron transistor (SET) and metal-oxide-semiconductor (MOS) transistor. The novel SET/MOS hybrid VCO circuits possess the merits of both the SET circuit and the MOS circuit. The novel VCO circuits have several advantages: wide frequency tuning range, low power dissipation, and large load capability. We use the SPICE compact macro model to describe the SET and simulate the performances of the SET/MOS hybrid VCO circuits by HSPICE simulator. Simulation results demonstrate that the hybrid circuits can operate well as a VCO at room temperature. The oscillation frequency of the VCO circuits could be as high as 1 GHz, with a -71 dBc/Hz phase noise at 1 MHz offset frequency. The power dissipations are lower than 2 uW. We studied the effect of fabrication tolerance, background charge, and operating temperature on the performances of the circuits 相似文献
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H. Sakata A. Katagiri M. Yokoi T. Kato H. Morimoto 《Journal of Low Temperature Physics》2003,131(3-4):275-279
We have measured the tunneling spectra in Bi2Sr2CaCu2O8 with a scanning tunneling microscope(STM) at various tip-sample distances by changing the tunneling conductance in a controlled manner. When the tunneling conductance is increased from 1×10–9 to 1×10–5 S, the spectra do not show changes in particular. However, the gap value decreases steeply and the asymmetric back ground density of states turns inverted V-shaped one above 6×10–4 S. The changes in the tunneling spectra at the high tunneling conductances are explained by the enhancement of the local carrier density induced by the pressure that the STM tip applied to the sample. 相似文献
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The alkali metals Cs and Rb are the only surfaces which are not wetted by superfluid
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He below a certain temperature. In our experiments, using the photoelectron tunneling method, we can highly resolve the growth of the non-wetting thin-film state of
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He on a quench-condensed Cs surface. It turns out that far from coexistence there is little adsorption of helium. In contrast, close to coexistence a rapid growth up to two monolayers of helium is observed, but the surface is still non-wet under the usual convention. 相似文献
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Vladimir Bubanja 《Journal of Low Temperature Physics》2014,175(3-4):564-579
We consider the influence of the electromagnetic fluctuations on the transport properties of a hybrid single electron transistor, consisting of superconducting electrodes and a normal-metal island, when operated as a turnstile. We derive the analytic expressions for the rates near the thresholds of single electron tunneling, Andreev reflection, and Cooper-pair–electron cotunneling processes. These results show that the dissipative on-chip impedance suppresses the rates of the undesirable higher-order tunneling processes much stronger than the single electron tunneling which can therefore be utilized to increase the accuracy of such a device in quantum metrological applications. 相似文献
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Ultrafast Magnetization Manipulation Using Single Femtosecond Light and Hot‐Electron Pulses 下载免费PDF全文
Yong Xu Marwan Deb Grégory Malinowski Michel Hehn Weisheng Zhao Stéphane Mangin 《Advanced materials (Deerfield Beach, Fla.)》2017,29(42)
Current‐induced magnetization manipulation is a key issue for spintronic applications. This manipulation must be fast, deterministic, and nondestructive in order to function in device applications. Therefore, single‐ electronic‐pulse‐driven deterministic switching of the magnetization on the picosecond timescale represents a major step toward future developments of ultrafast spintronic systems. Here, the ultrafast magnetization dynamics in engineered Gdx [FeCo]1?x ‐based structures are studied to compare the effect of femtosecond laser and hot‐electron pulses. It is demonstrated that a single femtosecond hot‐electron pulse causes deterministic magnetization reversal in either Gd‐rich and FeCo‐rich alloys similarly to a femtosecond laser pulse. In addition, it is shown that the limiting factor of such manipulation for perpendicular magnetized films arises from the formation of a multidomain state due to dipolar interactions. By performing time‐resolved measurements under various magnetic fields, it is demonstrated that the same magnetization dynamics are observed for both light and hot‐electron excitation, and that the full magnetization reversal takes place within 40 ps. The efficiency of the ultrafast current‐induced magnetization manipulation is enhanced due to the ballistic transport of hot electrons before reaching the GdFeCo magnetic layer. 相似文献
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The melting point of uranium dioxide was measured as a function of isostatic pressure in an autoclave filled with helium up to 0.25 GPa. Containerless laser surface-heating was applied to measure the melting point by thermal arrest measurements during sample cooling. Precise control of the cooling rate, aimed at a precise determination of the freezing plateau, was obtained with a two-pulse method, where two Nd:YAG high power laser pulses are mixed within the same optical fiber and then focused on the sample surface. Calibration of the power of the two pulses permits the measurement of the melting point with very low uncertainty (0.5%). The measured melting slope of UO2 is 170 and 200 KGPa–1, a value which is markedly higher than that predicted by the Clausius–Clapeyron equation, which expresses this slope in terms of the enthalpy of fusion and the melting expansion. Possible reasons for this discrepancy are discussed. 相似文献
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为降低加速器运行的热负载和提高束流质量,抑制电子云效应成为未来粒子加速器设计和建造过程中的基本要求。二次电子产额(SEY)是电子云现象产生的主要因素之一,它代表材料表面产生二次电子的能力。激光刻蚀技术是一种通过修改材料表面微观形貌从而抑制二次电子发射的方法,它具有操作简单,重复性高等优点。为评估激光刻蚀技术的工程应用潜力,本文搭建一台低温二次电子产额测试系统。以不同图案对无氧铜样品进行激光刻蚀,研究样品在不同温度下的二次电子发射特性曲线。扫描电子显微镜测试结果显示,刻蚀后的样品表面存在规则的沟壑结构和球状结构。低温下材料表面SEY受吸附气体层和基底固有属性的共同作用的影响,同时基底的微观形貌也影响二次电子发射的能力。 相似文献
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A method has been developed for measuring the dependence of the electron probe diameter d in a scanning electron microscope SEM on the beam current J. The relationship for the CAMSCAN CS-44 SEM is d(J) ~ J
1/4, whereas electron probe formation theory gives d(J) ~ J
3/8; the reasons for these differences are considered. 相似文献
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V. M. Bogomol'nyi 《Measurement Techniques》2003,46(11):1079-1083
The conditions for resonance oscillations of the current and the electromagnetic field to occur in metal-dielectric-metal structures when acted upon by a constant external electric field are determined, taking into account the electron emission in the dielectric from microprotuberances on the surface of the metal electrodes. A physical model of self-excited wave processes which occur in the initial reversible stage of electric breakdown of a thin dielectric layer is formulated. 相似文献