共查询到20条相似文献,搜索用时 62 毫秒
1.
具有特定边界的石墨烯纳米结构在纳电子学、自旋电子学等研究领域表现出良好的应用前景.然而石墨烯加工成纳米结构时,无序的边界不可避免地会降低其载流子迁移率.氢等离子体各向异性刻蚀技术是加工具备完美边界石墨烯微纳结构的一项关键技术,刻蚀后的石墨烯呈现出规则的近原子级平整的锯齿形边界.本文研究了氮化硼上锯齿形边界石墨烯反点网络的磁输运性质,低磁场下可以观测到载流子围绕着一个空位缺陷运动时的公度振荡磁阻峰.随着磁场的增大,朗道能级简并度逐渐增大,载流子的磁输运行为从Shubnikov-de Haas振荡逐渐向量子霍尔效应转变.在零磁场附近可以观测到反点网络周期性空位缺陷的边界散射所导致的弱局域效应.研究结果表明,在氮化硼衬底上利用氢等离子体刻蚀技术加工锯齿形边界石墨烯反点网络,其样品质量会明显提高,这种简单易行的方法为后续高质量石墨烯反点网络的输运研究提供了新思路. 相似文献
2.
应变锗空穴量子点是实现超大规模量子计算最有前景的平台之一.由于锗空穴不受超精细相互作影响,有着较长的自旋弛豫时间和量子退相干时间,且锗中本征的强旋轨道耦合和空穴载流子的低有效质量,使得全电场操控空穴自旋量子比特得以实现,极大地降低了器件加工难度,增加了量子点的可扩展性.本文介绍了一种使用应变锗异质结制备重叠栅空穴双量子点器件的方法,完成了应变锗异质结性质测量,空穴双量子点器件制作,单量子点输运性质和双量子点输运性质研究,双量子点耦合可研究调节性研究,以及外磁场存在下的漏电流性质研究和泡利自旋阻塞解除机制的研究.这些工作为未来实现高质量自旋量子比特制备和高保真度量子逻辑门操控提供了实验平台和基本参数. 相似文献
3.
Coulomb blockade and hopping transport behaviors of donor-induced quantum dots in junctionless transistors
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The ionized dopants, working as quantum dots in silicon nanowires, exhibit potential advantages for the development of atomic-scale transistors. We investigate single electron tunneling through a phosphorus dopant induced quantum dots array in heavily n-doped junctionless nanowire transistors. Several subpeaks splittings in current oscillations are clearly observed due to the coupling of the quantum dots at the temperature of 6 K. The transport behaviors change from resonance tunneling to hoping conduction with increased temperature. The charging energy of the phosphorus donors is approximately 12.8 meV. This work helps clear the basic mechanism of electron transport through donor-induced quantum dots and electron transport properties in the heavily doped nanowire through dopant engineering. 相似文献
4.
S. M.-M. Dubois Z. Zanolli X. Declerck J.-C. Charlier 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,72(1):1-24
Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) represent
a novel class of low-dimensional materials.
All these graphene-based nanostructures are expected to display the
extraordinary electronic, thermal and mechanical properties of graphene
and are thus promising candidates for a wide range of nanoscience
and nanotechnology applications.
In this paper, the electronic and quantum transport properties
of these carbon nanomaterials are reviewed. Although these systems
share the similar graphene electronic structure, confinement effects are
playing a crucial role. Indeed, the lateral confinement of charge carriers
could create an energy gap near the charge neutrality point, depending
on the width of the ribbon, the nanotube diameter, the stacking of the
carbon layers regarding the different crystallographic orientations involved.
After reviewing the transport properties of defect-free systems, doping
and topological defects (including edge disorder) are also proposed as
tools to taylor the quantum conductance in these materials.
Their unusual electronic and transport properties promote these carbon
nanomaterials as promising candidates for new building blocks in a future
carbon-based nanoelectronics, thus opening alternatives to present
silicon-based electronics devices. 相似文献
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The successful fabrication of single layer graphene has greatly stimulated the progress of the research on graphene. In this
article, focusing on the basic electronic and transport properties of graphene nanoribbons (GNRs), we review the recent progress
of experimental fabrication of GNRs, the theoretical and experimental investigations of physical properties, and device applications
of GNRs. We also briefly discuss the research efforts on the spin polarization of GNRs in relation to the edge states.
相似文献
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基于第一性原理电子结构和输运性质计算,研究了单空位缺陷对单层石墨纳米带(包括zigzag型和armchair型带)电子性质的影响.研究发现,单空位缺陷使石墨纳米带在费米面上出现一平直的缺陷态能带;单空位缺陷的引入使zigzag型半导体性的石墨纳米带变为金属性,这在能带工程中有重要的应用价值;奇数宽度的armchair型石墨纳米带表现出金属特性,有着很好的导电性能,同时,偶数宽度的armchair型石墨带虽有金属性的能带结构,但却有类似半导体的伏安特性;单空位缺陷使得奇数宽度的armchair石墨纳米带导电
关键词:
石墨纳米带
单空位缺陷
电子结构
输运性质 相似文献
9.
We study electronic transport through an n-p junction in graphene irradiated by an electromagnetic field (EF). In the absence of EF one may expect the perfect transmission of quasiparticles flowing perpendicular to the junction. We show that the resonant interaction of propagating quasiparticles with the EF induces a dynamic gap between electron and hole bands in the quasiparticle spectrum of graphene. In this case the strongly suppressed quasiparticle transmission is only possible due to interband tunneling. The effect may be used to control transport properties of diverse structures in graphene, e.g., n-p-n transistors and quantum dots, by variation of the intensity and frequency of the external radiation. 相似文献
10.
Different technological approaches for creating graphene quantum dots by the adsorption of hydrogen atoms are considered.
The adsorption can occur both at convex portions of a distorted graphene nanoribbon and in the structure formed by two distorted
graphene nanoribbon rows superimposed on each other at the places free from the ribbon crossings. It is shown that settlement
of hydrogen atoms at convex portions of the nanoribbons is energetically favorable. This gives rise to the creation of insulating
graphane (CH) nanodomains separating the conducting regions. As a result, a graphene quantum dot appears. The variation of
the electron spectra of graphene quantum dots with the length of these graphane regions is discussed. 相似文献
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Spin-polarized transport in a normal/ferromagnetic/normal zigzag graphene nanoribbon junction
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We investigate the spin-dependent electron transport in single and double normal/ferromagnetic/normal zigzag graphene nanoribbon (NG/FG/NG) junctions. The ferromagnetism in the FG region originates from the spontaneous magnetization of the zigzag graphene nanoribbon. It is shown that when the zigzag-chain number of the ribbon is even and only a single transverse mode is actived, the single NG/FG/NG junction can act as a spin polarizer and/or a spin analyzer because of the valley selection rule and the spin-exchange field in the FG, while the double NG/FG/NG/FG/NG junction exhibits a quantum switching effect, in which the on and the off states switch rapidly by varying the cross angle between two FG magnetizations. Our findings may shed light on the application of magnetized graphene nanoribbons to spintronics devices. 相似文献
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We investigate the quantum transport through zigzag graphene nanoribbons with embedded “5-7-5”-edge line defects, by means of the non-equilibrium Green's function technique. It is found that when two semi-infinite line defects exist in the nanoribbon, notable Fano antiresonance takes place in the quantum transport process, which enables to drive the apparent thermoelectric effect. We propose this structure to be a promising candidate for improving the thermoelectric efficiency based on graphene nanoribbons. 相似文献
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采用第一性原理电子结构和输运性质计算研究了zigzag型单层石墨纳米带(具有armchair 边缘)的电子结构和输运性质及其边缘空位缺陷效应. 研究发现,完整边缘的zigzag型石墨纳米带是具有一定能隙的半导体带,边缘空位缺陷的存在使得纳米带能隙变小,且缺陷浓度越大,能隙越小,并发生了半导体-金属转变. 利用这些研究结果,将有助于在能带工程中实现其电子结构裁剪.
关键词:
石墨纳米带
空位缺陷
电子结构
输运性质 相似文献
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H. B. Heersche P. Jarillo-Herrero J. B. Oostinga L. M.K. Vandersypen A. F. Morpurgo 《The European physical journal. Special topics》2007,148(1):27-37
The electronic transport properties of graphene exhibit
pronounced differences from those of conventional two dimensional
electron systems investigated in the past. As a consequence, well
established phenomena such as the integer quantum Hall effect and
weak localization manifest themselves differently in graphene. Here
we present an overview of recent experiments that we have performed
to probe phase coherent transport. In particular, we have
investigated in great detail Josephson supercurrent and
superconducting proximity effect in junctions consisting of a
graphene layer in between superconducting electrodes. We have also
used the same devices to measure aperiodic conductance fluctuations
and weak localization. The experimental results clearly indicate
that low-temperature transport in graphene is phase coherent on a
∼ 1μm length scale, irrespective of the position of the
Fermi level. We discuss the different behavior of Josephson
supercurrent and weak localization in terms of the unusual
properties of the electronic states in graphene upon time reversal
symmetry. 相似文献
19.
Stefan Krompiewski 《Central European Journal of Physics》2011,9(2):369-371
This contribution reports on charge and spin transport through graphene nanoribbons (GrNs) and carbon nanotubes (CNTs). The
paper focuses on the giant magnetoresistance effect in these materials, and their potential usefulness for spintronic applications.
As examples, the following devices are shortly discussed: GrNs in the ballistic transport regime, a CNT-based Schottky-barrier
field effect transistor (CNT SB-FET), as well as CNT quantum dots in the Coulomb blockade limit. 相似文献
20.
Bottom-up fabrication of graphene nanoribbons (GNRs) from halogen-terminated aromatic precursors is a promising method for achieving atomically precise nanoribbons at competitive yields. GNR fabrication proceeds via the polymerization of the precursors and successive dehydrogenation. By first principles density functional theory calculations, we perform a systematic characterization of the polymeric precursors and the corresponding graphene nanoribbons in terms of structural and electronic properties, and we compute the Raman and infrared spectra. The band structure properties are examined by considering the bonding features and the partial charge densities of the structures. The physical origin of the infrared and Raman peaks is investigated in terms of the morphology and vibrational properties of the precursors and products. We show that light spectroscopy provides a unique fingerprint for each type of GNR, which may be used to monitor the quality of the final products and the kinetics of the synthesis process. 相似文献