Quantum interference and Klein tunnelling in graphene heterojunctions
Quantum interference and Klein tunnelling in graphene heterojunctions
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DOI：
10.1038/nphys1198
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发表时间：
2009-03-01
期刊：
影响因子：
19.6
通讯作者：
Kim, Philip
中科院分区：
文献类型：
--
作者：
Young, Andrea F.;Kim, Philip
传统上，观察介观系统中的量子电导振荡需要将载流子限制在降维的相空间中(1-4)。尽管诸如透镜(5)和聚焦(6)之类的电子光学已经在实验中得到了证明，但由于难以创建电子波长数量级的尖锐静电势垒，在两个无约束维度中构建准直电子干涉仪仍然是一个挑战(7)。在这里，我们报告了在极窄的石墨烯异质结构中观察到的电导振荡，其中在两个静电创建的双极结之间形成谐振腔。振荡分析证实 p-n 结对弹道传输的载流子具有准直效应 (8)。在低磁场下的电导条纹中观察到的相移是通常入射在结上的载流子完美传输的标志(9)，因此构成了“克莱因隧道效应”(10-12) 的直接实验观察。
The observation of quantum conductance oscillations in mesoscopic systems has traditionally required the confinement of the carriers to a phase space of reduced dimensionality(1-4). Although electron optics such as lensing(5) and focusing(6) have been demonstrated experimentally, building a collimated electron interferometer in two unconfined dimensions has remained a challenge owing to the difficulty of creating electrostatic barriers that are sharp on the order of the electron wavelength(7). Here, we report the observation of conductance oscillations in extremely narrow graphene heterostructures where a resonant cavity is formed between two electrostatically created bipolar junctions. Analysis of the oscillations confirms that p-n junctions have a collimating effect on ballistically transmitted carriers(8). The phase shift observed in the conductance fringes at low magnetic fields is a signature of the perfect transmission of carriers normally incident on the junctions(9) and thus constitutes a direct experimental observation of 'Klein tunnelling'(10-12).