School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.
Nat Commun. 2013;4:1794. doi: 10.1038/ncomms2817.
The chemical stability of graphene and other free-standing two-dimensional crystals means that they can be stacked in different combinations to produce a new class of functional materials, designed for specific device applications. Here we report resonant tunnelling of Dirac fermions through a boron nitride barrier, a few atomic layers thick, sandwiched between two graphene electrodes. The resonance occurs when the electronic spectra of the two electrodes are aligned. The resulting negative differential conductance in the device characteristics persists up to room temperature and is gate voltage-tuneable due to graphene's unique Dirac-like spectrum. Although conventional resonant tunnelling devices comprising a quantum well sandwiched between two tunnel barriers are tens of nanometres thick, the tunnelling carriers in our devices cross only a few atomic layers, offering the prospect of ultra-fast transit times. This feature, combined with the multi-valued form of the device characteristics, has potential for applications in high-frequency and logic devices.
石墨烯和其他独立二维晶体的化学稳定性意味着它们可以以不同的组合堆叠，从而产生一类新的功能性材料，专门针对特定的器件应用而设计。在这里，我们报告了狄拉克费米子通过硼氮层间的共振隧穿，该硼氮层厚几原子层，夹在两个石墨烯电极之间。当两个电极的电子谱对齐时，就会发生共振。该器件特性中的负微分电导在室温下持续存在，并且由于石墨烯独特的类狄拉克谱，可以通过栅极电压进行调节。尽管传统的共振隧穿器件包括夹在两个隧道势垒之间的量子阱，厚度为数十纳米，但我们的器件中的隧穿载流子仅穿过几个原子层，从而提供了超快速传输时间的可能性。这种特性，加上器件特性的多值形式，在高频和逻辑器件中有潜在的应用。
