The review concerns the most interesting aspects of (mainly experimental) resonance tunnelling spectroscopy studies of a new type of heterosystems called van der Waals heterostructures. The possibility to compose such systems is a result of the recent discovery of two-dimensional crystals, a new class of materials derived from graphene. The role of the angular mismatch of the crystal lattices of conductive graphene electrodes in the tunnelling of charge carriers between them, as well as the closely related issues associated with fulfillment of the conservation laws during tunnelling transitions are considered. The experimental results on inelastic tunnelling in the graphene/h-BN/graphene heterosystems with strong angular mismatch are discussed. The experiments made it possible to determine the phonon density of states spectra of the constituent layers and to detect and describe tunnelling transitions involving localized states of structural defects in the h-BN barrier. We consider new results of studies on tunnelling and magnetotunnelling in van der Waals heterosystems that demonstrate the possibilities of practical application of resonant tunnelling effects in, e.g., microwave engineering, based on realization of electronic devices having I – V curves with negative differential conductance (NDC) regions at tunnelling through defect levels of the barrier layers in such systems. These studies revealed two new types of heterosystems characterized by the formation of NDC regions as a result of resonant tunnelling through the defect levels in the h-BN barrier and by defect-assisted generation of tunnelling current.The bibliography includes 40 references.

中文翻译：

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范德华异质系统的共振隧穿光谱

该评论涉及对一种称为范德华异质结构的新型异质系统的（主要是实验性的）共振隧道光谱研究中最有趣的方面。构成此类系统的可能性是最近发现的二维晶体的结果，二维晶体是一种源自石墨烯的新型材料。考虑了导电石墨烯电极晶格的角失配在它们之间的电荷载流子隧穿中的作用，以及在隧穿过渡期间与满足守恒定律相关的密切相关问题。讨论了具有强角失配的石墨烯/h-BN/石墨烯异质体系中非弹性隧穿的实验结果。这些实验使得确定组成层的声子态谱密度和检测和描述涉及 h-BN 势垒中结构缺陷的局部状态的隧道跃迁成为可能。我们考虑了范德瓦尔斯异质系统中隧道和磁隧道研究的新结果，这些结果证明了谐振隧道效应在例如微波工程中实际应用的可能性，基于实现具有负微分电导 (NDC) 的 I-V 曲线的电子设备) 隧道穿过这种系统中势垒层的缺陷水平的区域。