Two-dimensional (2D) crystals are known to have no bulk but only surfaces and edges, thus leading to unprecedented properties thanks to the quantum confinements. For half a century, the compression of z -dimension has been attempted through ultra-thin films by such as molecular beam epitaxy. However, the revisiting of thin films becomes popular again, in another fashion of the isolation of freestanding 2D layers out of van der Waals (vdW) bulk compounds. To date, nearly two decades after the nativity of the great graphene venture, researchers are still fascinated about flattening, into the atomic limit, all kinds of crystals, whether or not they are vdW. In this introductive review, we will summarize some recent experimental progresses on 2D electronic systems, and briefly discuss their revolutionizing capabilities for the implementation of future nanostructures and nanoelectronics.

中文翻译：

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扁平化越来越讨人喜欢：革命性的2D电子系统

众所周知，二维（2D）晶体没有体积，只有表面和边缘，因此由于量子限制，导致了前所未有的性能。半个世纪以来，已经尝试通过诸如分子束外延的超薄膜来压缩z维。但是，薄膜的再造再次流行起来，这是将独立的2D层与范德华（vdW）块状化合物隔离的另一种方式。迄今为止，在巨大的石墨烯企业诞生后近二十年，研究人员仍然着迷于将各种晶体（无论是否为vdW）展平到原子极限。在这篇介绍性综述中，我们将总结2D电子系统的一些最新实验进展，