Abstract

The development of graphene has demonstrated the possibility of preparing, characterizing, and utilizing crystals with a thickness of just one or a few monolayers. The study of graphene revealed not only the attractive mechanical properties of such atomically thin materials, but also the emergence of distinctive electronic and optical properties in the two-dimensional limit that are not shared by the bulk counterpart of the material. During the past few years, the community has recognized that atomically thin two-dimensional crystals can be prepared using a much broader class of materials than carbon, including the preparation of new insulators (such as hexagonal BN) and new semiconductors. In this paper, we focus on our growing understanding of the properties of a new class of two-dimensional semiconductors in the transition metal dichalcogenide family. In particular, we will consider materials of the form MX₂, with transition metal M = Mo, W and chalcogen atom X = S, Se, Te. These materials, semiconductors in the bulk, have now been prepared and investigated in the limit of single and few-layer crystals. The materials share the attractive mechanical properties of graphene, including flexibility and stability under high levels of strain, but they offer very different electrical and optical properties.

© 2015 IEEE