By engineering the composition of a chalcogenide heterostructure, researchers from CAMP-Nano explored the existence of crystalline GeTe2, a compound unknown in the bulk, for the first time. This work was accepted by Nanoscale on 22 Mar 2018.

The recently discovered two-dimensional (2D) group IV chalcogenides attract much attention owing to their novel electronic and photonic properties. All reported materials of this class favor (distorted) octahedral coordination via p bonding; by contrast, in the dichalcogenides where the bonding tendency approaches sp3, no corresponding 2D phase has been realized so far. In this work, by engineering the composition of a chalcogenide heterostructure, the hitherto elusive GeTe2 is experimentally observed in a confined 2D environment. Density functional theory simulations predict the existence of a freestanding monolayer of octahedrally coordinated GeTe2 under tensile strain, a synthesis strategy is also proposed to form other unconventional 2D materials, such as octahedrally bonded 2D GeSe2 and GeS2. These 2D germanium dichalcogenides are either metallic or narrow gap semiconducting, and may lead to new applications in nanoscale electronics.

This research is supported by National Natural Science Foundation of China (61774123 and 51621063), the Youth Thousand Talents Program of China and the Young Talent Support Plan of Xi'an Jiaotong University.

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