Realization of Tellurene – a 2D Tellurium Allotrope
Two-dimensional (2D) materials, in which atoms are arranged in a single layer, are of significant interest for electronic, optoelectronic, and sensor applications. One of the critical hurdles for many 2D systems is the ability to synthesize, isolate, and stabilize these low-dimensional systems, as exemplified by the case of graphene. The availability of large-scale, high-quality graphene triggered an explosive amount of research into this and other 2D materials. Stanene, i.e. 2D Sn, was recently synthesized and joined graphene, silicene and germanene in the group-IV monolayer materials, as were group III and V borophene and phospherene. In contrast, group VI elements have yet to be stabilized in purely 2D forms. Here, we show the first realization of a 2D chalcogen, namely tellurene – a 2D tellurium allotrope. We have successfully produced tellurene using a wafer-bonding assisted self-assembly process, a new approach to synthesize and stabilize low-dimensional structures. Atomic-resolution chemical mapping and structural characterization via scanning transmission electron microscopy (STEM) leading to the definitive identification of tellurene. First principles calculations found tellurene to be metallic in character, with electronic band structures containing Dirac-cone-like features, and exhibiting significant asymmetric spin-orbit band splitting. The underlying electronic structure rearrangement of the monolayer is evidenced by its plasmonic resonance, as measured by electron energy-loss spectroscopy. These findings enable further research into suitability of tellurene for device applications, such as spintronics and quantum computing. If wafer-bonding-assisted synthesis is proven feasible beyond tellurene, our approach could open possibilities to synthesis of atomic-structures which may otherwise be highly challenging to produce using conventional deposition techniques.