Advancement of Topological Nanostructures for Various Applications

Topological materials are characterized by a unique band topology that is prominently distinct from ordinary metals and insulators. This new type of quantum material exhibits insulating bulk and conducting surface states that are robust against time-reversal invariant perturbations. In 2009, Bi2Se3 , Sb2Te3 and Bi2Te3 were predicted as 3D Topological insulators (TIs) with a single Dirac cone at the surface state. For application purposes, however, bulk conductivity due to Se vacancy in Bi2Se3 or antisite defects in Bi2Te3 has been a challenging issue. In order to achieve an enhanced surface conductivity over the bulk, nanomaterials are irreplaceable. Nanostructures' high surface to volume ratio provides a good platform for investigating the topological existence of surface states. By tuning the position of Fermi level through field effect gating, it is also possible to terminate the bulk residual carriers. Moreover, the synthesis of nanomaterials allows for morphological, electronic, and chemical regulation, resulting in the ability to design structures with desired TI properties at the nanoscale. In this article, we review various technological applications of nanostructured topological insulators. We also survey the implementation of topological nanomaterials in the field of optoelectronic devices, p-n junction, superconducting materials, field effect transistor, memory device and spintronics, ultrafast photodetection, and quantum computations. 

Keywords: Band topology, Dirac cone, Quantum computations, Quantum material, Topological nanostructure.