Atomically-thin crystalline films and ribbons of bismuth telluride

摘要

The authors report on "graphene-like" exfoliation of the large-area crystalline films and ribbons of bismuth telluride with the thicknesses of a few atoms. It is demonstrated that Bi_2Te_3 crystal can be mechanically separated into its building blocks-Te-Bi-Te-Bi-Te atomic fivefolds-with the thickness of ～ 1 nm and even further-to subunits with smaller thicknesses. The atomically-thin films can be structured into suspended crystalline ribbons providing quantum confinement in two dimensions. The quasi two-dimensional crystals of bismuth telluride revealed high electrical conductivity and low thermal conductivity. The proposed atomic-layer engineering of bismuth telluride opens up a principally new route for drastic enhancement of the thermoelectric figure of merit.