Metallic conduction through van der Waals interfaces in ultrathin Bi2Te3 films

While the van der Waals (vdW) interface in layered materials hinders the transport of charge carriers in the vertical direction, it serves a good horizontal conduction path. We have investigated electrical conduction of few quintuple-layer (QL) Bi2Te3 films by in situ four-point probe conductivity measurement. The impact of the vdW (Te-Te) interface appeared as a large conductivity increase with increasing thickness from 1 to 2 QL. Angle-resolved photoelectron spectroscopy and first-principles calculations reveal the confinement of bulk-like conduction band (CB) state into the vdW interface. Our analysis based on the Boltzmann equation showed that the conduction of the CB has a long mean free path compared to the surface-state conduction. This is mainly attributed to the spatial separation of the CB electrons and the donor defects located at the Bi sites.

Automated summary

The study revealed that the vdW interface in Bi2Te3 films can lead to a significant increase in conductivity with increasing thickness due to the confinement of conduction band states at the interface.