Direct observation of band bending in topological insulator Bi2Se3

TL;DR

This study directly measures the band bending in Bi2Se3 topological insulators using hard x-ray photo spectroscopy, revealing the depth and magnitude of surface-bulk electronic structure variations.

Contribution

It provides the first direct measurement of band bending depth and amplitude in Bi2Se3 using bulk-sensitive HAXPES, confirming previous indirect estimates.

Findings

Band bending extends up to about 20 nm into the bulk.

Amplitude of band bending is approximately 0.23--0.26 eV.

Results are consistent with prior surface state energy profiles.

Abstract

The surface band bending tunes considerably the surface band structures and transport properties in topological insulators. We present a direct measurement of the band bending on the Bi2Se3 by using the bulk sensitive angular-resolved hard x-ray photospectroscopy (HAXPES). We tracked the depth dependence of the energy shift of Bi and Se core states. We estimate that the band bending extends up to about 20 nm into the bulk with an amplitude of 0.23--0.26 eV, consistent with profiles previously deduced from the binding energies of surface states in this material.