Band structure of Bi surfaces formed on Bi2Se3 upon exposure to air

TL;DR

This study investigates the electronic band structure of bismuth surfaces formed on Bi2Se3 after air exposure, revealing that these surfaces dominate photoemission signals and impact surface-sensitive measurements.

Contribution

It provides the first detailed band structure measurements of Bi surfaces on Bi2Se3 after air exposure, highlighting their significance in electronic properties and experimental analysis.

Findings

Bi surfaces dominate photoemission signals after air exposure

Band structure of Bi surfaces resembles a single bilayer of Bi

Air exposure should be minimized in surface-sensitive experiments

Abstract

Bi$_2$Se$_3$ has been the focus of intense interest over the past decade due to its topological properties. Bi surfaces are known to form on Bi$_2$Se$_3$ upon exposure to atmosphere, but their electronic structure has not been investigated. We report band structure measurements of such Bi surfaces using angle-resolved photoemission spectroscopy. Measured spectra can be well explained by the band structure of a single bilayer of Bi on Bi$_2$Se$_3$, and show that Bi surfaces consistently dominate the photoemission signal for air exposure times of at least 1 hour. These results demonstrate that atmospheric effects should be taken into consideration when identifying two-dimensional transport channels, and when designing surface-sensitive measurements of Bi$_2$Se$_3$, ideally limiting air exposure to no more than a few minutes.