Exploring the Surface Chemical Reactivity of Single Crystals of Binary and Ternary Bismuth Chalcogenides

Abstract

The chemical reactivity of single crystals of binary and ternary bismuth chalcogenides toward oxygen, water, and carbon monoxide has been investigated by X-ray photoemission spectroscopy by using synchrotron radiation. We find that single crystals of Bi 2 Se 3 are inert toward oxygen in the temperature range 300−550 K. The protection against surface oxidation at high temperature is important for preserving the thermoelectric efficiency in applications for power generation. By contrast, water adsorbs at room temperature on Bi 2 Se 3 . Finally, we find a different reactivity toward carbon monoxide in PbBi 6 Te 10 at room temperature with respect to other bismuth chalcogenides.

Interplay of Surface and Dirac Plasmons in Topological Insulators: The Case ofBi2Se3

“…The chemical inertness of our Bi 2 Se 3 samples [19] prevents the appearance of contamination-induced 2DEG states reported previously [35][36][37]. However, we would like to point out that no additional plasmonic mode would exist even in samples exhibiting 2DEG states because of their energy position at the bottom of the bulk conduction band.…”

“…Fresh surfaces were readily made available for HREELS measurements by cleaving the crystal along its natural cleavage plane. Such single crystals are also chemically inert [19,20].…”

Mechanical properties of Bi2Te3 topological insulator investigated by density functional theory and nanoindentation

“…The temperature of the "cold" zone was about 100 K lower than the melting point. The grown ingot consisted of one or several large single crystalline blocks, which show chemical inertness toward surface oxidation for even one month in air, as shown elsewhere [18]. Fresh surfaces were readily available by cleaving the crystals along their natural cleavage plane, to obtain (0001)-oriented surfaces.…”

“…By analyzing core levels in XPS spectra [18], the absence of surface oxide phases even after having exposed samples to large doses of oxygen or even after air exposure can be claimed. As a matter of fact, the amount of defects in single-crystal samples used in this investigation is minimized so that the oxidation rate, driven just by surface defects [13], is negligible even after months in air, contrarily to previous reports for bismuth chalcogenides [14,38].…”

“…The optimized use of the Bridgman-Stockbarger method in vacuum/inert atmosphere can strongly reduce the amount of vacancies in TI samples [17]. This implies chemical inertness toward surface oxidation [17][18][19]. Moreover, such a notable control on growth methods allows tuning the position of the Fermi level [20] or even the position of the Dirac point [21], thus paving the way for band-structure engineering of TI heterostructures [22].…”