Tuning the Dirac point position in Bi(2)Se(3)(0001) via surface carbon doping

Area of Science:

• Condensed Matter Physics
• Materials Science
• Surface Science

Background:

• Topological insulators (TIs) possess unique surface states with potential for novel electronic applications.
• Bismuth selenide (Bi_{2}Se_{3}) is a prominent TI material, but precise control over its surface electronic properties remains challenging.
• Understanding surface modifications is crucial for harnessing TI functionalities.

Purpose of the Study:

• To investigate the effects of trace carbon doping on the surface electronic structure of Bi_{2}Se_{3}.
• To explore the relationship between surface structural modifications and electronic property changes.
• To identify new methods for tuning the surface band structure of topological insulators.

Main Methods:

• Angular resolved photoemission spectroscopy (ARPES) was employed to probe the electronic band structure.
• Ab initio calculations were performed to complement experimental findings and understand electronic behavior.
• Surface X-ray diffraction (SXRD) was utilized to characterize surface structural changes.

Main Results:

• Trace carbon doping controllably shifted the Dirac point within the bulk band gap of Bi_{2}Se_{3}.
• Contrary to expectations, no Rashba-split two-dimensional electron gas states were observed.
• Surface structural analysis revealed an approximately 11% expansion of the top Se-Bi spacing, correlating with the electronic modifications.

Conclusions:

• Carbon doping offers a novel route to precisely tune the surface band structure of topological insulators like Bi_{2}Se_{3}.
• The observed electronic modifications are intrinsically linked to carbon-induced surface structural reconstructions.
• These findings open new avenues for designing and fabricating advanced electronic devices based on topological materials.