Paper MI-MoA9
Identifying the Intrinsic Atomic Defects in Bi₂Se₃ with Scanning Tunneling Microscopy

Monday, November 10, 2014, 4:40 pm, Room 311

In topological insulators the helical Dirac fermions are immune to backscattering as long as the time reversal symmetry is preserved. However, the existence of intrinsic atomic defects in materials such as Bi₂Se₃ and Bi₂Te₃ still represents one of the major issues for applications. Intrinsic atomic defects such as vacancies or antisites not only could dope charges, make the insulators conductive and shift the Dirac electrons away from the fermi energy but also affect the mobility of the materials by introducing disorder. By studying a series of Bi₂Se₃ samples that were grown with different conditions with atomic resolving scanning tunneling microscopy, we have successfully identified several types of intrinsic defects, including Se vacancies and Bi-Se antisites. The densities of these different types of defects could be correlated with growth conditions and the total density is related to the band shift measured by tunneling spectroscopy. Our study demonstrates the capability of scanning tunneling microscopy in diagnosing materials like Bi₂Se₃ and similar ones at the atomic level.