Nonstoichiometric doping and Bi antisite defect in single crystal Bi2Se3

TL;DR

This study investigates how different defects, specifically Bi_Se antisite and Bi intercalation, influence the growth, structure, and electrical properties of Bi2Se3 crystals, revealing defect origins and effects.

Contribution

It identifies and characterizes key defects in Bi2Se3 crystals using advanced microscopy and spectroscopy, linking defect types to growth conditions and properties.

Findings

Bi_Se antisite and Bi intercalation are major defects.

Defects significantly affect lattice size and transport properties.

A unified explanation for defect origin and growth behavior.

Abstract

We studied the defects of Bi2Se3 generated from Bridgman growth of stoichiometric and nonstoichiometric self-fluxes. Growth habit, lattice size, and transport properties are strongly affected by the types of defect generated. Major defect types of Bi_Se antisite and partial Bi_2-layer intercalation are identified through combined studies of direct atomic-scale imaging with scanning transmission electron microscopy (STEM) in conjunction with energy-dispersive X-ray spectroscopy (STEM-EDX), X-ray diffraction, and Hall effect measurements. We propose a consistent explanation to the origin of defect type, growth morphology, and transport property.