Experimental and first-principles study of defect structure of topological insulator Bi2Se3 single crystal

High quality single crystal of Bi2Se3 was grown using a modified Bridgman technique. Their phase structures, electrical transport properties and defects were studied. The results of X-ray diffraction and High-resolution transmission electron microscopy showed that the as-obtained bulk Bi2Se3 crystal has layered structure with (0 0 L) planes being aligned along one direction. Both the measurement of component and the electrical transport showed that the sample has Se vacancies. First-principles calculations showed that the vacancy point defects on the Se1 atom and antisite defect BiSe1 (substitute one Se1 atom by Bi atom) are realistic.