Effect of Sintering Parameter on the Microstructure and Electrical Properties for Bi2Se3 Topological Insulator Crystals

Single crystals of Bi2Se3 topological insulators have been prepared though melt-grown reaction. The sintering parameters of holding time and cooling rate obviously affect the phase structure and electrical properties. The samples with layered structure can be perpendicular cleaved with (0 0 L) axis. All the samples show n-type conductivity caused by the existence of Se vacancies. For low cooling rate, more Se atoms anti-occupy Bi lattice sites, which decreases c-axis lattice parameter and increases carrier concentration n; high cooling rate increases c and decreases n because of less Se atoms occupying Bi lattice sites. Increasing holding time firstly decreases the ratio of Se atoms occupying Bi lattice sites and then increases it, which gives rise to c firstly increase then decrease and n firstly decrease then increase.