Solid-phase reactions and phase transformations in a nanoscale bismuth/selenium film structure

Experimental results of a study concerned with solid-phase reactions and phase transformations in a Bi/Se nanoscale film structure under heat treatment in vacuum are presented. Nanocrystalline Bi$_{2}$Se$_{3}$, BiSe, and Bi$_{4}$Se$_{3}$ films are obtained for the first time by solid-phase synthesis at various ratios between the Bi and Se layer thicknesses. The phase-transformation temperatures at which Se, BiSe, and Bi4Se3 crystalline phases are formed are determined. The average crystallite sizes in the Bi$_{2}$Se$_{3}$, BiSe, and Bi$_{4}$Se$_{3}$ films are found to be 21, 23, and 33 nm, respectively.