Deposition of stoichiometric Bi$_{2}$Se$_{3}$ film by vacuum-thermal treatment of Se/Bi heterostructure

The possibility of obtaining a stoichiometric Bi$_{2}$Se$_{3}$ film by vacuum-thermal treatment of a Se/Bi heterostructure is demonstrated for the first time. It was found that a stoichiometric Bi$_{2}$Se$_{3}$ film can be only produced at a certain ratio of the Se and Bi film thicknesses ($d_{\mathrm{Se}}/d_{\mathrm{Bi}}$ = 3.13). X-ray-diffraction analysis and Raman spectroscopy were used to study the phase transformations in a Se(141 nm)/Bi(45 nm) heterostructure upon its thermal treatment in a vacuum. The phase transition temperatures at which various crystalline phases are formed were determined. It is shown that Bi$_{2}$Se$_{3}$ crystallizes in the Se(141 nm)/Bi(45 nm) heterostructure heated to 493 K in conformity with an exponential law, with a characteristic time in which the equilibrium state is attained equal to 20 min.