Metalorganic vapor phase epitaxy of ternary rhombohedral (Bi1−xSbx)2(Bi1−xSbx)2 Se3 solid solutions

• Epitaxial (Bi2Se3)(Bi2Se3) films were grown on the sapphire substrate by MOVPE at 460 °C.
• Rhombohedral and orthorhombic films of (Bi1−xSbx)2Se3(Bi1−xSbx)2Se3 were deposited at 480 °C.
• Rhombohedral (Bi4Se3)(Bi4Se3) and Bi phases were obtained at lower temperatures.
• Characterization of the films was carried out by Raman, XRD, AFM, SEM and EDS techniques.

We studied the metalorganic vapor phase epitaxy (MOVPE) of (Bi1−xSbx)2Se3(Bi1−xSbx)2Se3 solid solution films with a different Sb content on (001) Al2O3 substrates with thin ZnSe buffer layer in the range of temperatures 250–480 °C. As-grown films were studied by atom force and scanning electron microscopy (AFM and SEM), Raman spectroscopy and X-ray diffractometry (XRD) techniques. To determine the elemental composition of the grown films, we used an energy dispersive spectrometer (EDS). The dependencies of the crystal structure of films on the growth temperature and Sb content (0≤x≤10≤x≤1) were explored. At different growth temperatures we obtained the following bismuth compounds: the films grown at the temperature of 370 °C or lower consist of the pure Bi phase, whereas we got the Bi4Se3 phase at 380 °C, the phase BiSe at 430 °C and Bi2Se3 at the temperature of 460 °C or above. We found out that at the temperature of 480 °C the single-phase films of (Bi1−xSbx)2Se3(Bi1−xSbx)2Se3 with rhombohedral and orthorhombic lattices are realized when x   is less than 0.25 and greater than 0.935, respectively. For 0.25