Multilayer films composed of alternating layers of Bi and Se-[Bi(4.55 Å)/Se(6.82 Å)] n (Bi4Se6), [Bi(6.13 Å)/Se(12.26) Å] n (Bi6Se12), and [Bi(4.86 Å)/Se(18.46 Å)] n (Bi4Se18)-were fabricated by controlling the layer thickness at the atomic scale using thermal evaporation techniques. After annealing treatment, the Bi4Se18 alternately layered film shows a single phase of Bi 2Se 3 rhombohedral crystalline structure with the characteristic density of single crystal Bi 2Se 3, whereas the Bi6Se12 and Bi4Se6 films show locally disordered Bi 2Se 3 crystalline structure. The effectively controlled layered structure in the as-grown Bi4Se18 film enhances the Bi-Se chemical bonding state. The formation of a layered crystalline structure during the annealing process increased as the thickness of Se increased. After interdiffusion and the crystallization process, alternately layered Bi4Se18 films become stable Bi 2Se 3 single crystals with a continuous and uniform layered structure. Finally, in the Bi-Se system, atomically controlled multilayers with an optimized ratio of each unit layer can be transformed to a perfect single-crystalline structure on oxidized Si with an amorphous phase through a self-organized ordering process.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films