Single Domain Bi$_{2}$Se$_{3}$ Films Grown on InP(111)A by Molecular-Beam Epitaxy

We report the growth of single domain Bi$_{2}$Se$_{3}$(111) thin films by MBE on InP(111) substrate. On singular and vicinal substrate surfaces, we observe the 2D growth mode, as implied by the streaky RHEED patterns and the RHEED intensity oscillations. In the 2D step-flow growth mode, the epitaxial Bi$_{2}$Se$_{3}$ film is found to be diminished of twin and rotation domains, as inferable from both the unidirectional mounds seen by STM and by the three-fold LEED patterns. Such films show relatively low background doping ($\sim$ 1 $\times$ 10$^{18}$ cm$^{-3})$ and high low-temperature electron mobility (3500 cm$^{2}$V$^{\mathrm{-1}}$s$^{-1})$. Magnetoresistance measurements unveil SdH oscillations at different sample tilting angles. Ab initio total energy calculations suggest the existence of strong chemical interaction between atoms at the hetero-interface. Therefore, the growth does not proceed by the vdW epitaxy process. The additional chemical interaction between P and Bi atoms at steps would facilitate step-flow mode of growth, making the steps to offer an effective guide to the lattice of epitaxial Bi$_{2}$Se$_{3}$.