Coverage dependence of migration potential of cation adatoms on GaAs(001)-(2 × 4) surface

Abstract

We theoretically investigate the migration potential of cation adatoms on the reconstructed As-rich GaAs (001)-(2 × 4) surface by ab initio calculation. By increasing the number of cation adatoms, we also study how migration potential depends on coverage. The calculated results for Ga adatoms suggest that the long-bridge sites are energetically the most favorable at the initial stage of crystal growth. However, as the Ga coverage increases, the missing dimer row sites become the most favorable. Migration potentials strongly depend on the adatom coverage. Similar results were obtained for A1 adatom migration. Furthermore, based on these migration potentials, we demonstrate the dynamical behavior of cation adatoms on GaAs(001) surface by performing Monte-Carlo simulations at finite temperatures.