The surface reconstructions and migration behavior on InAs(001) and InAs(111)A wetting layer on GaAs substrate are systematically investigated by our ab initio-based approach and Monte Carlo simulations. The ab initio-based approach incorporates the chemical potentials of In atom and As-4 molecule in the gas phase as functions of temperature T and beam equivalent pressure p(As4). The calculated surface phase diagrams imply that the respective stable surface structures of InAs(001) and InAs(111)A are the (2 x 4)alpha 2 and the In-vacancy surfaces at conventional growth conditions at T similar to 700-750 K and P-As4 similar to 10(-7)-10(-6) Torr. On these surfaces, adsorption-desorption boundary for In atom appears below the growth temperatures. Therefore, In adatoms tend to desorb from the InAs(001) and the InAs(111)A surfaces at equilibrium. Kinetic behavior of In adatoms obtained by the Monte Carlo simulations reveal that life time tau and diffusion length L of In adatoms are small such as tau = 1.59 x 10(-3) s and L = 618 nm on the InAs(001) and tau = 4.35 x 10 (14) s and L = 0.204 nm on the InAs(111)A. On the basis of these results, the growth process on the InAs(111)A is discussed in terms of self-surfactant effect where simultaneous As adsorption makes In atom adsorb on the surface. (c) 2012 Elsevier B.V. All rights reserved.