LAUSR

Abstract The structural change of InAs(001) wetting layer (WL) surface from c(4×4) to (2×4) surfaces is theoretically investigated by using ab initio-based approach incorporating temperature and beam equivalent pressure. The calculations of surface phase diagrams demonstrate that adsorption and desorption of In and As atoms occur on the c(4×4) surface with two In-As and As-As dimers at 703 K, resulting in the formation of the c(4×4) surface with InAs coverage θ = 1.13 monolayer (ML). For θ = 1.13 ML, it is also found that the total energy of the (2×4) surface, whose constituent atoms are same as those of the c(4×4) surface, is lower than that of the c(4×4) surface. This is because the number of excess electrons on the (2×4) surface is smaller than that on the c(4×4) surface. Furthermore, the adsorption of two In atoms and desorption of one As atom per unit cell occurs on the (2×4) surface, resulting in the formation of the (2×4)α2 surface. These calculated results suggest that the formation of the c(4×4) surface is of importance to understand the formation of (2×4)α2 InAs WL surface grown on the GaAs(001) substrate.