2015 Volume 13 Pages 190-194
The structural change in InAs(001)-(2×3) wetting layer surfaces grown on GaAs is investigated using ab initio-based approach incorporating temperature T and beam equivalent pressure p. Our calculated results reveal that the (2×3) surface fully covered by As dimers is unstable while the (n×3) surfaces (n =4, 6, and 8) with (n −1) dimers including In-As and one missing dimer is more stable at the conventional molecular beam epitaxial (MBE) growth conditions such as T = 703 K under pIn = 1:0×10-7 Torr and pAs4 = 7:5×10-7 Torr. On the (n×3) surfaces, In atoms are incorporated through In-As dimer formation with As desorption. The resultant (4×3) surface consists of three In-As dimers and one missing dimer. The (6×3) surface has three In-As dimers, two As dimers, and one missing dimer. Only one In-As dimer emerges with six As dimers and one missing dimer on the (8×3) surface. The missing dimer region becomes favorable site for further In adsorption. Moreover, the (8×3) can easily change to the (4×3) with In adsorption and subsequent As dimer desorption on the initial (8×3). The existence ratio R for the (4×3) and (6×3) units is respectively estimated to be R = 0:70 and 0.30 satisfying 0.375 ML desorption of As on the (2×3) to form the (2×4)α2. This is consistent with experimental results. Consequently, the (n×3) surfaces including In-As dimers appear during MBE growth instead of the (2×3) surface with As-dimers. [DOI: 10.1380/ejssnt.2015.190]
