Ab initio-based approach to novel behavior in semiconductor hetero-epitaxial growth

Novel behavior in semiconductor hetero-epitaxial growth such as InAs/GaAs is systematically investigated using ab initio-based approach incorporating temperature T and beam equivalent pressure p. The calculated In adsorption-desorption boundary curve elucidates that In atoms can adsorb on the InAs(1 1 1)A-(2 × 2) with In-vacancy wetting layer (WL) surface with simultaneous As adsorption similarly to homo-epitaxial growth. On the InAs(0 0 1)-(2×4)α2 WL surface, however, In atoms hardly adsorb on the (0 0 1) WL in contrast with In adsorption on homo-epitaxial surface without strain. These results suggest that strain accumulated in the WL is not significant for the hetero-epitaxial growth on the InAs(1 1 1)A but strongly affects the growth process on the InAs(0 0 1) at the initial growth stage. It is also found that the InAs(0 0 1)-(2 × 3) WL surface fully covered by As dimers is unstable while the (n × 3) surfaces (n = 4, 6, and 8) with (n − 1) dimers and one missing dimer is more stable at the conventional molecular beam epitaxial growth conditions. It should be noted that In atoms are incorporated through In-As dimer formation with As desorption below InAs coverage θ ∼ 0.9 monolayer (ML) on the (n × 3) surfaces. This suggests that the growth dose not proceed at θ > 0.9 ML without strain relaxation on the InAs/GaAs(0 0 1).