Role of surface energy and surface reconstructions on the 2D-to-3D growth-mode transition of strained InxGa1-xAs layers on InP(001)

We show that the role played by surface energy in the total-energy balance between the initial two-dimensional (2D) state and the final three-dimensional (3D) state is of prime importance to explain morphologies observed during the molecular-beam epitaxy growth of strained materials. This was established by analyzing differences in 2D-3D transition onsets for 2% mismatched InxGa1-xAs films grown on InP(001) substrates when changing the mismatch sign (compression or tension), the film doping, and the type of surface stabilization (anion or cation). The 2D-3D onsets were measured by reflection high-energy electron diffraction and the corresponding surface morphologies characterized by scanning tunneling microscopy.