Stable and Metastable InGaAs/GaAs Island Shapes and Surfactantlike Suppression of the Wetting Transformation

Contrasting behaviors are observed in $\mathrm{InGaAs}/\mathrm{GaAs}$ island formation during vapor phase epitaxy: variation of group V partial pressures gives different critical thicknesses for the onset of the Stranski-Krastanow transformation, surface coverages, ratios between coherent and incoherent islands, and dissimilar morphologies upon annealing. The latter experiments show that small lens-shaped islands can be found in equilibrium if InGaAs surface energies are minimized, leading to the conclusion that ${\mathrm{AsH}}_3$ can raise surface energies and act as an impurity-free “morphactant.”