Kinetics of MnAs growth on GaAs(001) and interface structure

On different As-rich GaAs(001) templates, well characterized by reflectance difference spectroscopy, nucleation and growth of NiAs-type MnAs is investigated in real time by reflection high-energy electron diffraction. Using very high ${\mathrm{As}}_{\mathrm{4}}\mathrm{/Mn}$ flux ratios and low growth rates, one of the two occurring azimuthal alignments of the $\text{(1̄100)}$ orientation can be nearly suppressed even in the nucleation stage, and it vanishes completely with further growth. Annealing is found to be very effective in surface smoothing. In dependence on the As/Mn ratio the $\mathrm{MnAs}\text{(1̄100)}$ surface develops different reconstructions. This finding is important for further investigations in the growth of double heterostructures. High-resolution transmission electron microscopy of as-grown MnAs/GaAs samples reveals an abrupt interface. The lattice mismatch accommodation is anisotropic with regularly arranged misfit dislocations along the $\text{[1̄10]}$ direction and less localized coherency strain in the [110] direction, consistent with a near-coincidence-site lattice model.