Molecular-beam epitaxy of MnAs on patterned GaAs substrates

Abstract

MnAs were grown on (001) GaAs substrates with mesa-grooves along the [110] and [110] directions having outward sloping sidewalls and inward sloping sidewalls, respectively, by molecular-beam epitaxy with/without the supply of hydrogen radicals (H·). The epilayer shapes have been investigated using secondary electron microscope observations after growth. The vertical film thickness on the (001) surface is irrespective of the rotation of substrates during growth. On the other hand, the lateral film thickness on the sidewall decreased as the Mn flux was decreased. The shapes of MnAs layers were independent on the supply of H·, although the irradiation of H· improves the surface smoothness. These results indicate that the surface-diffusion length of Mn adatoms is small. Consequently, by adjustment of the direction of Mn flux, MnAs layers can be selectively grown on the one side of the sidewalls of patterned substrates.