Molecular-beam epitaxy of MnAs in the presence of atomic hydrogen

Effects of atomic hydrogen (H-.) on the molecular-beam epitaxy of MnAs/GaAs heterostructures were investigated. X-ray diffraction and reflection high-energy electron diffraction characterizations revealed that the growth was along the [(1) over bar 1 0 0] direction for the hexagonal MnAs epilayer grown with H-., and along both the [(1) over bar 1 0 0] and [(1) over bar 1 0 1] directions for the epilayers grown with/without hydrogen molecules (H-2). Atomic force microscope (AFM) images showed that the faceted mounds elongated along the GaAs[1 1 0] direction were only observed for the epilayers grown with H-.. On the other hand, large three-dimensional (3D) islands were observed on the elongations along the GaAs[(1) over bar 1 0] direction for the epilayers grown with/without the supply of H-2. The results indicate that the irradiation of H-. enhances the growth of MnAs epilayers along the single direction and improves the surface smoothness. (C) 1998 Elsevier Science B.V. All rights reserved.