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

Abstract

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 ̄ 1 0 0] direction for the hexagonal MnAs epilayer grown with H ·, and along both the [ 1 ̄ 1 0 0] and [ 1 ̄ 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 ̄ 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.