Molecular beam epitaxial growth of InAs on a (311)A corrugated surface: Growth mechanism and morphology

Abstract

Kinetic molecular beam epitaxy growth processes and the structure of the InAs (311)A surface were investigated in situ by reflection high energy electron diffraction (RHEED) and ex situ by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). Two stable surface structures, (2×15) and (1×5), were observed by RHEED on as-grown surfaces. RHEED oscillations have a strong azimuthal anisotropy with maximum amplitude in the [2̄33] direction and minimum amplitude in the [011̄] direction, suggesting that this surface grows via propagation and coalescence of pronounced two dimensional nuclei along the [2̄33] azimuth. Ex situ LEED and STM studies of the As-capped InAs (311)A surfaces confirmed the strong anisotropy of the surface structure. A characteristic feature of the LEED patterns is the degeneration of the principal diffraction into streaks along the [011̄] direction. STM images show rows running along the [2̄33] direction. Although the spacing between the rows varies, there are local areas showing lateral periodicities of ∼2.15 nm [(1×5) structure] and ∼6.45 nm [(2×15) structure] along the [011̄] direction, consistent with RHEED observations.