Secondary electron imaging of nucleation and growth of GaAs

Abstract

In situ scanning electron microscopy was used for real-time imaging of surface morphology evolution during molecular beam epitaxial growth of GaAs. This method is characterized by a resolution that is high enough to resolve nucleated islands, and a high sensitivity to atomic layers. Electron-beam damage was avoided by reducing the primary beam current to 0.1–0.3 nA. Different growth stages, i.e. nucleation delay, nucleation of islands, coalescence of islands and monolayer completion, are clearly imaged during monolayer growth. The surface roughens with increases in the nucleation-coalescence cycle, and recovers its initial smoothness during post-growth annealing.