THE OBSERVATION OF MONOLAYER AND BILAYER GROWTH DURING THE DEPOSITIONOF GAAS(110) FILMS BY MOLECULAR-BEAM EPITAXY

The growth of GaAs(110) films by molecular beam epitaxy (MBE) has been investigated in-situ using reflection high energy electron diffractio n (RHEED). By careful choice of growth conditions, films with smooth s urface morphology have been obtained and RHEED oscillations indicating two-dimensional growth by monolayer steps have been observed. At low growth temperatures and more arsenic rich conditions, RHEED oscillatio ns with twice the period are observed, which suggests that under these conditions growth is occurring by the formation of islands with doubl e layer steps. The dependence of the transition between the two growth modes on the growth conditions and arsenic flux suggests that reconst ruction at step edges, which stabilises double layer steps at the lowe r temperature, may be responsible.