SURFACTANT-INDUCED REVERSIBLE CHANGES OF SURFACE-MORPHOLOGY

We have investigated the influence of a surfactant on the equilibrium surface morphology in the pseudomorphic regime of heteroepitaxial grow th. At 700-degrees-C, 8 monolayers of Ge on Si(001) using Sb as surfac tant form strained islands with a size of approximately 300 angstrom, allowing partial elastic relaxation. The surface morphology depends st rongly on the Sb coverage and changes from islands with [117] facets a t high Sb coverage via round, flat cones with an inclination angle of 12-degrees to islands rotated by 45-degrees with [105] facets formed d uring growth at low Sb coverage. The equilibrium conditions are verifi ed by the reversible transition from [117] facets to 12-degrees cones initiated by a change of the surfactant coverage.