Boron surfactant enhanced growth of thin Si films on CaF2∕Si

Boron surfactant enhanced solid-phase epitaxy (SPE) of thin Si films on CaF2∕Si(111) substrates has been studied. Two different growth processes were investigated. In the first process, 1ML of boron atoms was predeposited on the CaF2 surface at room temperature before Si evaporation followed by an anneal to 635°C. This resulted in Si cluster formation. The surface morphology of the Si layer did not show any improvement compared to SPE without surfactant. In the second process, boron atoms were deposited directly on top of the amorphous Si film. This resulted in continuous and smooth epitaxial Si layers on CaF2 with a sharp B-induced (3×3)R30° surface reconstruction after annealing.