Smooth p-type GaAs(001) films grown by molecular-beam epitaxy using silicon as the dopant

Atomic force microscopy, Hall effect and photoluminescence measurements were used to investigate the morphological, electrical and optical properties of GaAs(001):Si films obtained by droplet-assisted molecular-beam epitaxy using a peculiar shutter sequence for the delivery of the silicon, gallium and arsenic species. Although silicon is almost exclusively used as a n-type dopant on GaAs(001) substrates, with such growth conditions a p-type character of the GaAs:Si layers was generally detected. The best morphological results were obtained when a single monolayer of gallium and arsenic were alternately deposited and the dopant was evaporated during the gallium cycle, since in that special case no gallium droplets were formed on the substrate, minimizing thus the total roughness of the final surface.