Indium-induced smoothing of GaAs films during MBE growth

Abstract

A new technique is reported for obtaining a smooth growth surface during molecular beam epitaxy growth of GaAs on (001) GaAs substrates. The smoothing is achieved by exposing the surface to an indium flux during growth of the GaAs buffer layer at high substrate temperature (590 °C). In situ light scattering shows a dramatic reduction in surface roughness along the [110] direction during this process, consistent with ex situ scanning force microscopy measurements on the films, which reveal atomically flat terraces oriented along the <110> directions. The surface reconstruction shifts from (2 × 4) to (4 × 2) under the indium flux, as revealed by reflection high-energy electron diffraction. The sticking coefficient of the indium as determined by secondary-ion mass spectroscopy is less than 10%. We attribute the observed effects to a transition from group V to group III termination, induced by surface segregation of the nonincorporated indium.