Rates and total amounts of the arsenic for antimony exchange reaction on the GaSb (001) surface are measured via line-of-sight mass spectrometry during molecular beam epitaxial growth. On the Sb-terminated GaSb (001) surface, an As for Sb exchange is observed to occur at all levels of incident As-2 flux studied. By contrast, on the surface with one monolayer of Ga, there exists a critical As-2 flux below which the As for Sb exchange is suppressed, and a two-dimensional (2D) surface morphology is maintained. Above the critical As-2 flux, the As for Sb exchange is observed to be linear with increasing As-2 flux. Substrate temperatures above 470 degrees C and As-2 fluxes greater than 1 x 10(-6) Ton beam flux pressure lead to a drastic increase in As/Sb exchange accompanied by the occurrence of 3D surface morphology. As/Sb exchange at the interfaces of InAs/GaSb type-II superlattices leads to a reduced average lattice constant of the superlattices and degrades interface quality, as determined by x-ray diffraction.