Monolayer oscillations of the Sb desorption rate during molecular beam epitaxy of GaSb

•First observation of Sb desorption oscillations in-situ during MBE growth of GaSb.•Sb desorption oscillations observed to correlate with layer-by-layer growth.•Correlation with specular RHEED oscillations uncovers relationship with step density.•Discovery that Sb desorption oscillations persist during growth of GaInSb alloys. In-situ desorption mass spectrometry (DMS) tool is used to report monolayer oscillations of the Sb desorption rate during molecular beam epitaxy (MBE) growth of GaSb and GaInSb. Oscillations in the Sb desorption rate appear to be correlated to the variation in the surface-step-density that periodically changes the additional uptake and expulsion of Sb beyond the fixed rate of consumption. This notion is corroborated by comparing the Sb DMS signal to the time derivative of the specular RHEED beam intensity.