Metastable deexcitation spectroscopy (MDS) was applied to the study of
the growth of the Yb/GaAs(110) interface. MD spectra taken at differe
nt coverages, from 0.04 ML to 30 ML, revealed the progressive metalliz
ation of the overlayer. Absence of 4f emission allowed to observe, for
the first time, VB features of the forming interface up to similar to
8 ML.