Capping III–V compound surfaces with Ge ultra-thin layer might be a viable pathway to passivate the electrically active interface traps which usually jeopardize the integration of III–V materials in metal-oxide-semiconductor devices. As the physical nature of such traps is intrinsically related to the chemical details of the interface composition, the structural and compositional features of the Ge/GaAs interface were thoroughly investigated in two different configurations, the atomic layer deposition of La-doped ZrO2 films on Ge-capped GaAs and the ultra-high vacuum based molecular beam deposition of GeO2/Ge double stack on in situ prepared GaAs. In the former case, the intercalation of a Ge interface layer is shown to suppress the concentration of interface Ga–O, As–O and elemental As bonding which were significantly detected in case of the direct oxide deposition on GaAs. In the latter case, the incidence of two …