For a Ge(111) surface irradiated by an electron beam of 1.5‐keV energy and current density of 2 &mgr;A mm−2, it was found that beam‐assisted oxygen adsorption at pressures <10−9Torr always resulted in carbon‐contaminated overlayers and was probably due to dissociation of physisorbed CO. The sticking coefficientsof CO was 0.08. At oxygen pressures ≳10−6Torr, carbon‐free coverages could be formed, even without irradiation.sfor oxygen was 6×10−4for beam‐assisted and 1.5×10−4for nonassisted adsorption. Electron impact desorption followed a first‐order rate equation and the desorption cross section for oxygen was 6×10−20cm2.