Oxidation Mechanism and Surface Passivation of Germanium by Ozone

Oxidation mechanism and passivation of Ge surface by ozone is experimentally investigated. The GeOx oxidation process contains two regions: initial linear growth region and following parabolic growth region. The linear growth region contains reaction of oxygen atoms with surface bond and back bonds of outmost Ge layer. The parabolic growth region starts when the oxygen atoms diffuse into back bonds of second outmost Ge layers. Furthermore, in the ozone oxidation it is not O3 molecules but O radicals that go through the GeOx film. The interface state density (Dit) is found to decrease with increasing the GeOx thickness (0.26-1.06 nm). X-ray photoelectron spectroscopy (XPS) results show that Ge3+ oxide component is responsible to the decrease of D-it.