Multilayer Al2O3—SiO2combination (MASC) films as a partial H2diffusion barrier for use on Ge surfaces

Multilayer Al2O3-SiO2combination (MASC) films are shown to be superior to SiO2films for Ge surface passivation during a forming-gas annealing cycle. The Al2O3is apparently much less permeable to H2than is SiO2. Hydrogen easily permeates SiO2, producing a high density of surface acceptor states on the Ge. Even in the absence of hydrogen exposure, the surface-state and fixed-charge densities under MASC films are reduced by a factor of 2 or more as compared to pyrolytic SiO2films.