Multilayer Al 2 O 3 —SiO 2 combination (MASC) films as a partial H 2 diffusion barrier for use on Ge surfaces

Multilayer Al 2 O 3 -SiO 2 combination (MASC) films are shown to be superior to SiO 2 films for Ge surface passivation during a forming-gas annealing cycle. The Al 2 O 3 is apparently much less permeable to H 2 than is SiO 2 . Hydrogen easily permeates SiO 2 , 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 SiO 2 films.