Multilayer Al2O3—SiO2combination (MASC) films as a partial H2diffusion 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.