Plasma oxidation of thin polycrystalline aluminum films (∼100 Å) on GaAs has shown that oxidation of aluminum proceeds by an initial rapid grain-boundary oxidation of the aluminum followed by a slower oxidation towards the centers of the individual grains. Continued oxidation results in the growth of Ga-As- oxide layers on both sides of the Al-oxide film indicating that the oxidation of GaAs proceeds by an electric-field-assisted in-migration of oxygen through the Al-oxide layer toward the interface and the out-migration of Ga and As toward the surface. This oxidation process can be used to form an amorphous film of Al-oxide on GaAs. By using the Al-oxide film as a preferential filter for the migration of Ga and As, an amorphous Ga-As-oxide film with a Ga/As concentration ratio of unity all the way to the GaAs substrate can also be achieved.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)