ANOMALY IN THE GROWTH-RATE OF ANODIC OXIDE-FILMS DUE TO THE PRESENCE OF A (SM+SM2O3) OVERLAYER AT A GAAS SURFACE

To our knowledge, no experiments on plasma anodic oxidation of heavily doped GaAs, assisted by very thin samarium overlayers, have been repo rted up to now. The following interesting results are obtained from th e investigation of a Sm-based oxide/GaAs structure: (i) a rapid increa se of the oxide growth rate; (ii) a possibility of important changes o f the electronic properties of the interface, especially suppression o f the high-temperature part of the charge deep level transient spectra ; (iii) an appreciable distortion of the subsurface bulk crystal latti ce of the anodized semiconductor. A sketch of the oxide growth mechani sm is presented. We have attempted to prove that before the oxidation process itself the Ga and As atoms diffuse into the (Sm + Sm2O3) overl ayer and a rare-earth compound is formed.