The dramatic enhancement of the silicon room-temperature oxidation rate by a Na overlayer has been attributed to the spectator catalytic action of the alkali metal. In contrast, we show evidence that Na participates in the oxidation process binding an oxygen atom in a substoichiometric intermediate oxidation state. This causes preferential saturation of the semiconductor dangling bonds on the surface and a subsequent promotion of the oxide growth. We have, in fact, detected the Na 2p photoemission chemical shifts when bonds with an oxygen atom are established in a hybrid configuration.
Giovanni De Cesare, Sylvain Dunand, Jonathan Emanuel Thomet, Mikaël Martino, Luca Massimiliano Antognini, Matthew James Large
Patrik Willi Hoffmann, Lucas Güniat, Marc Leparoux
Raffaella Buonsanti, Anna Loiudice, Krishna Kumar, Ona Segura Lecina, Petru Pasquale Albertini, Philippe Benjamin Green, Coline Marie Agathe Boulanger, Jari Leemans, Mark Adrian Newton