Interaction of Ce overlayers with the GaSb 111/surface and oxidation of the CerGaSb interface

In this paper we use XPS to study the interaction of Ce overlayers with the semiconductor GaSb 111. surface and Ce-promoted oxidation of the substrate. The results show that when cerium deposits on GaSb 111., it forms weak bonds of Ce–Ga and Ce–Sb with the substrate and makes Ga atoms diffuse out. A Ce–Ga intermetallic phase is formed on the surface. When the exposure of O2reaches 50 L, the oxide of cerium, Ce2O3, begins to change into unstable CeO2. The dissociation of CeO2 results in obvious oxidation of the substrate. The main products are Ga2O3, Sb2O3 and then Sb2O5. After annealing at 250 and 4008C, respectively, some of the oxygen atoms transfer from cerium dioxide toward Ga and Sb in the substrate, by which it strongly promotes the oxidation of the substrate. q1997 Elsevier Science B.V.