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

Abstract

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 O 2 reaches 50 L, the oxide of cerium, Ce 2O 3, begins to change into unstable CeO 2. The dissociation of CeO 2 results in obvious oxidation of the substrate. The main products are Ga 2O 3, Sb 2O 3 and then Sb 2O 5. After annealing at 250 and 400°C, 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.