STABILITY OF THE DIMER STRUCTURE FORMED ON SI(100) BY ULTRACLEAN LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION

Stability against air exposure of the dimer structure formed on Si(100 ) by ultraclean low-pressure chemical-vapor deposition was investigate d. A 2 X 1-reconstructed dimer structure was clearly observed on the e pitaxial Si film on Si(100) by reflection high-energy electron diffrac tion even after air exposure for 180 min. The dissociation process of the dimer structure and the oxidation process in the air depended on t he cooling atmosphere in the reactor after chemical-vapor deposition a s well as on the humidity of the air. It is proposed that the dissocia tion of the dimer structure in the air is suppressed by hydrogen adsor ption and coincides with the oxidation of H-terminated or dangling bon ds due to H2O adsorption.