AES Study of Growth Process of Al Thin Films on Uranium Dioxide

Metallic uranium was exposed to 40 languirs of oxygen at room temperature in order to form UO₂ on the surface of metallic U. And thin layers of aluminum on UO₂ were prepared by sputter deposition under ultra high vacuum conditions. Process of Al thin film growth and its interaction with UO₂ were investigated by auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS). It was shown that the Al thin film growth underwent via the VolmerWeber (VW) mode. At room temperature, Al and UO₂ interact with each other, electrons transfer occurres from Al atoms to uranium ions, and a few of Al₂O₃ exist in the region of UO₂/Al interface due to O₂ adsorption to the surface. Interdiffusion between UO₂ and Al is observable. Aluminum diffuses into interface region of UO₂ and U. It results in the formation of a coexistence regime containing uranium oxide, metallic U and Al.