FORMATION OF AMORPHOUS INTERLAYERS IN ULTRAHIGH-VACUUM DEPOSITED YTTRIUM THIN-FILMS ON (111)SI

Formation of amorphous interlayers (a interlayers) has been observed in the interfacial reactions of ultrahigh vacuum deposited yttrium thin films on atomically clean (111)Si at low temperatures. The observation of the a interlayer in the Y/Si system represents the first report of solid-state amorphization for rare-earth metal/Si systems. The Y/Si system is also the only system found to date among all metal/Si systems in which the a interlayer can be grown to a thickness exceeding 10 nm during deposition at,room temperature. A process involving significant diffusion of both Y and Si atoms is proposed to account for the dependence of amorphization on the thickness of deposited yttrium films.