Chemical interaction at the Tm/Si(111) interface

Abstract

Interface investigations of Tm/Si(111) have been carried out using XPS, UPS and glancing incidence XRD at various temperatures. Room temperature interface evolution takes place in three stages. Initially there is no reaction between adsorbate and substrate and Tm clusters are formed. In the second regime cluster coalescence takes place and there is a strong interaction between Tm and Si to form TmSi₂. Finally, metal-rich Tm₅Si₃ phase formation takes place. High-temperature studies reveal that at 473 K, predominantly the Tm₅Si₃ phase is present with some TmSi₂, while the film is completely converted into a disilicide phase by annealing at 673 K. Binding energies of Si 2p corresponding to various Tm silicides are identified. At all temperatures, throughout the interface development, Tm was found to be trivalent in nature.