Stability of terbium scandate on Si(100)

We have examined the stability of TbScO3 on Si(100) using medium energy ion scattering. At high temperatures the dielectric decomposes into a Tb-rich silicate layer near the substrate, and a Sc-rich layer near the surface. Interfacial SiO2 is consumed in the reaction. We find that Sc 2 O3 by itself does not react with SiO2 while Tb2 O3 readily forms a silicate. This difference in reactivity drives the vertical separation of metal ions. Consideration of the fundamental chemistry of rare-earth scandates suggests that rare-earth scandates are unstable in the presence of SiO2 © 2010 American Institute of Physics.