Ba0.8Sr0.2TiO3 ferroelectric nanofilms on silicon buffered with a TiO2 layer

Abstract

Polycrystalline, 50- to 70-nm-thick barium strontium titanate films of composition Ba0.8Sr0.2TiO3 have been grown on single-crystal silicon substrates by rf ion-beam sputtering. We have determined their structure and composition and detected impurities at the film/substrate interface in the form of titanium silicide islands. The deposition of a 4- to 6-nm-thick TiO2 buffer layer onto Si by ion-beam sputtering before ferroelectric film growth is shown to prevent uncontrolled formation of impurities near the interface. The buffered heterostructures possess high thermal stability.