Dr. Catherine Dubourdieu - Monolithic integration of ferroelectric oxides on semiconductors: BaTiO3 polarization switching on silicon

Abstract

The ability to epitaxially grow the perovskite compound SrTiO₃ on Si by molecular beam epitaxy (MBE) opened up the route, 15 years ago, to the monolithic integration of functional oxides on a semiconductor platform. MBE provides unique advantages to precisely construct, almost atom by atom, the oxide/semiconductor interface. Interface engineering using Sr- or Ti-based passivation is employed for the epitaxial growth of SrTiO₃ templates on Si or GaAs substrates respectively. These templates are subsequently used to grow perovskite complex oxides, which offer a wide range of properties, such as piezoelectricity, pyroelectricity, ferroelectricity, magnetism, multiferroicity or specific electro-optic properties.

In this presentation, I will review the work performed at IBM Yorktown Heights (in collaboration with the University of Texas Austin and Oak Ridge National Laboratory) and at the Institut des Nanotechnologies de Lyon on the growth and characterization of BaTiO₃ epitaxial films on SrTiO₃-buffered silicon in view of their integration onto field-effet transistors (FET) for low power device applications. Ferroelectricity was evidenced by piezoforce microscopy with polarization pointing perpendicular to the silicon substrate for BaTiO₃ films on silicon without a conducting bottom electrode (MOS structures) and in a thickness range of 8-40 nm. Nanoscale characterization of the crystalline domains structure will be discussed based on GPA analyses of STEM images. I will conclude with perspectives on device integration, particularly in gate-last damascene FETs.