LMGP Séminaire interne : Catherine DUBOURDIEU-31 mars 2015 - Monolithic integration of complex oxides on semiconductors by MBE

Directeur de Recherche
Institut des Nanotechnologies de Lyon


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. Studies in this field were boosted by the search in the early 2000’s for ultrathin crystalline high permittivity oxides in order to replace the conventional SiO2-based gate oxide in advanced field-effect transistors. 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 talk, I will review the challenges associated with the monolithic integration of complex oxides on a semiconductor and more particularly with the integration of ferroelectrics. I will present a study on BaTiO3 films epitaxially grown on Si(001) and SiGe by MBE. Ferroelectricity – with reversible switching of the polarization - is evidenced by piezoresponse force microscopy with polarization pointing perpendicular to the silicon substrate. The nano-domain structure is discussed on the basis of geometrical phase analysis of HRTEM images. Size effects on the ferroelectricity of BaTiO3 ultrathin films and nanostructures are addressed.

I will conclude with two perspectives. One deals with in situ coupling MBE and CVD/ALD techniques for developing new oxide growth routes. Another one deals with the integration of epitaxial ferroelectric oxides in low power logic devices.

Infos lieu
3:00 pm - salle de séminaires - 2nd étage