Microstructure investigations and structure-property correlations in ferroelectric thin-film capacitors

Epitaxial 0%, 3% and 10% La doped PZT capacitors with a LSCO bottom electrode grown by pulsed laser deposition on Si using a Ti(Al)N/Pt conducting barrier layer were systematically studied. Ferroelectric capacitors substituted with 10% La show a significantly lower coercive voltage compared to capacitors with 0% and 3% La. This is attributed to the systematic variation of the domain structure of the PLZT film with the increase of La concentration. The in-plane orientation relationship of this heterostructure is: [110]PLZT//[110]LSCO//[110]Pt// [110]Ti(Al)N//[110]Si. The morphology of the domains as a function of La concentration was studied using high resolution transmission electron microscopy(HREM). The Pt/Ti(Al)N conducting barrier layer stack is intact after the deposition of the LSCO/PLZT/LSCO stack. All Ti(Al)N layers in the samples studied consist of column-like structures with a [110] texture.