Epitaxical La[sub(0.5)]Sr[sub(0.5)]CoO[sub(3)] Electrode Films for Ferroelectric Device Applications

Most ferroelectric devices are configured as a capacitor in which a layer of ferro­ electric material is sandwiched between a pair of electrodes. The quality of the bottom electrode dictates the structural and electrical properties of the remaining part of the heterostructure. The top electrode has a less direct effect. Nevertheless, the quality of its interface with the ferroelectric layer might be expected to have a significant impact on the device fatigue characteristics. Taking these factors into consideration, electrode material should be chemically inert, electrically conductive and, most importantly, structurally matched to the ferroelectric material to mini­ mize interfacial defect formation. Thus far, the most common choice has been Pt. For electro-optical devices, transparent electrodes such as Ru0 2 and Indium Tin Oxide (ITO) are used. The properties of these electrodes are less than ideal because they are not structurally compatible with the ferroelectric material. Consequently, there is always a high density of point defects such as misfit dislocations and oxygen vacancies at the interface. Such defects are believed to be the sources of device performance fatigue due to oxygen vacancy migration and to the repetitive pi­ ezoelectric distortion.