Influence of contact electrodes on leakage characteristics in ferroelectric thin films

Electrodes can impact the device performance of ferroelectric capacitors in several ways. The present controlled studies on $\mathrm{Pb}\mathrm{\hspace{0.5em}(}{\mathrm{Nb, Zr, Ti)O}}_{\mathrm{3}}$ with Pt, $({\mathrm{La, Sr)CoO}}_{\mathrm{3}}$ and ${\mathrm{SrRuO}}_{\mathrm{3}}$ is a clear demonstration of the role of electrodes in impacting the leakage current mechanism of the ferroelectric capacitors and their reliability properties. The oxide electrode capacitors show predominantly nonblocking contact and good fatigue and imprint properties. Pt electrode capacitors show blocking contacts, long term leakage current relaxation, and poor fatigue and imprint properties. The nature of the temperature and voltage dependence of leakage current relaxation in Pt capacitors indicates trapping of charge carriers to be the cause for the observed relaxation. A good correlation between leakage current relaxation and the rate of polarization loss during fatigue and the similarity in their voltage and temperature dependence suggests trapping (of charged carriers/domains, respectively) as common to both phenomena.