Enhanced Electrical Resistivity and Properties via Ion Bombardment of Ferroelectric Thin Films.

Author(s): Saremi, S; Xu, R; Dedon, LR; Mundy, JA; Hsu, SL; Chen, Z; Damodaran, AR; Chapman, SP; Evans, JT; Martin, LW | Abstract: 140 nm PbTiO3/20 nm SrRuO3thin-film heterostructures were grown on SrTiO3(001) single-crystal substrates via pulsed-laser deposition. In order to study the properties of these films, symmetric SrRuO3capacitor structures were fabricated using established techniques and dramatic differences were observed in the leakage characteristics of the heterostructures. The high-pressure O2and O2/Ar heterostructures reveal more than 2 orders of magnitude higher leakage current densities as compared to the low-pressure O2 heterostructures. In turn, the high leakage current density of the heterostructures grown in high pressures precludes measurement of closed, saturated ferroelectric hysteresis loops, while nearly-square, fully saturated and closed hysteresis loops can be measured for the low-pressure O2heterostructures. The defects responsible for poor transport and ferroelectric properties in PbTiO3thin films are identified to be isolated point defects such as Pb3+centers and lead vacancies, which contribute to hole conduction. Introduction of bombardment-induced defects is shown to be an effective way to quench these trap states by turning them into deep lying defect complexes and clusters which, in turn, leads to a dramatic reduction of leakage current by up to 5 orders of magnitude and improvement of ferroelectric device performance.