In-situ growth of Pb(Zr0.5Ti0.5)O-3/RuO2 heterostructures on Si(001) using low-temperature metal-organic chemical vapor deposition

Pb(Zr0.5Ti0.5)O-3/RuO2 thin film heterostructures were successfully grown on SiO2/Si(001) substrates using metal-organic chemical vapor deposition with a maximum processing temperature of 525 degrees C. To form the heterostructures, (110)-textured RuO2 electrode layers were first deposited on SiO2/Si(001) substrates at temperatures as low as 350 degrees C at a typical grow rate of similar to 40 Angstrom/min.. The resistivity of the RuO2 films was 30-40 mu Omega-cm. Plan-view transmission electron microscopy (TEM) and atomic force microscopy (AFM) showed that typical RuO2 films had a grain size of 800-1000 Angstrom with surface roughness of 3-25 nm, respectively. Perovskite phase Pb(Zr0.5Ti0.5)O-3 (PZT) was then deposited at 525 degrees C. The as-deposited films exhibited a dense, randomly-oriented crystal structure with a grain size of similar to 800-1000 Angstrom. Using capacitors defined with Ag top electrodes, the film showed a remanent polarization of 21.5 mu C/cm(2) and a coercive field of 39.0 kV/cm. The capacitors showed little fatigue up to similar to 10(10) cycles. The as-deposited films exhibited high resistivity (10(12)-10(13) Omega-cm at 100 kV/cm). The current versus voltage characteristics show that the films have typical dielectric breakdown strengths of similar to 60 V/mu m with a sub-breakdown leakage current density of 5 x 10(-5) A/cm(2).