Study of pulsed laser deposited lead lanthanum titanate thin films

Abstract

Paraelectric lanthanum doped lead titanate (PLT) thin films for high permittivity material applications were grown on Pt-coated Si-substrates by the laser ablation technique. A rapid thermal annealing (RTA) process was adopted to induce crystallization and a polycrystalline fine microstructure was obtained. The dielectric properties, capacitance-voltage (C-V) characteristics and polarization hysteresis (P-E) with temperature were studied. The dielectric constant was approximately 720 while the dissipation factor was approximately 0.04 at room temperature for a 0.9-µ m thick film at 100 kHz frequency. Hysteresis behavior was observed in C-V and P-E responses and was attributed to the presence of charge accumulation either in the grain boundaries or in the electrode-film interface. The charge storage density aspect was studied for DRAM applications and the obtained charge storage density at 6 V was 4.5 µ C/cm². The density of surface charge states was approximately 10¹³ cm²/eV at room temperature and the effect of temperature and frequency was studied and correlated with the properties of the film.