Electron trapping process in ferroelectric lead–zirconate–titanate thin-film capacitors

The effects of constant voltage stress on ferroelectric lead–zirconate–titanate (PZT) thin-film capacitors have been studied. Two stress effects are observed in the PZT capacitance–voltage (C–V) characteristics. The first is that the capacitance is reduced, and the second is a voltage shift of the C–V curve. These effects are found to depend on the stress electric field and the injected charge fluence. A correlation between the stress effects and the electron trapping inside the films is established. The injected charge fluence can be calculated from the leakage current. The trapping efficiency, electron capture cross section, and the trap density are obtained from the measured injected charge influence and the C–V voltage shift. The calculated value of the electron capture cross-section σT is 1.89×10−19 cm2 and the neutral electron trap density NT is 1.20×1013 cm−2.