TdC20. High speed opto-electronic non-destructive readout prom ferroelectric thin film capacitors

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Abstract
Polarization dependent photoresponse from ferroelectric lead zirconate titanate (PbZr0. 53Ti0. 47O3) thin films sandwiched between metal electrodes in a capacitor configuration is reported. This phenomenon has potential application as a non-destructive readout(NDRO) of nonvolatile polarization state of thin film ferroelectric memories. High speed readout using laser pulses with full width at half maximum of ∼10ns, at 532 nm wavelength is demonstrated. The polarization direction of the ferroelectric capacitor is reflected in the direction of the photocurrent response. The rise time of the photocurrent response is as fast as 25 ns and the relaxation time is fraction of a microsecond. The readout signal from individual polarized elements is repeated over a million times with no detectable degradation in the photoresponse or the remanent polarization as verified independently by the conventional destructive readout technique. In principle, both electronic as well as thermal mechanisms could be triggered by such photon exposure of ferroelectric thin films. Comparison of the photoresponses from a device with a semitransparent top electrode and an opaque top electrode respectively suggests that the observed NDRO signal is predominantly due to thermally triggered mechanisms.