Radiation Effects in Thin-Film Ferroelectric PZT for Non-Volatile Memory Applications in Microelectronics

Radiation effects on switching kinetics of three-dimensional ferroelectric capacitor arrays

“…This means that photogenerated charges are more likely trapped at the interfaces with electrodes, the trapping location depending upon the charge sign, the direction of applied bias, and the local polarization of domains. 5 This feature is in agreement with the interface screening scenario proposed by Grossmann et al and explains the enhancement of voltage shift under external bias or UV illumination. 14 A good trapping condition for charged defects is fulfilled at the interface between a dielectric surface layer and the undisturbed ferroelectric film.…”

“…Both observations may be interpreted in considering the trapping of photoinduced charges: ͑i͒ at the ferroelectric film/ electrode interfaces, with subsequent asymmetric trapped charge distribution which screens the polarization state and leads to voltage shift and ͑ii͒ in the bulk of the ferroelectric film at defect levels, with subsequent domain wall pinning explaining the polarization reduction. [3][4][5][6] This latter interpretation is in agreement with the appearance of "frozen" regions in the ferroelectric film. 11,12 Indeed, the polarization reduction observed on hysteresis loops corresponds to a progressive widening of switching current peak during irradiation.…”

“…3,4 Indeed, in ferroelectric materials x-ray or ␥-ray irradiation produces electron-hole pairs which undergo the influence of the local field in the different domains. 5,6 Even in the absence of external field, the strong local field ensures a violent separation of photoinduced charges which are subsequently trapped at lattice point defects, stoichiometric defects, or grain boundaries. The free electronic charges may also be attracted to charged domain wall regions where there is a discontinuity in polarization.…”

“…The direction of irradiation-induced voltage shift is determined by the sign of the remnant polarization before exposure. [3][4][5][6] After each hysteresis loop measurement, the capacitors are poled in a positive remnant polarization state P R + and this poling results in a loop shifting towards negative voltages. 3 Furthermore, the voltage shift is accompanied by a drastic polarization reduction of about 30% after 17 h of exposure ͓Fig.…”

Impact of radiations on the electromechanical properties of materials and on the piezoresistive and capacitive transduction mechanisms used in microsystems

“…7the post-irradiation capacitance versus voltage ferroelectric loops which have been obtained from three different samples after 10 kGy γ dose are presented. C-V characteristics of the irradiated capacitors show no change compared to non irradiated ones in common with findings reported in Ref 45. and the same applies to samples that have received lower doses of γ radiation which are not presented here.…”