Search

HfO2-based ferroelectric materials as the most promising candidate for the ferroelectric memories, have been widely studied for more than a decade due to their excellent ferroelectric properties and CMOS compatibility. In order to realize its industrialization as soon as possible, researchers have been devoted to improving the reliability performance, such as wake up, imprint, limited endurance, et al. Among them, the breakdown characteristic is one of main failure mechanisms of HfO2-based ferroelectric devices, which limits the write/read reliability of the devices. Based on this, we systematically studied the effect of thickness on the time-dependent dielectric breakdown (TDDB) tolerate capability of HfO2–ZrO2 (HZO) FE films under both forward and reverse electrical stress conditions. The thickness of HZO FE film ranged from 6 to 20 nm. Our findings reveal that decreasing the thickness of the HZO FE film leads to an improvement in TDDB tolerance capability which is attributed to the fact that higher density of oxygen vacancies in thinner HZO FE films can effectively inhibit the generation of new oxygen vacancies and the growth of conductive filaments, thus effectively improving the TDDB characteristics. These results provide a potential solution for mitigating breakdown characteristics of HfO2-based ferroelectric devices in memory applications. [ABSTRACT FROM AUTHOR]

Structural monitoring is crucial for assessing structural health, and high-precision deformation prediction can provide early warnings for safety monitoring. To address the issue of low prediction accuracy caused by the non-stationary and nonlinear characteristics of deformation sequences, this paper proposes a similarity clustering (SC) deformation prediction model based on GNSS/accelerometer time-frequency analysis. First, the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) algorithm is used to decompose the original monitoring data, and the time-frequency characteristic correlations of the deformation data are established. Then, similarity clustering is conducted for the monitoring sub-sequences based on their frequency domain characteristics, and clustered sequences are combined subsequently. Finally, the Long Short-Term Memory (LSTM) model is used to separately predict GNSS displacement and acceleration with clustered time series, and the overall deformation displacement is reconstructed based on the predicted GNSS displacement and acceleration-derived displacement. A shake table simulation experiment was conducted to validate the feasibility and performance of the proposed CEEMDAN-SC-LSTM model. A duration of 5 s displacement prediction is analyzed after 153 s of monitoring data training. The results demonstrate that the root mean square error (RMSE) of predicted displacement is 0.011 m with the proposed model, which achieves an improvement of 64.45% and 61.51% in comparison to the CEEMDAN-LSTM and LSTM models, respectively. The acceleration predictions also show an improvement of 96.49% and 95.58%, respectively, the RMSE of the predicted acceleration-reconstructed displacement is less than 1 mm, with a reconstruction similarity of over 99%. The overall displacement reconstruction similarity can reach over 95%. [ABSTRACT FROM AUTHOR]

HfO 2 -based ferroelectric materials as the most promising candidate for the ferroelectric memories, have been widely studied for more than a decade due to their excellent ferroelectric properties and CMOS compatibility. In order to realize its industrialization as soon as possible, researchers have been devoted to improving the reliability performance, such as wake up, imprint, limited endurance, et al. Among them, the breakdown characteristic is one of main failure mechanisms of HfO 2 -based ferroelectric devices, which limits the write/read reliability of the devices. Based on this, we systematically studied the effect of thickness on the time-dependent dielectric breakdown (TDDB) tolerate capability of HfO 2 -ZrO 2 (HZO) FE films under both forward and reverse electrical stress conditions. The thickness of HZO FE film ranged from 6 to 20 nm. Our findings reveal that decreasing the thickness of the HZO FE film leads to an improvement in TDDB tolerance capability which is attributed to the fact that higher density of oxygen vacancies in thinner HZO FE films can effectively inhibit the generation of new oxygen vacancies and the growth of conductive filaments, thus effectively improving the TDDB characteristics. These results provide a potential solution for mitigating breakdown characteristics of HfO 2 -based ferroelectric devices in memory applications., (© 2024 IOP Publishing Ltd.)