Search Results (8)

This work experimentally investigated the wake-up behaviors of hafnium oxide-based ferroelectric capacitors by manipulating the interval time between each characterization cycle. Both Positive-Up–Negative-Down (PUND) and Negative-Down–Positive-Up (NDPU) waveforms were used as the stress and measurement waveforms in the experiments. It was found that the imprint occurs as the total interval time increases to a several-seconds level. However, this only affects the remnant polarization (P_R) of ferroelectric capacitors when stressed by NDPU waveforms, since the voltage amplitude saturates under the PUND stress conditions and does not influence the P_R. The wake-up behavior has been proved to be caused by the defects redistribution during electrical cycling. Notably, when using PUND waveforms, the change in the interval time can result in different increase rates of P_R, indicating the possibility of recovery during the intervals. This recovery leads to a slower wake-up when cycling with a longer interval time. Moreover, it is observed that this P_R recovery could reach saturation after several seconds of the interval time. This comprehensive investigation of wake-up and imprint behaviors can provide new insights to evaluate and enhance the reliability of ferroelectric memories. Full article

In this work, 10 nm scandium-doped aluminum nitride (AlScN) capacitors are demonstrated for the construction of the selector-free memory array application. The 10 nm Al_0.7Sc_0.3N film deposited on an 8-inch silicon wafer with sputtering technology exhibits a large remnant polarization exceeding 100 µC/cm² and a tight distribution of the coercive field, which is characterized by the positive-up-negative-down (PUND) method. As a result, the devices with lateral dimension of only 1.5 μm show a large memory window of over 250% and a low power consumption of ~40 pJ while maintaining a low disturbance rate of <2%. Additionally, the devices demonstrate stable multistate memory characteristics with a dedicated operation scheme. The back-end-of-line (BEOL)-compatible fabrication process, along with all these device performances, shows the potential of AlScN-based capacitors for the implementation of the high-density selector-free memory array. Full article

Punding is a rare condition triggered by dopaminergic therapy in Parkinson’s disease (PD), characterized by a complex, excessive, repetitive, and purposeless abnormal movement, and its pathogenesis remains unclear. We aimed to assess the brain structure alterations related to punding by using multipametric magnetic resonance imaging (MRI). Thirty-eight PD patients (19 with punding and 19 without punding) from the Parkinson’s Progression Marker Initiative (PPMI) were included in this study. Cortical thickness was assessed with FreeSurfer, and the integrity of white matter fiber tracts and network topologies were analyzed by using FMRIB Software Library (FSL) and Pipeline for Analyzing braiN Diffusion imAges (PANDA). PD patients with punding showed a higher apathy score and more severe cortical atrophy in the left superior parietal, right inferior parietal, and right superior frontal gyrus, and worse integrity of the right cingulum cingulate tract compared to those without punding. On the other hand, no significant difference in structural network topologies was detected between the two groups. These data suggest that the specific area of destruction may be an MRI biomarker of punding risk, and these findings may have important implications for understanding the neural mechanisms of punding in PD. Full article

In the past decade, aluminum scandium nitride (AlScN) with a high Sc content has shown ferroelectric properties, which provides a new option for CMOS-process-compatible ferroelectric memory, sensors and actuators, as well as tunable devices. In this paper, the ferroelectric properties of $A{l}_{0.7}S{c}_{0.3}N$ grown on different metals were studied. The effect of metal and abnormal orientation grains (AOGs) on ferroelectric properties was observed. A coercive field of approximately 3 MV/cm and a large remanent polarization of more than 100 μC/cm² were exhibited on the Pt surface. The $A{l}_{0.7}S{c}_{0.3}N$ thin film grown on the Mo metal surface exhibited a large leakage current. We analyzed the leakage current of $A{l}_{0.7}S{c}_{0.3}N$ during polarization with the polarization frequency, and found that the $A{l}_{0.7}S{c}_{0.3}N$ films grown on either Pt or Mo surfaces have large leakage currents at frequencies below 5 kHz. The leakage current decreases significantly as the frequency approaches 10 kHz. The positive up negative down (PUND) measurement was used to obtain the remanent polarization of the films, and it was found that the remanent polarization values were not the same in the positive and negative directions, indicating that the electrode material has an effect on the ferroelectric properties. Full article

Dementia-associated compulsive singing (DACS) is a neurotransmettitorial-based behavioral disturbance, characterized by an unabating melodic expression, occurring in patients that suffer from evolved dementia. Previously described only as a “punding” aspect of the dopamine dysregulation syndrome (DDS) in the Parkinson’s disease (PD), compulsive singing has now been described, for the first time, in four non-PD patients effectively treated with Haloperidol or Quetiapine. Unlike the DDS-associated conditions, in our cases DACS is not pharmacologically induced, being that all patients were L-dopa-free. We detected a diffuse hyperintensity of the white matter and brain atrophy, with insular shrinkage as well as ventricular system and/or sub-arachnoid space enlargement in our DACS patients. Furthermore, similarly to the other behavioral symptoms of dementia, DACS also seems to be correlated to the degree of cognitive and functional impairment, rather than its subtype. In conclusion, DACS is a non-cognitive, unpublished clinical aspect of evolved dementia, which is interesting due to the involvement of the extra-nigral dopaminergic system, resulting in an unabating altered behavior, but also to the enrichment of our knowledge in the involutional diseases of the central nervous system and their physiopathological manifestations. Full article

Bi_1−xNd_xFe_0.99Mn_0.01O₃ (BNFMO, x = 0.00~0.20) films were epitaxially grown on Nb:SrTiO₃ (001) substrates using pulsed laser deposition. It was found that the Nd-doping concentration has a great impact on the surface morphology, crystal structure, and electrical properties. BNFMO thin film with low Nd-doping concentration (≤16%) crystallizes into a rhombohedral structure, while the high Nd-doping (>16%) will lead to the formation of an orthogonal structure. Furthermore, to eliminate the resistive switching (RS) effect, a positive-up–negative-down (PUND) measurement was applied on two devices in series. The remnant polarization experiences an increase with the Nd-doping concentration increasing to 16%, then drops down with the further increased concentration of Nd. Finally, the ferroelectric photovoltaic effect is also regulated by the ferroelectric polarization, and the maximum photocurrent of 1758 μA/cm² was obtained in Bi_0.84Nd_0.16Fe_0.99Mn_0.01O₃ thin film. BNFMO films show great potential for ferroelectric and photovoltaic applications. Full article

Parkinson’s Disease (PD) is a neurodegenerative disease in which non-motor symptoms may appear before motor phenomena, which include Impulse Control Disorders (ICDs). The objective of this study is to identify factors associated with the development of ICDs in PD. An analytical, cross-sectional study was conducted using clinical records from patients diagnosed with PD, both genders, from 40 to 80 years old. Clinical and demographic data were collected: 181 patients were recruited; 80 of them showed PD and ICDs, and they constituted the study group, whereas 101 patients with PD without ICDs constituted the control reference group. The duration of PD was longer in the group with ICDs (p < 0.008), and all patients showed at least one ICD: binge eating (61.29%), compulsive shopping (48.75%), hypersexuality (23.75%), gambling behavior (8.75%), and punding (3.75%). After logistic regression analysis, only the use of dopamine agonists remained associated with ICDs (p < 0.001), and the tremorgenic form was suggested to be a protective factor (p < 0.001). Positive associations were observed between the rigid-akinetic form and compulsive shopping (p < 0.007), between male and hypersexuality (p < 0.018), and between dopamine agonists and compulsive shopping (p < 0.004), and negative associations were observed between motor fluctuations and compulsive shopping (p < 0.031), between Deep Brain Stimulation and binge eating (p < 0.046), and between levodopa consumption and binge eating (p < 0.045). Binge eating, compulsive shopping, and hypersexuality were the most frequent ICDs. Complex forms and motor complications of PD were associated with the development of ICDs. Full article

Single crystalline magnetite Fe₃O₄ was investigated at low temperatures in the charge ordered state by electric measurements and time-resolved diffraction with voltage applied in-situ. Dielectric spectroscopy indicates relaxor ferroelectric characteristics, with polarization switching observably only at sufficiently low temperatures and in a suitably chosen time-window. PUND measurements with a ms time scale indicate a switchable polarization of about 0.6 µC/cm². Significant switching occurs only above a threshold field of about 3 kV/mm, and it occurs with a time delay of about 20 µs. The time-resolved diffraction experiment yields, for sufficiently high voltage pulses, a systematic variation by about 0.1% of the intensity of the ( $2,\overline{2},\overline{10}$ ) Bragg reflection, which is attributed to structural switching of domains of the non-centrosymmetric $Cc$ structure to its inversion twins, providing proof of intrinsic ferroelectricity in charge ordered magnetite. Full article