Nano Convergence最新文献

This study investigates the impact of dopants on Hf_1–xZr_xO₂-based capacitors for high-performance, hysteresis-free dielectric applications. Control of the crystalline structure of Hf_1–xZr_xO₂ films is crucial for achieving superior dielectric properties. The tetragonal (t) phase of Hf_1–xZr_xO₂ exhibits anti-ferroelectric (AFE) characteristics and shows promise due to its high dielectric constant (κ). However, hysteresis behavior in polarization–voltage sweeps due to AFE behavior presents a significant challenge, primarily due to the high energy loss when implemented in dynamic random-access-memory (DRAM) applications. To achieve hysteresis-free operation, this study focuses on suppressing AFE switching within the DRAM voltage range through Si or La doping in Hf_1–xZr_xO₂ films. Introducing small amounts of Si or La (< 1%) into Hf_1–xZr_xO₂ capacitors effectively diminishes AFE switching by influencing which structural phases are favored: Si doping tends to favor the amorphous phase, while La doping promotes the formation of the t-phase. La doping shows particular promise in enhancing pseudo-linear dielectric performance. ~ 0.9% La-doped Hf_0.25Zr_0.75O₂ capacitors exhibit a markedly improved equivalent oxide thickness (EOT) of ~ 4.8 Å and a reduced leakage current density (J_leak) of ~ 10^–7 A/cm² at 1 V, achieved at back-end-of-line (BEOL) compatible temperatures (< 400 °C). These results demonstrate a promising strategy for advancing energy-efficient high-κ dielectric materials in next-generation memory devices, offering a balanced combination of high capacitance, low leakage current, and BEOL compatibility.

Graphical Abstract

Sneak current issues in crossbar arrays of non-volatile memories can be effectively alleviated using threshold switching (TS)-based selectors. However, 1-selector–1-resistor integration requires coherence between the constituent materials and operational parameters of the two components. Here, we propose a highly coherent selector via in-depth investigation of the operation process of a fab-friendly As-SiO₂ selector unit. The structural and electrical characteristics of an As-embedded SiO₂ selector are analyzed, and the TS-on and -off operational mechanism is presented. Further, the critical control elements governing the selector operation are identified, including the electron charging into the oxygen vacancies in the SiO₂ matrix and energy band alignment between the As cluster and charged oxygen vacancies in SiO₂. Consequently, practical control strategies for the TS behavior are proposed with a pulse scheme applicable to actual device operation. The proposed TS operational mechanism and analytical methodology can contribute to interpreting and integrating various memory/selector components, thereby advancing their operational and integrative research.

Graphical abstract

Recent development of controlling quantum systems has enabled us to utilize the systems for quantum computing, communication, and sensing. In particular, quantum sensing has attracted attention to a broad community of science and technology, as it could surpass classical limitations in measuring physical quantities such as electric and magnetic field with unprecedented precision. Among various physical platforms for quantum sensing, trapped-ion based system possesses several advantages—atomic size, outstanding quantum coherence, and quantum properties. In this review, we introduce previous research efforts to utilize the trapped-ion system for reaching ultimate sensitivity and discuss future perspective and research directions in this emerging field.

Graphical Abstract

The upcoming generation of functional electronics in the era of artificial intelligence, and IoT requires extensive data storage and processing, necessitating further device miniaturization. Conventional Si CMOS technology is struggling to enhance integration density beyond a certain limit to uphold Moore’s law, primarily due to performance degradation at smaller dimensions caused by various physical effects, including surface scattering, quantum tunneling, and other short-channel effects. The two-dimensional materials have emerged as highly promising alternatives, which exhibit excellent electrical and mechanical properties at atomically thin thicknesses and show exceptional potential for future CMOS technology. This review article presents the chronological progress made in the development of two-dimensional materials-based CMOS devices with comprehensively discussing the advancements made in material production, device development, associated challenges, and the strategies to address these issues. The future prospects for the use of two-dimensional materials in functional CMOS circuitry are outlooked, highlighting key opportunities and challenges toward industrial adaptation.

Graphical Abstract

The interest in highly sensitive sensors is rapidly increasing for detecting very tiny signals for Internet of Things devices. Here, we achieve ultra-sensitive correlated breathable sensors based on freestanding VO₂ membranes. We fabricate the membranes by growing VO₂ films onto sacrificial Sr₃Al₂O₆ layer grown on SrTiO₃, selectively dissolving the Sr₃Al₂O₆ in water, and then rendering freestanding VO₂ membrane on nanomesh. The nanomeshes are extremely flexible, sweat permeable, and readily skin-adhesive. The resistance of the VO₂ membranes is reversibly tuned by human’s tiny mechanical stimuli and breath stimuli. The stimuli modulate the Peierls dimerization of one-dimensional V−V chains in the VO₂ lattice which concomitantly controls the electron correlation and hence resistivity. Since our breathable sensors operate based on quantum-mechanical correlation effects, their sensitivity is 1−2 orders of magnitude higher than conventional tactile and respiratory sensors based on other materials. Thus, the freestanding membranes of correlated oxides on epidermal nanomeshes are multifunctional platforms for developing ultra-sensitive correlated breathable sensors.

Graphical Abstract

Acute lung injury (ALI) is characterized by severe inflammation in lung tissue, excessive immune response and impaired lung function. In hospitalized high-risk patients and cases of secondary infection due to surgical contamination, it can lead to higher mortality rates and require immediate intervention. Currently, clinical treatments are limited in symptomatic therapy as mechanical ventilation and corticosteroids, having insufficient efficacy in mitigating the cause of progression to severe illness. Here we report a pulmonary targeting lung-homing nanoliposome (LHN) designed to attenuate excessive Neutrophil Extracellular Trap formation (NETosis) through sivelestat and DNase-1, coupled with an anti-inflammatory effect mediated by 25-hydroxycholesterol (25-HC), offering a promising intervention for the acute phase of ALI. Through intratracheal delivery, we intend prompt and constant action within the lungs to effectively prevent excessive NETosis. Isolated neutrophils from blood samples of severe ARDS patients demonstrated significant anti-NETosis effects, as well as reduced proinflammatory cytokine secretion. Furthermore, in a murine model of LPS-induced ALI, we confirmed improvements in lung histopathology, and early respiratory function. Also, attenuation of systemic inflammatory response syndrome (SIRS), with notable reductions in NETosis and neutrophil trafficking was investigated. This presents a targeted therapeutic approach that can be applied in early stages of high-risk patients to prevent severe pulmonary disease progression.

Metal-oxide thin-film semiconductors have been highlighted as next-generation space semiconductors owing to their excellent radiation hardness based on their dimensional advantages of very low thickness and insensitivity to crystal structure. However, thin-film transistors (TFTs) do not exhibit intrinsic radiation hardness owing to the chemical reactions at the interface exposed to ambient air. In this study, significantly enhanced radiation hardness of Al₂O₃-passivated ZnO TFTs against high-energy protons with energies of up to 100 MeV is obtained owing to the passivation layer blocking interactions with external reactants, thereby maintaining the chemical stability of the thin-film semiconductor. These results highlight the potential of passivated metal-oxide thin films for developing reliable radiation-hardened semiconductor devices that can be used in harsh space environments. In addition, the relationship between low-frequency noise and defects due to oxygen vacancies was revealed, which can be utilized to improve device reliability.