Nanotechnology最新文献

We report the first perovskite solar cell incorporating soybean lecithin, a biological plant-based food additive. When added in small concentration to perovskite precursor inks, it helps to obtain compact and uniform CsPbBr₃thin films. Our devices exhibit very high average visible transmittances (AVTs) (>70%), color rendering index (CRI) up to 84% and neutrality (CIE coordinates of 0.38, 0.39). The addition of lecithin almost doubled power conversion efficiency from 0.84% to 1.52%. Such high transparency, although limiting their overall efficiency, can be used in environments where transparency and color neutrality are important features, such as windows, facades, lens in smart glasses, and greenhouses. The transparency-efficiency profile fits the trend in performance of emerging photovoltaic devices, with amongst the highest voltages reported at these transmittances. Furthermore, the stability in ambient air also improved with addition of lecithin, losing only 25% of efficiency after 1 year versus 50% for devices with no lecithin.

Ferroelectric field-effect transistors (FeFETs), a type of ferroelectric memory with a transistor-based structure, have attracted significant attention from integrated circuit researchers due to their compact device architecture, non-destructive readout capability, and elimination of additional selector devices. These advantages make FeFETs highly promising for achieving higher storage density and enabling computing-in-memory applications. For their practical industrial deployment, extensive studies have been conducted on device fabrication, circuit design, and reliability. Among the key challenges, enlarging the memory window (MW) while maintaining stability is critical, as it directly affects data accuracy and retention. In this work, we experimentally investigate the modulation of the MW and interface defect density (ΔN_it) in Zr-doped HfO₂(HfZrO_x)-based FeFETs under different polarization states of the ferroelectric gate dielectric. The results demonstrate that with progressively enhanced ferroelectric polarization, the MW expands, while the interface trap density is simultaneously suppressed, suggesting that robust polarization effectively inhibits the formation of interface defects and improves subthreshold swing characteristics of the device. Furthermore, TCAD simulations were conducted to systematically investigate the impact of various ferroelectric properties, including remanent polarization (P_r), saturation polarization (P_s) and variations in coercive field (E_c), on the memory characteristics of HfZrO_xFeFETs. It was confirmed that higher polarization can alleviate the degradation caused by defects. In addition, an increase inP_randP_s, together with a lowerE_c, enhances the surface potential difference, charge separation, and switching efficiency, thereby improving both the MW and the stability of the device. This study provides valuable insights for the development of reliable FeFET-based memory technologies.

Two-dimensional (2D) materials offer an exceptional platform for exploring quantum phenomena, as their reduced dimensionality significantly enhances tunability via external parameters. Among these, superconductivity in 2D systems is of particular interest due to its fundamental significance and potential applications in quantum technologies. Despite ongoing experimental challenges in realizing novel 2D superconductors, first-principles calculations have emerged as powerful tools for guiding their prediction and design. While many prior reviews focus broadly on low-dimensional superconductivity, this article specifically surveys computationally predicted 2D superconductors, with an emphasis on the underlying theoretical frameworks and their limitations. We highlight how external perturbations such as strain, doping, chemical functionalization, and intercalation, modify electron-phonon coupling and superconducting critical temperatures, and we examine cases where superconductivity competes or coexists with other quantum orders, including charge density waves and nontrivial band topology. We further discuss the growing role of machine-learning and high-throughput approaches in accelerating materials discovery, along with the challenges associated with data quality and model reliability. Overall, this review underscores the potential and current limitations of first-principles and data-driven approaches in advancing the understanding and discovery of 2D superconductors.

Graphyne (GY) nanomaterials, with their highly tunable properties, show great potential as building blocks for composite nanodevices. Using molecular dynamics simulations, this study investigates the bi-directional folding and unfolding evolution of homogeneous and heterogeneous GY nanoribbons (GYNRs) around a rotating carbon nanotube (CNT). The results reveal distinct configuration rules: homogeneous GYNRs consistently undergo synchronous folding to form interlaced GY nanoscrolls (GYNSs), whereas heterogeneous GYNRs may fold synchronously or in a layered manner, producing either interlaced or covered GYNSs depending on atomic density differences (ADDs) and temperature. Moreover, GYNSs can be reversibly unfolded into GYNRs under CNT rotation. Unified unfolding, initiated from the innermost layer, typically occurs in interlaced GYNSs, while segmented unfolding-unique to covered GYNSs with large ADDs-proceeds sequentially from the outermost edge of the outer GYNS to the innermost layer of the inner GYNS. These findings establish key principles for the flexible design and engineering of novel homo- and heterogeneous GY-based nanostructures.

Large area, vertically aligned one-dimensional, hexagonally patterned materials have been found to be efficient substrates for surface enhanced Raman spectroscopy (SERS). Here in this work, we have developed a facile substrate for SERS performance as vertically grown carbon nanopillars (CNPs) inside the porous hexagonally patterned anodic aluminum oxide (AAO). Nanoporous AAO was grown for the best pore ordering for optimum parameters. CNPs were synthesized in the AAO template inside a thermal chemical vapor deposition reactor. CNPs were exposed to mechanical polishing to remove excess overgrown amorphous carbon, followed by chemical etching. This facile SERS substrate was prepared by depositing Au to form SERS-active hot spots. This CNP-Au hybrid substrate for 30 nm Au deposition shows the uniform sub-10 nm gap between subsequent nanopillars. Based on UV-Vis spectroscopy, the plasmonic resonance of the CNP-Au substrate was observed at a wavelength of approximately 540 nm. Rhodamine (R6G) dye was investigated for its very low concentration up to 10^-9M due to its genotoxic and carcinogenic effects on human life. Thus, a low concentration of R6G analyte is strongly desired for sensitive detection. The electric field enhancement was validated with a 3D FDTD Lumerical simulation for CNP@Au-30 nm substrate for a 10 nm gap. This CNP@Au facile SERS substrate shows potential use for novel large-area electrode systems in next-generation optoelectronics, including photovoltaics, light-emitting diodes, ultralow molecule detection, and solar water splitting.

As CMOS technology scales into the nanoscale regime, ensuring the reliability of digital circuits in radiation-rich environments has become a critical challenge. Standard cell libraries, which are foundational to digital design, are typically characterized using extensive SPICE simulations to capture gate delays as functions of input transition time and load capacitance. However, these libraries do not account for total ionizing dose (TID) effects, which are caused by prolonged exposure to ionizing radiation and introduce oxide-trapped charges and interface states that degrade key transistor parameters, such as threshold voltage and leakage current. This results in significant timing inaccuracies, compromising digital timing closure in mission-critical applications such as aerospace and nuclear electronics. In this work, we propose an efficient, TID-aware standard cell characterization methodology for nanoscale CMOS technologies that generates cell characterization data in standard Liberty format, enabling accurate prediction of timing closure under TID influence without incurring any SPICE simulation overhead. Our approach leverages well-calibrated 32 nm Synopsys^©Sentaurus TCAD simulations and variation-aware analytical timing models to capture TID-induced degradation. These effects are incorporated into cell netlists through adjustments to the BSIM parameters to generate both pre- and post-radiation standard cell libraries. Validated using a set of reference designs, including ISCAS benchmark circuits, the proposed methodology achieves accurate path-level timing predictions under radiation while reducing SPICE simulation effort by approximately 81.25%. By bridging device-level radiation effects with cell-level timing abstraction, this scalable framework offers a practical solution for robust and radiation-resilient digital integrated circuit design in harsh environments.

Semiconductor nanowires have continued to be an important material format for both fundamental science and device research. Recent years have witnessed a fantastic progress on semiconductor nanowires across different material systems, such as II-VI, III-V, III-nitrides, and so on. In this review paper, I would like to focus on some of the recent developments in III-nitride nanowires and their device applications. A specific III-nitride nanowire synthesis technique, molecular beam epitaxy (MBE), which is a highly controllable, scalable, and industrial production compatible material synthesis technique, is focused. Recent understanding about the MBE growth of III-nitride nanowires, including low temperature selective area epitaxy and chamber configuration dependent properties, is discussed. Moreover, recent advances on III-nitride nanowire light-emitting and photodetection devices are discussed. In addition, emerging studies on scandium (Sc) incorporated III-nitride nanowires and devices are discussed. The intention of this review paper is to complement recent reviews in the field of III-nitride nanowire research and provide readers some future perspectives on this intriguing semiconductor material system.

Using the mean-field approximation, a formula for the effective electrical conductivity of a two-dimensional system of randomly arranged conducting sticks with a given orientation distribution was obtained. Both the resistance of the sticks themselves and the resistance of the contacts between them were taken into account. The accuracy in the resulting formula was analyzed. A comparison of the theoretical predictions of mean-field approach with the results of direct electrical conductivity calculations for several model orientation distributions describing systems with crossed sticks demonstrated good agreement. Our study showed that cross-alignment of nanowires should lead to a decrease in the electrical conductivity compared to electrodes with isotropically arranged nanowires. We suppose that the widely used model with zero-width sticks is quite acceptable for systems of cross-aligned nanowires, but overestimates their connectivity in isotropic systems. Thus, the enhancement of the electrical conductivity of conducting films with cross-aligned nanowires may be due to a significant difference in the network topology.

We have conducted a detailed investigation of helium ion beam lithography (HIBL) at its resolution limits by calculating three-dimensional energy deposition within a resist. The resist activation energy, a critical physical parameter, was estimated and used as a substitute for the traditionalz-factor, allowing for a systematic evaluation of interdependent lithography performances. Our calculations demonstrate HIBL's exceptional capabilities, including 2.5 nm resolution (30 kV, PMMA, line-scan), large aspect ratios exceeding 9, a proximity effect range of approximately 10 nm at 100 nm depth, and edge roughness below 1 nm. These findings highlight HIBL's potential for advanced nanofabrication applications. Furthermore, our calculation led to a reliable model for accurate pattern prediction and proximity effect corrections, which was verified by experiment.

Increased emissions of volatile organic compounds (VOCs) are prone to cause health issues like cancer and central nervous system disorders, making the development of efficient VOCs-sensing materials crucial. Monolayerα-AsN, a two-dimensional (2D) V-V binary material with a wrinkled honeycomb structure, features better environmental stability (higher cohesive energy than black phosphorus, BP) and tunable electrical properties (unlike single-target VOC-sensing TMDs). It overcomes flaws of existing 2D sensors (BP's poor stability, TMDs' narrow selectivity) while retaining high surface-to-volume ratio, and shows superior adsorption efficiency and selectivity for alcohol VOCs versus BP and acetone-specialized Janus TMDs. However, its VOCs-sensing performance remains uninvestigated. This study employed density functional theory and nonequilibrium Green's function to systematically investigate the adsorption and sensing behaviors of monolayerα-AsN toward the five VOCs. Electronic localization function analysis confirmed physical adsorption (no chemical bonding) betweenα-AsN and all VOCs. Among the tested VOCs, methanol and ethanol exhibited the highest adsorption energy and density (ethanol slightly higher), with ultra-low detection limits (7.69 × 10^-⁴ p.p.b. for methanol and 4.88 × 10^-⁵ p.p.b. for ethanol). Critically, methanol adsorption reducedα-AsN's current by 30%, while ethanol increased it by 100%. These findings demonstrate that monolayerα-AsN holds great application potential for the selective detection of methanol and ethanol.