Nanotechnology最新文献

Over the past decade, graphene quantum dots have gained an inexhaustible deal of attention due to their unique zero-dimensional and quantum confinement properties, which boosted their wide research implication and reliable applications. As one of the promising zero-dimensional member and rising star of the carbon family, plant leaf-derived graphene quantum dots have attracted significant attention from scholars working in different research fields. Owing to its novel photophysical properties including high photo-stability, plant leaf-derived graphene quantum dots have been increasingly utilized in the fabrication of optoelectronic devices. Their superior biocompatibility finds their use in biotechnology applications, while their fascinating spin and magnetic properties have maximized their utilization in spin-manipulation devices. In order to promote the applications of plant leaf-derived graphene quantum dots in different fields, several studies over the past decade have successfully utilized plant leaf as sustainable precursor and synthesized graphene quantum dots with various sizes using different chemical and physical methods. In this review, we summarize the Neem and Fenugreek leaves based methods of synthesis of plant leaf-derived graphene quantum dots, discussing their surface characteristics and photophysical. We highlight the size and wavelength dependent photoluminescence properties of plant leaf-derived graphene quantum dots towards their applications in optoelectronic devices such as white light-emitting diodes and photodetectors, as well as biotechnology applications such as in vivo imaging of apoptotic cells and spin related devices as magnetic storage medium. Finally, we particularly discuss possible ways of fine tuning the spin properties of plant leaf-derived graphene quantum dot clusters by incorporation with superconducting quantum interference device, followed by utilization of atomic force microscopy and magnetic force microscopy measurements for the construction of future spin-based magnetic storage media and spin manipulation quantum devices so as to provide an outlook on the future spin applications of plant leaf-derived graphene quantum dots.

Environmental, safety, health, and sustainability (ESHS) have become an indispensable issue in the semiconductor industry. The 'Beyond CMOS' chapter of the International Roadmap for Devices and Systems roadmap introduces the concept of 'Green materials', emphasizing their importance for maintaining sustainability in semiconductor manufacturing. We discuss the current trends of emerging architectures and devices in the perspective of 'Green materials'. Additionally, we highlight the significance of benchmarking and standardization in advancing sustainable practices within the semiconductor industries.

Zinc phthalocyanine (ZnPc), a promising second-generation photosensitizer, suffers from decreased quantum yield of singlet oxygen due to poor water solubility and prone-to-aggregation nature in both physiological environment and solid matrix. To address this issue, in this work we reported a simple ligand-assisted reprecipitation method to prepare aggregation-free ZnPc-doped nanoparticles (NPs). Specifically, a short-chain ligand hexylamine was introduced to coordinate with ZnPc during reprecipitation, so that to alleviate ZnPc aggregation in the polymeric nanomatrix. As a consequence, the as-prepared ZnPc-loaded NPs with an optimal loading content of 4 wt.% acquired a high singlet oxygen quantum yield (Φ_Δ) of 0.5, which was comparable to that of ZnPc monomer (Φ_Δ= 0.55). Moreover, 10 wt.% ZnPc-loaded NPs could still retain a singlet oxygen quantum yield of 0.38. Taking advantage of the aggregation-free nano-photosensitizers (NPSs), efficient photodynamic therapy effect was achieved on HeLa cells upon 660 nm photo-irradiation with an ultra-low light dose (1.8 J cm^-2). This study not only presented a high efficient ZnPc-based NPS, but also proposed a new strategy to reduce the aggregation of metal complex in solid matrix through ligand coordination.

The excellent collection ability of the photo-generated holes from the poly-crystalline lead trihalide perovskite thin films to the poly[3-(4-carboxybutyl)thiophene-2,5,-diyl] (P3CT) or poly(3-hexylthiophene) (P3HT) polymer layer has been used to realize the highly efficient solar cells. The electronic and molecular structures of the p-type polymers play the decisive roles in the photovoltaic responses of the resultant perovskite solar cells. It is fundamental to understand the relation between the material properties and the photovoltaic performance in order to achieve the highest power conversion efficiency. We review the molecular packing, morphological, optical, excitonic, and surface properties of the P3CT and P3HT polymer layers in order to correctly understand the working mechanisms of the resultant solar cells, thereby predicting the required material properties of the used p-type polymers as the efficient hole transport layer.

Localized surface plasmon resonance (LSPR) is an optical phenomenon associated with noble metal nanostructures. The resonances result in sharp spectral absorption peaks as well as enhanced local electromagnetic fields, which have been widely used in chemical and biological sensing. Over the past decade, as label-free analytical method, LSPR sensors have gained considerable interest and undergone rapid development. In addition to conventional refractive-index sensing through resonant wavelength shift, molecular sensing by colorimetry and imaging techniques have also been developed. Moreover, the LSPR sensors have been integrated with other techniques such as micro/nano fluidics and artificial intelligence to enhance their functionality and performances. In this work, we provide an overview of the recent advancement in LSPR sensors technology, including refractive-index, colorimetric, and imaging-based sensors., as well as the incorporation of new technologies like artificial intelligence. .

Bare silicon dimers on hydrogen-terminated Si(100) have two dangling bonds. These are atomically localized regions of high state density near to and within the bulk silicon band gap. We studied bare silicon dimers as monomeric units. Silicon dimer wires are much more stable than wires composed of individual dangling bonds. Dimer wires composed of 1-5 dimers were intentionally fabricated and characterized by STM techniques combined with density functional theory to provide detailed insights into geometric and electronic structure. Structural and dynamic qualities displayed by short wires were shown to be similar to the characteristics of a relatively long 37 dimer wire. Rather than adding two states into the band gap, experiment and theory reveal that each dimer adds one empty state into the gap and one filled state into the valence bands. Coupling among these states provides a conduction pathway with small bulk coupling.

Solid-state nanopores exhibit adjustable pore size, robust chemical and thermal stability, and compatibility with semiconductor fabrication, positioning them as versatile platforms for nanofluidic applications and single-molecule detection. However, their higher noise levels compared to biological nanopores hinder their sensitivity in detecting biomolecules such as DNA and proteins. Enhancing detection sensitivity requires an in-depth understanding of noise sources and strategies for noise reduction. Here, we construct an equivalent circuit model of solid-state nanopores and conduct corresponding experiments to evaluate how chip capacitance, salt concentration, applied voltage, and pore size influence ionic current noise. We find that chip capacitance is the dominant factor affecting ionic current noise, with minimal noise sensitivity to salt concentration below 0.1 M but pronounced increases above this threshold. The pH has little impact on noise, whereas higher applied voltages elevate noise at high salt concentrations. Introducing a SiO₂layer between SiN_xand Si significantly reduces chip capacitance; a 1000 nm SiO₂layer reduces capacitance to 7.9 pF, decreasing ionic current noise to 18.7 pA for a 2.2 nm nanopore in 1 M KCl at 40 μm membrane side length and 100 mV and 10 kHz sampling. This reduction in capacitance improves response time and measurement accuracy, marking a critical advancement for high-sensitivity applications of solid-state nanopores.

Growth of GaN nanowires (NWs) on graphene substrates is carried out by plasma-assisted molecular beam epitaxy. We test a two-step growth procedure consisting of a first stage at relatively low temperature followed by a second stage at higher temperature. We investigate the impact of this process on the usually long incubation time which precedes the first GaN nucleation events on graphene. We also examine how the selectivity of growth between graphene and the surrounding SiO₂surface is affected. After optimization of this procedure, it is applied to the growth of GaN NWs on a graphene layer patterned by electron beam lithography. A clear advantage of the two-step growth is observed in terms of reduction of the incubation time and improvement of height uniformity.

The exceptional properties of boron nitride nanosheets (BNNSs) render them promising for diverse applications. Nevertheless, the obstacles of effectively readying them and their restricted ability to disperse in liquids are current constraints. In this study, a simple and efficient glucose-assisted mechanochemical exfoliation method was developed to achieve simultaneous exfoliation and functionalization of BNNSs. The BNNSs yield reached 87.5%, featuring grafted hydroxyl groups at the edges and well dispersed in water. Furthermore, the prepared BNNSs were dispersed into water and subsequently incorporated into a nanofiltration membrane using vacuum filtration. The vacuum filtration produced the BNNSs nanofiltration membrane with high water flux and flexibility interception rate due to its excellent dispersibility. The optimal interception rate of the BNNSs filter membrane for a 2 mg•ml-1 Congo red (CR) solution was 96.12%, and the optimal flux of the BNNSs filter membrane for pure water was 1312 L•m-2•h-1•bar-1 according to the experiments. Additionally, the adsorption performance of BNNSs with different functionalized groups (e.g., hydroxyl and amino) for CR and heavy metal ions (copper ions) was studied through density functional theory (DFT) theoretical calculations. This study not only present a highly efficient, environmentally friendly, and cost-effective method for preparing hydrophilic BNNSs to enhance their yield, but also investigated and predicted the interception rate and flux of BNNSs nanofiltration membranes functionalized with different functional groups for water contaminated with metal ions and dyes.

Amorphous boron nitride (aBN) films, with extremely low relative dielectric constant (κ) and chemical inertness, are excellent insulation and packaging materials for electronic device interconnection. It is of great significance to prepare the low-κaBN films with controllable thickness, but there are still some limitations to achieve the goal. In this study, we succeed in growing wafer-scale aBN films with specific thicknesses from 1.2 to 4.0 nm by varying the growth time and temperature. The thickness of the films increases linearly with growth time and the crystallinity of BN films is precisely controlled by the growth temperature. The preferred temperature for aBN films ranges from 200°C to 400°C. Raman spectroscopy, x-ray photoelectron spectroscopy and transmission electron microscope all confirm the amorphous feature. These films are wafer-scale uniformity and have an ultra-flat surface, with excellent thermal stability and corrosion resistance. Particularly, the growth temperature affects theκvalue and breakdown voltage of aBN films. The aBN films grown at 200°C have the lowestκvalue of 1.66 at 100 kHz, along with the breakdown field strength of 5.5 MV cm^-1. We believe that wafer-level aBN films with various thicknesses can bring new opportunities for the development and application of nanoscale electrical devices.