Schottky nanocontacts on ZnO nanorod arrays

We report on fabrication and electrical characteristics of ZnO nanorod Schottky diode arrays. High quality ZnO nanorods were grown for the fabrication of the Schottky diodes using noncatalytic metalorganic vapor phase epitaxy and Au was evaporated on the tips of the vertically well-aligned ZnO nanorods. I-V characteristics of both bare ZnO and Au/ZnO heterostructure nanorod arrays were measured using current-sensing atomic force microscopy. Although both nanorods exhibited nonlinear and asymmetric I-V characteristic curves, Au/ZnO heterostructure nanorods demonstrated much improved electrical characteristics: the reverse-bias breakdown voltage was improved from -3 to -8 V by capping a Au layer on the nanorod tips. The origin of the enhanced electrical characteristics for the heterostructure nanorods is suggested. (C) 2003 American Institute of Physics.X11326sciescopu

Time-resolved photoluminescence of the size-controlled ZnO nanorods

Size dependence of the time-resolved photoluminescence (TRPL) has been investigated for the ZnO nanorods fabricated by catalyst-free metalorganic chemical vapor deposition. The nanorods have a diameter of 35 nm and lengths in the range of 150 nm to 1.1 mum. The TRPL decay rate decreases monotonically as the length of the nanorods increases in the range of 150 to 600 nm. Decrease of the radiative decay rate of the exciton-polariton has been invoked to account for the results. (C) 2003 American Institute of Physics.X11100sciescopu

Fabrication and electrical characteristics of high-performance ZnO nanorod field-effect transistors

We report on fabrication and electrical characteristics of high-mobility field-effect transistors (FETs) using ZnO nanorods. For FET fabrications, single-crystal ZnO nanorods were prepared using catalyst-free metalorganic vapor phase epitaxy. Although typical ZnO nanorod FETs exhibited good electrical characteristics, with a transconductance of similar to140 nS and a mobility of 75 cm(2)/V s, the device characteristics were significantly improved by coating a polyimide thin layer on the nanorod surface, exhibiting a large turn-ON/OFF ratio of 10(4)-10(5), a high transconductance of 1.9 muS, and high electron mobility above 1000 cm(2)/V s. The role of the polymer coating in the enhancement of the devices is also discussed. (C) 2004 American Institute of Physics.X11333sciescopu

Electrical and optical characteristics of hydrogen-plasma treated ZnO nanoneedles

We report on optical characteristics as well as electron emission of hydrogen-plasma treated ZnO nanoneedle arrays. The nanoneedle arrays were vertically grown on Si substrates using catalyst-free metalorganic chemical vapor deposition and subsequently treated by hydrogen plasma at room temperature. After hydrogen plasma treatment, the field emission characteristic curves of nanoneedle arrays exhibited significantly reduced turn-on field and increased emission current density, and the electrical conductivity was increased. In addition, low temperature photoluminesence (PL) measurements indicate that a neutral-donor bound exciton PL peak intensity was increased by the hydrogen- plasma treatment. These effects of the plasma treatment on the physical properties may be explained in terms of hydrogen doping effect. (c) 2005 American Vacuum Society.open112224sciescopu

Evidence of pores and thinned lipid bilayers induced in oriented lipid membranes interacting with the antimicrobial peptides, magainin-2 and aurein-3.3

AbstractDynamic structures of supramolecular lipid assemblies, such as toroidal pores and thinned bilayers induced in oriented lipid membranes, which are interacting with membrane-acting antimicrobial peptides (AMPs), magainin-2 and aurein-3.3, were explored by 31P and 2H solid-state NMR (ssNMR) spectroscopy. Various types of phospholipid systems, such as POPC-d31, POPC-d31/POPG, and POPC-d31/cholesterol, were investigated to understand the membrane disruption mechanisms of magainin-2 and aurein-3.3 peptides at various peptide-to-lipid (P:L) ratios. The experimental lineshapes of anisotropic 31P and 2H ssNMR spectra measured on these peptide–lipid systems were simulated reasonably well by assuming the presence of supramolecular lipid assemblies, such as toroidal pores and thinned bilayers, in membranes. Furthermore, the observed decrease in the anisotropic frequency span of either 31P or 2H ssNMR spectra of oriented lipid bilayers, particularly when anionic POPG lipids are interacting with AMPs at high P:L ratios, can directly be explained by a thinned membrane surface model with fast lateral diffusive motions of lipids. The spectral analysis protocol we developed enables extraction of the lateral diffusion coefficients of lipids distributed on the curved surfaces of pores and thinned bilayers on a few nanometers scale

Excitonic emissions observed in ZnO single crystal nanorods

We report on the photoluminescent characteristics of ZnO single crystal nanorods grown by catalyst-free metalorganic vapor phase epitaxy. From photoluminescence (PL) spectra of the nanorods at 10 K, several PL peaks were observed at 3.376, 3.364, 3.360, and 3.359 eV. The PL peak at 3.376 eV is attributed to a free exciton peak while the other peaks are ascribed to neutral donor bound exciton peaks. The observation of the free exciton peak at 10 K indicates that ZnO nanorods prepared by the catalyst-free method are of high optical quality. (C) 2003 American Institute of Physics.open11374393sciescopu

Metalorganic vapor-phase epitaxial growth of vertically well-aligned ZnO nanorods

We report metalorganic vapor-phase epitaxial growth and structural and photoluminescent characteristics of ZnO nanorods. The nanorods were grown on Al2O3(00.1) substrates at 400 degreesC without employing any metal catalysts usually needed in other methods. Electron microscopy revealed that nanorods with uniform distributions in their diameters, lengths, and densities were grown vertically from the substrates. The mean diameter of the nanorods is as narrow as 25 nm. In addition, x-ray diffraction measurements clearly show that ZnO nanorods were grown epitaxially with homogeneous in-plane alignment as well as a c-axis orientation. More importantly, from photoluminescence spectra of the nanorods strong and narrow excitonic emission and extremely weak deep level emission were observed, indicating that the nanorods are of high optical quality. (C) 2002 American Institute of Physics.open1110681105sciescopu

Formation and photoluminescent properties of embedded ZnO quantum dots in ZnO/ZnMgO multiple-quantum-well-structured nanorods

ZnO/Zn0.8Mg0.2O multiple-quantum-well (MQW) nanorods with a different number of periods and well widths were grown by catalyst-free metal-organic vapor phase epitaxy. Their optical and structural characteristics were investigated using photoluminescence, transmission electron microscopy, and field emission scanning electron microscopy. Unlike ZnO/ZnMgO MQW thin films, it was observed that embedded quantum dots played a more important role in the optical characteristics of ZnO/ZnMgO MQW nanorods than quantum confined Stark effect due to polarization field. (c) 2006 American Institute of Physics.open112324sciescopu

Improving 3D Imaging with Pre-Trained Perpendicular 2D Diffusion Models

Diffusion models have become a popular approach for image generation and reconstruction due to their numerous advantages. However, most diffusion-based inverse problem-solving methods only deal with 2D images, and even recently published 3D methods do not fully exploit the 3D distribution prior. To address this, we propose a novel approach using two perpendicular pre-trained 2D diffusion models to solve the 3D inverse problem. By modeling the 3D data distribution as a product of 2D distributions sliced in different directions, our method effectively addresses the curse of dimensionality. Our experimental results demonstrate that our method is highly effective for 3D medical image reconstruction tasks, including MRI Z-axis super-resolution, compressed sensing MRI, and sparse-view CT. Our method can generate high-quality voxel volumes suitable for medical applications.Comment: ICCV23 poster. 15 pages, 9 figure

Long-term Time Series Forecasting based on Decomposition and Neural Ordinary Differential Equations

Long-term time series forecasting (LTSF) is a challenging task that has been investigated in various domains such as finance investment, health care, traffic, and weather forecasting. In recent years, Linear-based LTSF models showed better performance, pointing out the problem of Transformer-based approaches causing temporal information loss. However, Linear-based approach has also limitations that the model is too simple to comprehensively exploit the characteristics of the dataset. To solve these limitations, we propose LTSF-DNODE, which applies a model based on linear ordinary differential equations (ODEs) and a time series decomposition method according to data statistical characteristics. We show that LTSF-DNODE outperforms the baselines on various real-world datasets. In addition, for each dataset, we explore the impacts of regularization in the neural ordinary differential equation (NODE) framework.Comment: Accepted at IEEE BigData 202