Spectroscopic Ellipsometry and Correlated Studies of AlGaN-GaN HEMTs Prepared by MOCVD.

A series of AlGaN/GaN high-electron-mobility transistor (HEMT) structures, with an AlN thin buffer, GaN thick layer and AlGaN layer (13-104 nm thick), is prepared by metal-organic chemical vapor deposition and investigated via multiple techniques. Spectroscopic ellipsometry (SE) and temperature-dependent measurements and penetrative analyses have achieved significant understanding of these HEMT structures. Bandgaps of AlGaN and GaN are acquired via SE-deduced relationships of refraction index n and extinguish coefficient k vs.

Effects of Substrate Temperature on Optical, Structural, and Surface Properties of Metal-Organic Vapor Phase Epitaxy-Grown MgZnO Films.

MgZnO possesses a tunable bandgap and can be prepared at relatively low temperatures, making it suitable for developing optoelectronic devices. MgZnO (~0.1) films were grown on sapphire by metal-organic vapor phase epitaxy under different substrate-growth temperatures of 350-650 °C and studied by multiple characterization technologies like X-ray diffraction (XRD), spectroscopic ellipsometry (SE), Raman scattering, extended X-ray absorption fine structure (EXAFS), and first-principle calculations.

Nickel-Catalyzed Three-Component 1,1-Difunctionalization of Unactivated Alkenes with Quinoxaline/Naphthoquinone and Arylboronic Acids via Organometallic-Radical Relay.

A nickel-catalyzed intermolecular three-component 1,1-difunctionalization of unactivated alkenes with quinoxaline/naphthoquinone and arylboronic acids via organometallic-radical relay is developed. This efficient protocol provides a new method to access a variety of arylalkanes in moderate to good yields with a broad substrate scope and excellent functional group tolerance. The mechanistic studies provide insights into the mechanism and origin of chemo- and regioselectivity as well as confirm the generation of functionalized benzylic radicals.

Durable Multilayered Sleeve-Structured Hybrid Nanogenerator for Efficient Water Wave Energy Harvesting.

The state-of-the-art triboelectric nanogenerator (TENG) technology has numerous advantages and creates new prospects for the rapid development of the Internet of Things (IoT) in marine environments. Here, to accelerate the application process of TENG, an elaborately designed multilayered sleeve-structured hybrid nanogenerator (M-HNG) is developed to efficiently and persistently harvest marine energy. The M-HNG integrates an electromagnetic nanogenerator (EMG) with four coils and a multilayered sleeve-structured TENG (MS-TENG) with three freestanding layer units to increase spatial utilization efficiency.

Structural Quality Factor of Flo-TENG under Stochastic Wave Excitation.

Triboelectric nanogenerators (TENGs) have recently emerged as a promising technology for efficient water wave energy harvesting. However, there is a paucity of clear guidance regarding the optimal designs of TENGs and their shells to achieve efficient absorption and conversion of water wave energy in real random waves. Herein, from the perspective of wave-body interaction and energy transfer, this paper proposes a structural quality factor (Q) for the quantitative evaluation of both the motion of floating triboelectric nanogenerator (Flo-TENG) shells and their capability to absorb and convert water wave energy efficiently.

Optical, Structural, and Synchrotron X-ray Absorption Studies for GaN Thin Films Grown on Si by Molecular Beam Epitaxy.

GaN on Si plays an important role in the integration and promotion of GaN-based wide-gap materials with Si-based integrated circuits (IC) technology. A series of GaN film materials were grown on Si (111) substrate using a unique plasma assistant molecular beam epitaxy (PA-MBE) technology and investigated using multiple characterization techniques of Nomarski microscopy (NM), high-resolution X-ray diffraction (HR-XRD), variable angular spectroscopic ellipsometry (VASE), Raman scattering, photoluminescence (PL), and synchrotron radiation (SR) near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. NM confirmed crack-free wurtzite (w-) GaN thin films in a large range of 180-1500 nm.

Dual-coupling effect enables a high-performance self-powered UV photodetector.

Self-powered ultraviolet photodetectors generally operate by utilizing the built-in electric field within heterojunctions or Schottky junctions. However, the effectiveness of self-powered detection is severely limited by the weak built-in electric field. Hence, advances in modulating the built-in electric field within heterojunctions are crucial for performance breakthroughs.

High-Performance Piezoelectric Nanogenerator of BTO-PVDF Nanofibers for Wearable Sensing.

Piezoelectric nanogenerator (PENG) produces stable electrical signals in response to external mechanical stimuli and holds promise in the fields of flexible sensors and smart wearable devices. In practice, a high-performance PENG with a straightforward structure and exceptional reliability is deeply desired. This study optimally synthesizes piezoelectric composites comprising polyvinylidene fluoride (PVDF) incorporated with barium titanate (BTO) nanoparticles (NPs) and fabricated a PENG with heightened sensitivity by using the electrospinning technique.

Optical and Structural Properties of Aluminum Nitride Epi-Films at Room and High Temperature.

The high-quality aluminum nitride (AlN) epilayer is the key factor that directly affects the performance of semiconductor deep-ultraviolet (DUV) photoelectronic devices. In this work, to investigate the influence of thickness on the quality of the AlN epilayer, two AlN-thick epi-film samples were grown on c-plane sapphire substrates. The optical and structural characteristics of AlN films are meticulously examined by using high-resolution X-ray diffraction (HR-XRD), scanning electron microscopy (SEM), a dual-beam ultraviolet-visible spectrophotometer, and spectroscopic ellipsometry (SE).

UFO-Net: A Linear Attention-Based Network for Point Cloud Classification.

Three-dimensional point cloud classification tasks have been a hot topic in recent years. Most existing point cloud processing frameworks lack context-aware features due to the deficiency of sufficient local feature extraction information. Therefore, we designed an augmented sampling and grouping module to efficiently obtain fine-grained features from the original point cloud.

Performance Optimization of PbLaScTaTiO Ceramics by Annealing Process.

The annealing effects on PbLaScTaTiO (PLSTT) ceramics prepared by the solid-state reaction method are systemically investigated using experimental and theoretical techniques. Comprehensive studies are performed on the PLSTT samples by varying annealing time (AT) from (=0, 10, 20, 30, 40, 50 and 60) h. The properties involving ferroelectric polarization (FP), electrocaloric (EC) effect, energy harvesting performance (EHP) and energy storage performance (ESP) are reported, compared and contrasted.

The Spatial Correlation and Anisotropy of β-(AlGa)O Single Crystal.

The long-range crystallographic order and anisotropy in β-(AlGa)O (x = 0.0, 0.06, 0.

Enhancing the Output Performance of a Triboelectric Nanogenerator Based on Modified Polyimide and Sandwich-Structured Nanocomposite Film.

Recently, scientists have been facing major obstacles in terms of improving the performances of dielectric materials for triboelectric nanogenerators. The triboelectric nanogenerator (TENG) is one of the first green energy technologies that can convert random mechanical kinetic energy into electricity. The surface charge density of TENGs is a critical factor speeding up their commercialization, so it is important to explore unique methods to increase the surface charge density.

Structural, Surface and Optical Studies of m- and c-Face AlN Crystals Grown by Physical Vapor Transport Method.

Bulk aluminum nitride (AlN) crystals with different polarities were grown by physical vapor transport (PVT). The structural, surface, and optical properties of m-plane and c-plane AlN crystals were comparatively studied by using high-resolution X-ray diffraction (HR-XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Temperature-dependent Raman measurements showed that the Raman shift and the full width at half maximum (FWHM) of the E (high) phonon mode of the m-plane AlN crystal were larger than those of the c-plane AlN crystal, which would be correlated with the residual stress and defects in the AlN samples, respectively.

Angle-Dependent Raman Scattering Studies on Anisotropic Properties of Crystalline Hexagonal 4H-SiC.

Raman scattering spectroscopy (RSS) has the merits of non-destructiveness, fast analysis, and identification of SiC polytype materials. By way of angle-dependent Raman scattering (ADRS), the isotropic characteristics are confirmed for c-face 4H-SiC, while the anisotropic properties of a-face 4H-SiC are revealed and studied in detail via combined experiments and theoretical calculation. The variation functional relationship of the angle between the incident laser polarization direction and the parallel (perpendicular) polarization direction was well established.

An Internal-Electrostatic-Field-Boosted Self-Powered Ultraviolet Photodetector.

Self-powered photodetectors are of significance for the development of low-energy-consumption and environment-friendly Internet of Things. The performance of semiconductor-based self-powered photodetectors is limited by the low quality of junctions. Here, a novel strategy was proposed for developing high-performance self-powered photodetectors with boosted electrostatic potential.

Self-Powered Resistance-Switching Properties of PrCaMnO Film Driven by Triboelectric Nanogenerator.

As one of the promising non-volatile memories (NVMs), resistive random access memory (RRAM) has attracted extensive attention. Conventional RRAM is deeply dependent on external power to induce resistance-switching, which restricts its applications. In this work, we have developed a self-powered RRAM that consists of a PrCaMnO (PCMO) film and a triboelectric nanogenerator (TENG).

Interferometrical single-molecule localization based on dynamic PSF engineering: publisher's note.

This publisher's note contains a correction to Opt. Lett.47, 1770 (2022)10.

Interferometrical single-molecule localization based on dynamic PSF engineering.

We present a method for interferometric single-molecule localization based on dynamic point spread function (PSF) engineering. By using two galvo mirrors, a hexagonal PSF is constructed and the fluorescent signal under different illumination patterns could be acquired simultaneously. This method was evaluated using simulation, fluorescent nanosphere imaging, and single-molecule imaging.

Alternate-Layered MXene Composite Film-Based Triboelectric Nanogenerator with Enhanced Electrical Performance.

The output power of the triboelectric nanogenerator (TENG) strongly depends on the performance of triboelectric materials, especially microstructures and functional groups of them. In this work, aiming at the excellent triboelectric ability, alternate-layered MXene composite films-based TENG with abundant fluorine groups(-F) through layer-by-layer stacking are designed and fabricated. Benefitting from the uniform intrinsic microstructure and increased dielectric constant, when the amount of the NbCT nanosheets increases to 15 wt%, the TENG based on NbCT/TiCT composite nanosheets films achieves the maximum output.

A Polymeric Bilayer Multi-Legged Soft Millirobot with Dual Actuation and Humidity Sensing.

There are numerous works that report wirelessly controlling the locomotion of soft robots through a single actuation method of light or magnetism. However, coupling multiple driving modes to improve the mobility of robots is still in its infancy. Here, we present a soft multi-legged millirobot that can move, climb a slope, swim and detect a signal by near-infrared irradiation (NIR) light or magnetic field dual actuation.

Dielectric and energy storage properties of BiO-BO-SiO doped BaCaZrTiO lead-free glass-ceramics.

A sol-gel method is employed for preparing high quality lead-free glass-ceramic samples (1 - )BCZT-BBS-incorporating BaCaZrTiO (BCZT) powder and BiO-BO-SiO (BBS) glass-doped additives with different values of ( = 0, 0.05, 0.1, 0.

Low-angle optical vortex coronagraphic scatterometer.

The important, but difficult-to-measure zero and low-angle scattering spectrum, as well as the broader angular spectrum, was obtained by use of an optical vortex coronagraphic scatterometer (patent pending). The experimental measurements agreed well with the predictions from the Mie scattering theory. High contrast discrimination allowed us to remove the unscattered coherent illumination, revealing a low-angle superimposed scattered signal.