In the growth of InGaN/GaN multiple quantum well (MQW) structures, a novel defect (called “V-defect”) initiates at threading dislocations in one first wells MQW stack. This is common to almost all InGaN heterostructures. The nature V-defect was evaluated using transmission electron microscopy (TEM), scanning TEM (STEM), and low-temperature cathodoluminescence (CL) on series In0.20Ga0.80N/GaN samples. structure includes buried side-wall (on {101̄1} planes) an open hexagonal inverted pyramid...

Defect structures were investigated by transmission electron microscopy for GaN/Al2O3 (0001) epilayers grown metal-organic chemical vapor deposition using a two-step process. The defect structures, including threading dislocations, partial dislocation bounding stacking faults, and inversion domains, analyzed diffraction contrast, high-resolution imaging, convergent beam diffraction. GaN film growth was initiated at 600 °C with nominal 20 nm nucleation layer. This followed high-temperature...

The structural evolution of epitaxial GaN layers grown on basal plane sapphire has been studied by atomic force microscopy (AFM), x-ray diffraction, and transmission electron (TEM). High-temperature growth (1050–1080 °C) optimized nucleation leads to clear, specular films. AFM the as-grown surface shows evenly spaced monatomic steps indicative layer growth. measurements show a step termination density 1.7×108 cm−2 for 5 μm This value is in close agreement with TEM screw mixed screw-edge...

The structure and morphology of low growth temperature GaN nucleation layers have been studied using atomic force microscopy (AFM), reflection high energy electron diffraction (RHEED), transmission (TEM). were grown at 600 °C by atmospheric pressure metalorganic chemical vapor deposition (MOCVD) on c-plane sapphire. consist predominantly cubic (c-GaN) with a density stacking faults twins parallel to the film/substrate interface. average grain size increases increasing layer thickness during...

The production of biodiesel from plant oil was catalyzed by a magnetic Na₂SiO₃@Ni/C catalyst, and H₂ given off the deactivated catalyst by-product glycerol.

The evolution of morphology and associated extended defects in GaN thin films grown on sapphire by metalorganic chemical vapor deposition (MOCVD) are shown to depend strongly the growth environment. For commonly used two-step process, a change parameter such as reactor pressure influences initial high temperature (HT) mechanism. By means transmission electron microscopy (TEM), atomic force (AFM), resolution X-ray diffraction (HRXRD) measurements, it is that density HT islands nucleation...

The structural and morphological evolution of GaN films grown by MOCVD at high temperature (1080°C) on a low nucleation layer (NL) (0001) sapphire were studied using atomic force microscopy (AFM), transmission electron (TEM) photoluminescence (PL) measurements. (HT) layers found to grow initially forming isolated truncated hexagonal islands having {10*BAR*1*BAR*1} facet planes top plane. non-wetting or partial wetting behavior the HT NL is attributed both roughness predominantly cubic nature NL.

Abstract In current research, the reflection and absorption characteristics of optical switches in systems are often limited by material's response speed tunable range. We propose a novel metal grating structure with phase-change material to overcome these limitations. This paper proposes ultrafast terahertz switch based on vanadium dioxide (VO₂), composed VO₂ layer, dielectric metal, layer located top plasmonic (Au) thin film. The performance variations different states revealed analyzing...

With the acceleration of population aging, it becomes increasingly difficult to meet complex needs older adults living in communities. Although volunteering is an important resource addressing aging crisis, lack clear motivations and finely-tuned strategic guidance present obstacles. This study aims understand strategies involved voluntary service for urban home-based provided by volunteers with a nursing background. A qualitative descriptive design was adopted. Twenty-three background were...

The early stages of hydride vapor phase epitaxy (HVPE) GaN on sapphire were studied using atomic force microscopy, field-emission scanning electron cross-sectional transmission and x-ray diffraction rocking curves. At the high growth rate used (∼33 nm/s), films appear to be fully coalesced for periods as short 1 s. A distinct surface subsequent bulk transformation observed, resulting in significantly smoother film surfaces improved morphology. thick (i.e., 300 μm) HVPE offers a promising...

Hypoxic pulmonary hypertension (HPH) is a progressive and irreversible disease that reduces survival. Echinacoside phenylethanoid glycoside from Tibetan herbs known for its vasorelaxant effect inhibiting the proliferation of rat arterial smooth muscle cells. This study aimed to investigate echinacoside on HPH. Sprague Dawley rats were housed in hypobaric hypoxia chamber (4500 m) 28 days obtain HPH model. (3.75, 7.5, 15, 30 40 mg/kg) was administered by intraperitoneal injection 1st 28th day....

In view of the fact that partial discharge (PD) signal energy is mainly concentrated below hundreds megahertz, ultra-high frequency part weak, and interior space switchgear narrow, this paper proposes a new method for PD detection based on near-field detection. Firstly, principle PD, field characteristics in are analyzed. After that, probe designed with an electric small loop structure. Based its equivalent circuit, measurement amplitude The influence size material obtained by using...

The growth of epitaxial MgO films on Sb-passivated (001)GaAs using pulsed laser deposition has been investigated. temperature at which the Sb-passivation layer was desorbed found to have a significant effect interfacial properties MgO/GaAs heterostructures. Heating substrates 350–380 °C in vacuum resulted (1×3) GaAs surface reconstruction suitable for films. However, residual Sb persist temperatures as high 500 °C. after desorption nonuniform varied thickness from ∼0.1 1.5 nm, whereas heated...

In these studies, we have investigated the role of low-temperature growth in reduction threading dislocation (TD) densities large mismatch heteroepitaxy. Low- and high-temperature (LT) (HT) GaAs growths on highly mismatched substrates were used to find mechanism enhanced TD LT grown (250 °C) GaAs. templates symmetric (equal) subdensities {111}A {111}B planes, whereas HT asymmetric subdensities. A model based reactions was applied experimental results confirmed beneficial reduction....

Basal plane sapphire is a common substrate for the heteroepitaxy of GaN. This presents challenge fabrication cleaved-facet GaN lasers because natural cleavage planes in (0001) α-Al2O3 are not perpendicular to wafer surface. letter describes method achieving cleaved facets through fusion that can potentially be used fabricate based in-plane lasers. We demonstrate successful InP without voids or oxide at interface and optically flat parallel crystallographic host InP. I–V measurements have...

The spatial distribution and atomic mobility of Li ions in the solid solution system Li1-xNb1-xWxO3 (0 ≤ x 0.5) have been studied using solid-state NMR techniques. To maintain charge balance, for each tungsten atom substituting on a niobium site, lithium vacancy is produced sublattice. 6Li magic angle spinning experiments reveal multiple sites, attributed to distributions neighbors. Dipolar 7Li second moments measured at low temperature (−100 °C) depend linearly content, consistent with...

Interface microstructure and strain relaxation of atomic-layer-epitaxy-grown CdSe on ZnSe/GaAs〈001〉 was investigated by using transmission electron microscopy high-resolution techniques. The epilayer is characterized with fluctuated misorientations along the interface, irregularly distributed stacking faults (SFs), an array misfit dislocations (MDs) composed 60°, Lomer, partial types. It found that misorientation related to proportion different 60° MDs SFs, this causes local difference....

We demonstrate a two-step process wherein the lateral epitaxial growth (LEO) of GaN from <10 0>-oriented stripes is initiated at low V/III ratio to produce smooth, vertical <11 0> sidewalls, and where subsequently raised in order increase rate. find that formation <1 01> facets inhibited using this process, it possible maintain sidewalls while achieving large The rate has been increased by up factor 2.6 approach relative identical conditions without initiation ratio. effect...