Luminescent Amorphous Silicon Oxynitride Systems: High Quantum Efficiencies in the Visible Range.

In recent years, researchers have placed great importance on the use of silicon (Si)-related materials as efficient light sources for the purpose of realizing Si-based monolithic optoelectronic integration. Previous works were mostly focused on Si nanostructured materials, and, so far, exciting results from Si-based compounds are still lacking. In this paper, we have systematically demonstrated the high photoluminescence external quantum efficiency (PL EQE) and internal quantum efficiency (PL IQE) of amorphous silicon oxynitride (a-SiNxOy) systems. Within an integration sphere, we directly measured the PL EQE values of a-SiNxOy, which ranged from approximately 2% to 10% in the visible range at room temperature. Then, we calculated the related PL IQE through temperature-dependent PL measurements. The obtained PL IQE values (~84% at 480 nm emission peak wavelength) were very high compared with those of reported Si-based luminescent thin films. We also calculated the temperature-dependent PL EQE values of a-SiNxOy systems, and discussed the related PL mechanisms.

A comparative study of interfacial thermal conductance between metal and semiconductor.

To understand and control thermal conductance of interface between metal and semiconductor has now become a crucial task for the thermal design and management of nano-electronic and micro-electronic devices. The interfacial alignments and electronic characteristics of the interfaces between metal and semiconductor are studied using a first-principles calculation based on hybrid density functional theory. The thermal conductance of interfaces between metal and semiconductor were calculated and analyzed using diffuse mismatch model, acoustic mismatch model and nonequilibrium molecular dynamics methods. Especially, according to nonequilibrium molecular dynamics, the values of thermal conductance were obtained to be 32.55 MW m-2 K-1 and 341.87 MW m-2 K-1 at C-Cu and Si-Cu interfaces, respectively. These results of theoretical simulation calculations are basically consistent with the current experimental data, which indicates that phonon-phonon interaction play a more important role than electron-phonon interaction during heat transport. It may be effective way to improve the interfacial thermal conductance through enhancing the interface coupling strength at the metal-semiconductor interface because the strong interfacial scattering plays a role in suppressing in the weaker interface coupling heterostructure, leading to the lower thermal conductance of interfaces. This could provide a beneficial reference for the design of the Schottky diode and thermal management at the interfaces between metal and semiconductor.

High photoluminescence quantum yields generated from N-Si-O bonding states in amorphous silicon oxynitride films: erratum.

We present an erratum to our paper [Opt. Express2631617 (2018)10.1364/OE.26.031617OPEXFF1094-4087]. Due to the statistical requirements of the postdoctoral outbound assessment, the first organization of the research articles must be "Nanjing University". As all our experimental data in this article is done in the laboratory of Nanjing University, so "Nanjing University" should be used as the first organization to meet the appraisal requirements of the postdoctoral workstation.

A New Design of a CMOS Vertical Hall Sensor with a Low Offset.

Vertical Hall sensors (VHSs), compatible with complementary metal oxide semiconductor (CMOS) technology, are used to detect magnetic fields in the plane of the sensor. In previous studies, their performance was limited by a large offset. This paper reports on a novel CMOS seven-contact VHS (7CVHS), which is formed by adding two additional contacts to a traditional five-contact VHS (5CVHS) to alleviate the offset. The offset voltage and offset magnetic field of the 7CVHS are reduced by 90.20% and 88.31% of those of the 5CVHS, respectively, with a 16.16% current-related sensitivity loss. Moreover, the size and positions of the contacts are optimized in standard GLOBALFOUNDRIES 0.18 µm BCDliteTM technology by scanning parameters using FEM simulations. The simulation data are analyzed in groups to study the influence of the size and contact positions on the current-related sensitivity, offset voltage, and offset magnetic field.

Acid-Catalyzed Water Extraction of Two Polysaccharides from Artemisia argyi and Their Physicochemical Properties and Antioxidant Activities.

In this study, two purified polysaccharide fractions, Artp1 and Artp2, were obtained using acid-catalyzed water extraction, and then purified by DEAE-52 cellulose and Sephadex G-200 column chromatography from the crude polysaccharides of Artemisia argyi. Their physicochemical properties were investigated by gel permeation chromatography (GPC), high-performance anion exchange chromatography (HPAEC), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), thermal analysis, and methylation analysis. The average molecular weight (Mw) of Artp1 and Artp2 were estimated to be 42.17 kDa and 175.22 kDa, respectively. Monosaccharide composition analysis revealed that the Rha, Gal, and GalA occupied main proportion in Artp1 with the molar ratio of 25.1:24.7:40.4, while the Rha, Gal, Xly, and GalA occupied the main proportion in Artp2 with the molar ratio of 16.7:13.5:12.8:38.7. Due to the high yield and the relatively high carbohydrate content, the Artp1 was determined by the methylation analysis and NMR. The results of Artp1 indicated that 1,4-GalpA and 1,2,4-Rhap formed the backbone with some 1,2-Rhap, 1,3-Galp, and 1,6-Galp in the backbone or the side chains. Artp1 and Artp2 exhibited effective antioxidant activities by DPPH radical scavenging assay and hydroxyl radical scavenging assay in a dose-dependent manner. These investigations of the polysaccharides from A. argyi. provide a scientific basis for the uses of Artp1 and Artp2 as ingredients in functional foods and medicines.

Physicochemical properties and bioactivities of original and Se-enriched polysaccharides with different molecular weights extracted from Pleurotus ostreatus.

Three polysaccharides (WZP1, WZP2, WZP3) and their Se-enriched products (SeWZP1, SeWZP2 and SeWZP3) were obtained from Pleurotus ostreatus using a simple, rapid method and HNO3-Na2SeO3 method, respectively. The molecular weight distribution profiles of all samples except SeWZP2 showed double peaks. The average molecular weights (Mw) of WZP1-3 were 48.6 kDa, 20.2 kDa and 11.8 kDa, respectively, and of SeWZP1-3 were 19.6 kDa, 37.7 kDa, 14.5 kDa, respectively. The complexity of monosaccharide composition of WZP1-3 was inversely proportional to the ethanol concentration used in the ethanol precipitation process. Additionally, the results of biological activity tests indicated that α-glucosidase inhibitory activity of WZP1-3 was related to the molecular weight and the monosaccharide composition complexity. The selenized modification can improve the α-glucosidase-inhibiting, hydroxyl radical-scavenging activity of P. ostreatus polysaccharides. Therefore, by improving their bioactivities by selenization, the polysaccharides of P. ostreatus could be utilized as a natural health food supplement.

Influences of Extraction Methods on Physicochemical and Functional Characteristics of Three New Bulbil Starches from Dioscorea opposita Thunb. cv. Tiegun.

Starches from the bulbils of Dioscoreae opposita Thunb. cv. Tiegun were isolated by aqueous steeping (SBS), enzyme extraction (EBS), and alkaline extraction (ABS) methods, respectively. The physicochemical, mineral composition, thermal and morphological characteristics of these starches were investigated. The starch granules were oval, spherical and kidney-shaped and its crystal type is a mixture of A-type and B-type patterns. The starches having larger average granule size showed more amylose and phosphorus contents than those with smaller average granule size. Differential scanning calorimetry (DSC) showed that the SBS had an endothermic transition ranging from 65.8 °C to 76.3 °C with an enthalpy of 2.0 J/g. The endothermic transitions of ABS and EBS showed the regions of 67.9 °C to 73.0 °C, and 66.8 °C to 82.0 °C, respectively. The gelationization enthalpies of ABS and EBS were 13.8 and 11.5 J/g, respectively. Additionally, ABS presented greater clarity in comparison with EBS and SBS. Pasting properties indicated that ABS had the highest peak viscosity, breakdown, but SBS had the lowest trough, final viscosity, setback, and pasting temperature. Generally, ABS and EBS could be used as food thickener or frozen food additives. SBS and EBS were potential technological alternatives in quality preservation of frozen starch-based products and other industrial applications.

Chinese quince seed gum: Flow behaviour, thixotropy and viscoelasticity.

Characterization of the rheological properties of Chinese quince seed gum (CQSG) is fundamental when using it in food production. In the present paper, the chemical compositions and the rheological properties of CQSG at different concentrations, types of salts, temperatures and pH values were characterized by using shear or dynamic rheological experiments. The results demonstrated that uronic acid content of CQSG (31.7%) was high and different concentration CQSG solutions presented Newtonian plateaus followed by shear thinning regions. The viscosities of the gum solutions decreased with the addition of any salt, with increase in temperature and at extreme pH values (3 and 11). The stress and frequency sweep tests demonstrated a unique result in that the crossover frequency shifted to a higher value when the CQSG solution concentration increased. It is the basis for CQSG product development and quality control for its potential applications.

Tunable Luminescent A-SiNxOy Films with High Internal Quantum Efficiency and Fast Radiative Recombination Rates.

In this work, we systematically investigated the Nx bonding defects that induced high photoluminescence internal quantum efficiencies (PL IQEs) and very fast radiative recombination processes in amorphous silicon oxynitride (a-SiNxOy) systems. The luminescent N‒Si‒O bonding-related defect states were checked for the XPS, EPR, and temperature-dependent steady-state PL (TD-SSPL) properties. The PL IQEs were calculated from PL quantum yields through the principle of planar geometry optics, and then confirmed by the TD-SSPL properties. The radiative recombination rates [kr(R)] were determined by combining the PL IQE values and ns-PL lifetimes obtained from time-resolved PL measurements. Both the PL IQE, exceeding 72%, and the fast kr(R) (~108 s-1) are proportional to the concentration of Nx defects, which can be explained by N‒Si‒O bonding states related to the quasi-three-level model, suggesting the possible realization of stimulated light emission in a-SiNxOy systems.

Photoluminescence spectra of the Mn2+d-d multiplets transitions of zinc-blende MnTe epitaxial films: laser and deuterium lamp excitation study.

The luminescences of zinc-blende MnTe epitaxial films are respectively excited by a laser and deuterium lamp to study Mn2+d-d multiplets transitions. Besides the inclusion of the band gap, all other excited states related to Mn2+d-d transitions including T14(G4), T24(G4), A14[E4(G4)], T24(D4), E4(D4), and T22(I2) are observed. The shift and broadening of the T14(G4) and T24(G4) lines with increasing temperature are described by the electron-phonon coupling. Step-like energy and intensity shifts for the A14[E4(G4)], T24(D4), E4(D4), and T22(I2) transitions occur in the vicinity of the Néel point, which can be ascribed to the different spin-ordering-induced energy relaxation in ground and excited states of Mn2+d-d multiplets, and these transitions show temperature independence and weak quenching.

High photoluminescence quantum yields generated from N-Si-O bonding states in amorphous silicon oxynitride films.

We investigated the high absolute photoluminescence quantum yields (PL QYs) from tunable luminescent amorphous silicon oxynitride (a-SiNxOy) films. The PL QY of 8.38 percent has been achieved at PL peak energy of 2.55 eV in a-SiNxOy systems, which is higher than those of reported nanocrystal-Si embedded silicon nitride films. The existence of N-Si-O bonding states was confirmed by performing FTIR, XPS and EPR measurements. The PL QY is proportional to the concentration of Nx defects, indicating the dominant contribution of luminescent N-Si-O bonding states in radiative recombination processes. Particularly, we precisely monitored the ns-PL lifetimes evolution profile versus detected emission wavelengths, and further verified that the N-Si-O bonding states are responsible for highly efficient PL.

Nanoscale quantification of charge injection and transportation process in Si-nanocrystal based sandwiched structure.

Si nanocrystals are formed by using KrF pulsed laser crystallization of an amorphous SiC/ultrathin amorphous Si/amorphous SiC sandwiched structure. Electrons and holes are injected into Si nanocrystals via a biased conductive AFM tip and the carrier decay and transportation behaviours at the nanoscale are studied by joint characterization techniques of Kelvin probe force microscopy (KPFM) and conductive atomic force microscopy (CAFM). Quantification of the surface charge density is realized by solving the Poisson equation based on KPFM measurements. Besides, the asymmetric barrier height for electrons and holes is considered to play a dominant role in controlling the charge retention and transportation characteristics. The methodology developed in this work is promising for studying the charge injection and transportation process in other materials and structures at the nanoscale.