Se Te Research Articles

Inkjet printing of mixed layers comprising multinary semiconductor quantum dots and charge transport materials for light‐emitting diode displays

AbstractQuantum dots (QDs) are important luminescent structures with applications in wide‐color‐gamut displays requiring exceptional color reproducibility. Multinary semiconductor QDs are expected to serve as eco‐friendly materials to replace conventional QDs owing to the narrow spectral widths and tunable bandgaps of these QDs. However, the application of multinary QDs, which tend to exhibit defect‐related emissions, to QD light‐emitting diode (QLED) displays will require electroluminescence to be obtained from QLEDs incorporating inkjet‐printed emitting layers. The present work examines QLEDs exhibiting vibrant color emissions based on blue‐emitting Zn–Se–Te QDs, green‐emitting Ag–In–Ga–S QDs, and red‐emitting Ag–Cu–In–Ga–S QDs. Each such QLED contains QD emitting layers comprising a mixture of charge transport materials. The spectra obtained from these RGB QLEDs fabricated by spin‐coating show very high color purity. Passive matrix QLED displays incorporating these QDs are also fabricated by inkjet printing to demonstrate the high color purity that can be obtained from multinary QDs in displays. In conjunction with passive matrix driving, these displays produce clear moving images with vibrant electroluminescence originating from the multinary QDs. The present results indicate that these QDs have significant potential for utilization in wide‐color‐gamut displays.

Your Roots are Showing (Spanish) Se Te Ven Las Raíces

Your Roots are Showing (Spanish) Se Te Ven Las Raíces

New Type of Gold-Bearing Mineralization at the Ozernovskoe Au–Te–Se Epithermal Deposit (Central Kamchatka, Russia)

New Type of Gold-Bearing Mineralization at the Ozernovskoe Au–Te–Se Epithermal Deposit (Central Kamchatka, Russia)

Experimental analysis and ANFIS modeling of optical properties and band gap engineering in Se–Te–Ge film composition and insights into its photonic applications

Experimental analysis and ANFIS modeling of optical properties and band gap engineering in Se–Te–Ge film composition and insights into its photonic applications

Solution-derived Ge–Sb–Se–Te phase-change chalcogenide films

Ge–Sb–Se–Te chalcogenides, namely Se-substituted Ge–Sb–Te, have been developed as an alternative optical phase change material (PCM) with a high figure-of-merit. A need for the integration of such new PCMs onto a variety of photonic platforms has necessitated the development of fabrication processes compatible with diverse material compositions as well as substrates of varying material types, shapes, and sizes. This study explores the application of chemical solution deposition as a method capable of creating conformally coated layers and delves into the resulting modifications in the structural and optical properties of Ge–Sb–Se–Te PCMs. Specifically, we detail the solution-based deposition of Ge–Sb–Se–Te layers and present a comparative analysis with those deposited via thermal evaporation. We also discuss our ongoing endeavor to improve available choice of processing-material combinations and how to realize solution-derived high figure-of-merit optical PCM layers, which will enable a new era for the development of reconfigurable photonic devices.

Features of the optical properties of chalcogenide glassy semiconductor Ge-As-Se(Te) systems

In this work were determined the optical band gap (Eg), packing coefficient (𝜘) and average atomic volume (Va) by conducting experiments to measure the optical transmission spectra and density (ρ) of chalcogenide glassy semiconductors of Ge-As-Se(Te) systems. Reasons of changes occurring in the band gap and in the structure of the amorphous matrix of the studied materials were suggested taking into account existing ideas about the nature of the band energy spectrum of chalcogenide glasses and analysis of experimental data. The dependence of ϰ and Va on Z and R are investigated for stoichiometric compositions of As25Ge12.5Se(Te)62.5 and the nature of these dependencies were explained in detail.

Existence of density inhomogeneity of liquid Te associated with liquid–liquid phase transition

We performed small-angle x-ray scattering measurements of liquid Te using a synchrotron radiation facility and observed maximum scattering intensity near 620 K in the supercooled region (melting temperature 723 K). This indicates that density inhomogeneity exists in liquid Te, and the fact that this temperature coincides with the temperature at which the specific heat, sound velocity, and thermal expansion coefficient reach their maxima means that this density inhomogeneity is the cause of these thermodynamic anomalies. The thermodynamic anomalies in liquid Te had already been shown in the 1980s to be comprehensively explained by the inhomogeneity associated with the continuous liquid–liquid phase transition (LLT), but direct experimental evidence for the existence of the inhomogeneity had not been obtained. The present results, together with those already obtained for mixture systems (Te–Se, Te–Ge), indicate the existence of inhomogeneity associated with LLT in liquid Te systems, and strongly support the model. Recently, similar maximum scattering intensity has also been observed in supercooled liquid water, which exhibits thermodynamic anomalies similar to those of Te, indicating the universality of the inhomogeneous model or LLT scenario to explain the thermodynamics of such ‘anomalous liquids’. Further development of the LLT scenario is expected in near future.

Peculiarities of Electrical Switching and Phase Transition Dynamics in Bismuth-Infused Se–Te Chalcogenide Glasses: From Bulk to Thin Film Devices

Peculiarities of Electrical Switching and Phase Transition Dynamics in Bismuth-Infused Se–Te Chalcogenide Glasses: From Bulk to Thin Film Devices

Optical and Glass Stability Parameters of Ge–Te–Se–Sb Chalcogenide Glasses for Optical Data Storage

Optical and Glass Stability Parameters of Ge–Te–Se–Sb Chalcogenide Glasses for Optical Data Storage

How to repair the performance degradation of WSeTe SBFET caused by channel vacancy defects: A first principles study

The QuantumATK software package based on density functional theory and non-equilibrium Green's function is used to predict the performance of a 5.1 nm in-plane contact double-gate WSeTe Schottky barrier SBFET with 1 T-WTe2 as electrodes and Janus WSeTe as channel. It is found that the performance of 5.1 nm WSeTe SBFET meets the prediction parameters of ITRS(2013 version) about high performanc device for the production year 2028, but Te (Se) vacancy defect at the channel near the source will degrade its performance. How to repair the performance of the WSeTe SBFET with Te (Se) vacancy defect at the channel near the source? The effects of O, Cl and N passivation of Te (Se) vacancy defects on the performance of WSeTe SBFET were discussed. The results indicate that O Passivation can repair and even improve the performance of WSeTe SBFET by repairing the DOS changes of monolayer WSeTe induced by Te (Se) vacancy defects.

Janus molybdenum di-chalcogenides based van der Waals bilayers for supercapacitor electrode design- effects of interlayer stacking orientations on quantum capacitance

In this work, for the first time, the quantum capacitance of an artificial two-dimensional (2D) material system based on van der Waals (vdW) bilayer heterostructures of Janus Molybdenum Di-chalcogenides, MoXY (X≠Y, X/YS, Se, Te) have been extensively investigated for electrode design of electrical double-layer (EDL) supercapacitor. The effects of different interlayer stacking orientations on local charge distribution, interlayer charge transfer, energy band structure, and density of states (DOS) have been comprehensively analyzed and correlated with the excess charge density and quantum capacitance variation with local electrode potential. Furthermore, the total capacitance reduction with respect to EDL capacitance has been analyzed over a wide range of EDL capacitance, and the performance of vdW Janus bilayers has been systematically benchmarked against the natural monolayers/bilayers and Janus monolayers of Molybdenum Di-chalcogenides. The results demonstrate that the large interlayer charge transfer induced built-in interlayer electric field significantly reduces the energy band gap of vdW Janus bilayers for S–Te and Se–Te interlayer stacking, thus leading to a significantly superior quantum capacitance. Finally, the favorable valley-dependent effective mass and band-degeneracy in MoSTe/MoSeTe have greatly enhanced quantum capacitance in S–Te and Se–Te stacking, rendering these bilayers a highly attractive candidate for supercapacitor electrode design.

A thermo-physical study of In additive Se–Te chalcogenide glasses

A thermo-physical study of In additive Se–Te chalcogenide glasses

Phenomenology of M–N rule and high-field conduction in Ge–Te–Se–Sc rare-earth doped glasses

Phenomenology of M–N rule and high-field conduction in Ge–Te–Se–Sc rare-earth doped glasses

Exploring the Structure and Properties of VwSeyTe2−y Mixed Crystals in the VTe2–VSe2 System

Vanadium (IV) chalcogenide materials are of increasing interest for use in catalysis and energy conversion-related applications. Since no ternary compounds are yet known in the V–Se–Te system, we studied ternary VwSeyTe2−y (w = 1.10, 1.13; y = 0.42, 0.72) phases crystallizing in space group P3¯m1 (no. 164). Two single-crystal specimens with differing compositions of a solid solution were obtained using the ceramic method. All products were characterized by either single-crystal or powder X-ray diffraction. The lattice parameters increase with rising tellurium content in accordance with the larger ionic radius of the tellurium anion compared to selenium. The chemical compositions were confirmed by energy-dispersive X-ray spectroscopy. Furthermore, magnetic measurements mostly revealed antiferromagnetic properties. Simultaneous differential scanning calorimetry/thermogravimetric analyses in a nitrogen atmosphere showed endothermic decomposition accompanied by the formation of VN. The decomposition of VSe and VTe was observed in an argon atmosphere. The results of this work can serve as a basis for the synthesis of new phases in the V–Se–Te and related vanadium chalcogenide systems.

Thermally processed phase change behavior on the stoichiometric efficacy of quaternary Se77.5-X Te20 Sn2.5 AgX (X = 2.5, 5, 7.5) thin films

Thin films of the quaternary metal chalcogenide have recently gained attention due to their improved electrical, optical, thermal, and structural properties. The structural, thermal, morphological, optical, and electrical properties of Ag-modified novel quaternary Se–Te–Sn–Ag thin film systems are investigated in this paper. Temperature-dependent structural, electrical, and thermoelectric properties are given special attention. From Differential Thermal Analysis/Thermogravimetric Analysis (DTA/TGA), the Ag content in this composition induces thermal stability and crystalline phase as well as glass phase transitions. High-temperature X-ray diffraction (HTXRD) patterns were used to investigate the temperature-dependent structural phase transition, grain size, lattice strain, and dislocation density. The morphological observations show that Ag concentration promotes the nucleation and growth processes of nanorod structures in as-deposited thin films. Optical characteristics reveal higher IR transparency in thin films and high refractive indexes in the range of 3.22–3.29. The as-deposited thin films resistivity decreases with increasing temperature and silver content. The Hall measurement corroborates the results obtained from the Seebeck measurements, indicating that the samples are n-type. The phase change switching mechanism of phase change devices is still unclear; there are two possible mechanisms: thermal and electronic models. This work proposes thermally processed phase transition behaviors in structural and electrical studies. The result of the above analyses shows that the quaternary Se–Te–Sn–Ag thin film will be a potential candidate for phase change device applications.

Enhanced ferromagnetism, magnetic anisotropy, and spin polarization in Janus CrSeTe via strain and doping

Recently, experimental 2D magnetic CrSe2 and CrTe2 inspired the study on their Janus CrSeTe, which breaks the mirror symmetry of Cr–Se(Te)–Cr. However, the CrSeTe monolayer possesses a lower Curie temperature and the in-plane magnetic anisotropy, and few works concerned both its zigzag- and stripy-antiferromagnetic states, which are crucial to determine the magnetic ground state and magnetic transition temperature. In this Letter, using first-principles calculations and Monte Carlo simulations, we systematically explore the strain, carrier-doping, and electric field effects on magnetic and electronic properties of monolayer CrSeTe. We demonstrate that monolayer CrSeTe preserves ferromagnetism in a large range of whether strain or doping. The estimated Curie temperature can be increased from 167 K to the room-temperature by the combination of 4% tensile strain and 0.1 e doping due to the enhanced ferromagnetic Cr–Se(Te)–Cr super-exchange interaction. Interestingly, either a small tensile strain (1%) or a low hole doping (0.025 h) can induce the transition of the easy axis from in-plane to out-of-plane due to the increased out-of-plane magnetic anisotropy from hybridized pz and py orbitals of Te atoms. In addition, the spin polarization is improved by over 60% by the tensile strain. Our results suggest that small strain and low carrier-doping induced room-temperature ferromagnetism, large out-of-plane magnetic anisotropy, and high spin polarization make CrSeTe useful in 2D spintronic applications and will stimulate broad studies on the regulation of magnetic and electronic properties of this class of magnetic Janus monolayers.

Influence of Te replacement by Bi in In10Se70Te20-xBix films and its structural, optical, morphological, surface wettability and thermal behaviors for optoelectronic applications

The current investigation is based on Bi doping into In–Se–Te alloy and its impact on the surface morphology, structure, and optical behaviors. The transition from In10Se70Te20 to In10Se70Bi20 composition modified its structural phases as observed from X-ray diffraction study. The crystallite size increased from 9.55 nm to 14.04 nm. The lattice strain decreased from 0.0234 to 0.0106 with Bi content. Raman study infers the microstructural and phase formation in the films. The structure change is associated with change in surface morphology as noticed from field emission scanning electron microscopy images. The composition of In10Se70Te20-xBix (x = 0, 5, 10, 15, 20 at %) films were observed from energy dispersive X-ray analysis. The UV–Vis–NIR data showed the decrease in transmittance from 80 % to 10 % at 2100 nm wavelength with Bi%. The decrease in direct bandgap from 1.64 eV to 1.37 eV was discussed by Davis-Mott model for density of defect states. The increase in Urbach energy from 101 meV to 161 meV is based on the transition from In10Se70Te20 to In10Se70Bi20 composition. The optical parameters like optical density, extinction coefficient and absorption coefficient were increased with Bi addition. The calculated static linear refractive index by different model at different Bi% satisfies Moss's relation. The enhanced non-linear susceptibility from 2.96 × 10−10 esu to 3.33 × 10−10 esu and non-linear refractive index from 1.58 × 10−7 esu to 1.86 × 10−7 esu with Te replacement by Bi may be suitable for non-linear optical devices. The change in different theoretically calculated physical parameters were found to be in accordance with the experimental data. The surface wettability study showed the transition from hydrophilic to hydrophobic nature with increase in Bi %. The obtained experimental results for the films may be used for various photonic and optoelectronic device applications.

A Comprehensive Evaluation on the Performances of China’s Information Technology Characteristic Towns Utilizing the Advantage-Oriented Competitive Evaluation (ACE) Method

The characteristic town (CT, or Te Se Xiao Zhen in Chinese) program is among the most important drivers of China’s new urbanization. However, the program aroused countrywide concerns about its rapid elevation, excessive real estate construction, high investment risk, and severe construction homogenization. Despite the policy’s rapid dissemination, there needs to be a theoretical basis and practical guidance for the local government to evaluate CT candidates to ensure the feasibility and sustainability of this novel urbanization practice. Moreover, simply employing traditional evaluation techniques, such as TOPSIS or analytical hierarchical process, may overwhelmingly stress inherited advantages of existing towns and easily overlook the potential candidates in the policy’s early implementation. Thus, the current study employs a novel advantage-oriented competitive evaluation (ACE) approach, which values the comparative advantages of the evaluated objects, to rate the performance of fifteen information technology characteristic towns (ITCTs) comprehensively. The presented work constructs a three-level performance index system based on public statistics, comprehensively evaluates the ITCTs’ performance, and reveals each CT’s unique advantages. The analysis and discussion disclose the evaluated ITCTs’ development status, highlighting the blooming development against public concerns and the ITCTs’ clustering based on unique comparative advantages. The evaluation results also verify that the ACE is an excellent comprehensive evaluation approach that can reveal an object’s comparative advantages from varying facets and depths. Finally, this work briefly concludes the emerging issues of ITCTs’ construction, the limitations of ACE evaluation, and suggestions for future research.

Review: tunable nanophotonic metastructures.

Tunable nanophotonic metastructures offer new capabilities in computing, networking, and imaging by providing reconfigurability in computer interconnect topologies, new optical information processing capabilities, optical network switching, and image processing. Depending on the materials and the nanostructures employed in the nanophotonic metastructure devices, various tuning mechanisms can be employed. They include thermo-optical, electro-optical (e.g. Pockels and Kerr effects), magneto-optical, ionic-optical, piezo-optical, mechano-optical (deformation in MEMS or NEMS), and phase-change mechanisms. Such mechanisms can alter the real and/or imaginary parts of the optical susceptibility tensors, leading to tuning of the optical characteristics. In particular, tunable nanophotonic metastructures with relatively large tuning strengths (e.g. large changes in the refractive index) can lead to particularly useful device applications. This paper reviews various tunable nanophotonic metastructures' tuning mechanisms, tuning characteristics, tuning speeds, and non-volatility. Among the reviewed tunable nanophotonic metastructures, some of the phase-change-mechanisms offer relatively large index change magnitude while offering non-volatility. In particular, Ge-Sb-Se-Te (GSST) and vanadium dioxide (VO2) materials are popular for this reason. Mechanically tunable nanophotonic metastructures offer relatively small changes in the optical losses while offering large index changes. Electro-optically tunable nanophotonic metastructures offer relatively fast tuning speeds while achieving relatively small index changes. Thermo-optically tunable nanophotonic metastructures offer nearly zero changes in optical losses while realizing modest changes in optical index at the expense of relatively large power consumption. Magneto-optically tunable nanophotonic metastructures offer non-reciprocal optical index changes that can be induced by changing the magnetic field strengths or directions. Tunable nanophotonic metastructures can find a very wide range of applications including imaging, computing, communications, and sensing. Practical commercial deployments of these technologies will require scalable, repeatable, and high-yield manufacturing. Most of these technology demonstrations required specialized nanofabrication tools such as e-beam lithography on relatively small fractional areas of semiconductor wafers, however, with advanced CMOS fabrication and heterogeneous integration techniques deployed for photonics, scalable and practical wafer-scale fabrication of tunable nanophotonic metastructures should be on the horizon, driven by strong interests from multiple application areas.

Simultaneous bioreduction of tellurite and selenite by Yarrowia lipolytica, Trichosporon cutaneum, and their co-culture along with characterization of biosynthesized Te–Se nanoparticles

BackgroundNatural and anthropogenic activities, such as weathering of rocks and industrial processes, result in the release of toxic oxyanions such as selenium (Se) and tellurium (Te) into the environment. Due to the high toxicity of these compounds, their removal from the environment is vital.ResultsIn this study, two yeast strains, Yarrowia lipolytica and Trichosporon cutaneum, were selected as the superior strains for the bioremediation of tellurium and selenium. The reduction analyses showed that exposure to selenite induced more detrimental effects on the strains compared to tellurite. In addition, co-reduction of pollutants displayed almost the same results in selenite reduction and more than ~ 20% higher tellurite reduction in 50 h, which shows that selenite triggered higher tellurite reduction in both strains. The selenite and tellurite kinetics of removal were consistent with the first-order model because of their inhibitory behavior. The result of several characterization experiments, such as FE-SEM (Field emission scanning electron microscopy), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), and dispersive X-ray (EDX) on Te–Se nanoparticles (NPs) revealed that the separated Te–Se NPs were needle-like, spherical, and amorphous, consisted of Te–Se NPs ranging from 25 to 171 nm in size, and their surface was covered with different biomolecules.ConclusionsRemarkably, this work shows, for the first time, the simultaneous bioreduction of tellurite and selenite and the production of Te–Se NPs using yeast strains, indicating their potential in this area, which may be applied to the nanotechnology industry and environmental remediation.Graphical