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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Plasma Preparation of the Top-Quality Phase Change Materials Based on As-Se-Te Chalcogenide System
摘要： The excellence of the Plasma-Enhanced Chemical Vapor Deposition (PECVD) approach in terms of preparation of the top-quality phase change materials based on As-Se-Te chalcogenide ternary system has been demonstrated. The samples were synthesized via direct interaction of arsenic, selenium and tellurium vapors into low-temperature non-equilibrium RF (40 MHz) plasma discharge at low pressure. The amorphous films with high degree of structural and chemical uniformity have been prepared in the broad range of contents, in particular, the chemical compositions going beyond the region of glass formation.
关键词： PECVD,chalcogenide films,phase change materials
更新于2025-09-09 09:28:46
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Superstructural Ordering in Hexagonal CuInSe2 Nanoparticles
摘要： Chalcogenide semiconducting nanoparticles are promising building blocks for solution-processed fabrication of optoelectronic devices. In this work, we report a new large-scale colloidal synthesis of metastable CuInSe2 nanoparticles with hexagonal plate-like morphology. Powder X-ray diffraction analysis of the nanoparticles showed that the structure of the nanoparticles is not simple hexagonal wurtzite-type CuInSe2 (space group P63mc), indicating the formation of an ordered superstructure. Detailed insight into this structural aspect was explored by high-resolution electron microscopy, and the results evidence an unreported chemical ordering within the synthesized CuInSe2 nanoparticles. Specifically, while the Se sublattice is arranged in perfect wurtzite subcell, Cu and In are segregated over distinct framework positions, forming domains with lower symmetry. The arrangement of these domains within the hexagonal Se substructure proceeds through the formation of a number of planar defects, mainly twins and antiphase boundaries. As a semiconductor, the synthesized material exhibits a direct optical transition at 0.95 eV, which correlate well with its electronic structure assessed by density functional theory calculations. Overall, these findings may inspire the design and synthesis of other nanoparticles featuring unique chemical ordering; thus, providing an additional possibility of tuning intrinsic transport properties.
关键词： hexagonal plate-like morphology,Chalcogenide,CuInSe2,direct optical transition,chemical ordering,semiconducting nanoparticles
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Austin, TX, USA (2018.9.24-2018.9.26)] 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Well-Posed Verilog-A Compact Model for Phase Change Memory
摘要： In this work, we demonstrate a well-posed compact model for phase change memory (PCM) devices based on Ge2Sb2Te5 (GST) chalcogenide. This model supports all modes of simulation including transient, DC, and AC. The model is developed in Verilog-A and simulated using HSPICE. It is computationally simple and successfully captures the key high level behaviors of memory switching, including the resistance dependence on programming voltages, currents and pulse time-scales.
关键词： Verilog-A,chalcogenide,well-posed model,Phase change memory
更新于2025-09-09 09:28:46
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Investigation of the Atomic Structure of Ge-Sb-Se Chalcogenide Glasses
摘要： Glasses with composition of GexSb40-xSe60 (x= 40, 35, 32, 27, 20, 15 at. %) have been synthesized. Neutron and X-ray diffraction techniques were used to study the atomic glassy structure, and Reverse Monte Carlo (RMC) simulations were applied to model the 3-dimensional atomic configurations and thorough mapping of the atomic parameters, such as first and second neighbour distances, coordination numbers, and bond-angle distributions. The results are explained with formation of GeSe4 and SbSe3 structural units, which correlate with the Ge/Sb ratio. For all the studied compositions, the Ge-Se, Sb-Se, Ge-Ge, and Se-Se bonds are significant. RMC simulations reveal the presence of Ge-Sb and Sb-Sb bonds, being dependent on Ge/Sb ratio. All atomic compositions satisfy formal valence requirements, i.e., Ge is fourfold coordinated, Sb is threefold coordinated, and Se is twofold coordinated. By increasing the Sb content, both the Se-Ge-Se bonds angle of 107±3° and Se-Sb-Se bonds angle of 118±3° decrease, respectively, indicating distortion of the structural units. Far infrared Fourier Transform spectroscopic measurements conducted in the range of 50-450 cm-1 of oblique (75°) incidence radiation have revealed clear dependences of the IR band’s shift and intensity on the glassy composition, showing features around x=27 at.% supporting the topological phase transition to a stable rigid network consisting mainly of SbSe3 pyramidal and GeSe4 tetrahedral clusters. These results are in agreement with the Reverse Monte Carlo models, which define the Ge and Sb environment.
关键词： X-ray diffraction,chalcogenide glasses,atomic structure,FTIR spectroscopy,Ge-Sb-Se,neutron diffraction,Reverse Monte Carlo
更新于2025-09-04 15:30:14
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Towards on-chip mid infrared photonic aerosol spectroscopy
摘要： We propose an on-chip mid-infrared (MIR) photonic spectroscopy platform for aerosol characterization to obtain highly discriminatory information on the chemistry of aerosol particles. Sensing of aerosols is crucial for various environmental, climatic, warfare threat detection, and pulmonary healthcare applications. Currently, chemical characterization of aerosols is performed using FTIR spectroscopy, yielding chemical ?ngerprinting because most of the vibrational and rotational transitions of chemical molecules fall in the IR range, and Raman spectroscopy. Both techniques use free space bench-top geometries. Here, we propose miniaturized on-chip MIR photonics-based aerosol spectroscopy consisting of a broadband spiral-waveguide sensor that signi?cantly enhances the particle-light interaction to improve sensitivity. The spiral waveguides are made of a chalcogenide glass material (Ge23Sb7S70) which shows a broad transparency over the IR range (1–10 lm). We demonstrate the sensing of N-methyl aniline-based aerosol particles with the device. We anticipate that the sensor will readily complement existing photonic resonator-based particle sizing and counting techniques to develop a uni?ed framework for on-chip integrated photonic aerosol spectroscopy.
关键词： N-methyl aniline,chalcogenide glass,on-chip mid-infrared photonic spectroscopy,aerosol characterization,spiral-waveguide sensor
更新于2025-09-04 15:30:14
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Ba10Zn7M6Q26: Two New Mid-infrared Nonlinear Optical Crystals with T2 Supertetrahedron 3D Framework
摘要： Two new mid-infrared (MIR) nonlinear optical (NLO) chalcogenide crystals, Ba10Zn7In6S26, 1 and Ba10Zn7Ga6Se26, 2 are discovered by traditional solid state reactions. 1 and 2 are isostructural and they represent a novel three-dimensional (3D) framework made by apexe-sharing T2 supertetrahedron 2D layers that are stacked alternately by another kind of T2 supertetrahedra though sharing apexes along the c direction, with T1 tetrahedra inserting in the tunnels and Ba2+ cations locating both in the voids and tunnels. Among them, 1 shows attractive MIR NLO properties of a wide band gap of 3.0 eV, a strong second harmonic generation (SHG) signal about 4.1 times that of the commercial AgGaS2 at particle sizes of 30–46 μm under a 2.05 μm laser radiation, and a high LDT of 37.2 times that of benchmark AgGaS2 at particle sizes of 150–210 μm under a 1.064 μm laser radiation. This distinguishes 1 as a new promising MIR NLO material. In addition, the density functional theory (DFT) analyses suggest that the SHG response of 1 comes mainly from the electronic transitions from S 3p to Ba 5d, Zn 4s, Zn 3d, In 5s, In 5p states.
关键词： chalcogenide,mid-infrared,second harmonic generation,laser damage threshold,nonlinear optical,supertetrahedron
更新于2025-09-04 15:30:14
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Structure-Selective Synthesis of Wurtzite and Zincblende ZnS, CdS, and CuInS <sub/>2</sub> Using Nanoparticle Cation Exchange Reactions
摘要： For polymorphic solid-state systems containing multiple distinct crystal structures of the same composition, identifying rational pathways to selectively target one particular structure is an important synthetic capability. Cation exchange reactions can transform a growing library of metal chalcogenide nanocrystals into different phases by replacing the cation sublattice, often while retaining morphology and crystal structure. However, only a few examples have been demonstrated where multiple distinct phases in a polymorphic system could be selectively accessed using nanocrystal cation exchange reactions. Here, we show that roxbyite (hexagonal) and digenite (cubic) Cu2?xS nanoparticles transform upon cation exchange with Cd2+, Zn2+, and In3+ to wurtzite (hexagonal) and zincblende (cubic) CdS, ZnS, and CuInS2, respectively. These products retain the anion and cation sublattice features programmed into the copper sulfide template, and each phase forms to the exclusion of other known crystal structures. These results significantly expand the scope of structure-selective cation exchange reactions in polymorphic systems.
关键词： zincblende,cation exchange reactions,wurtzite,ZnS,metal chalcogenide nanocrystals,CdS,polymorphic solid-state systems,CuInS2
更新于2025-09-04 15:30:14
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[SpringerBriefs in Materials] Anisotropic Metal Chalcogenide Nanomaterials (Synthesis, Assembly, and Applications) || Introduction
摘要： Nanoscience and nanotechnology have been putting the size and shape-dependent characteristics of matters on the horizon. Due to this reason, huge efforts have been poured into ?nding parameters affecting the intrinsic properties of materials at nanometer scale. Other than the size effect, shapes of nanomaterials produce a class of materials in which their properties are variable with direction. The anisotropy in chemical and physical features created vigorous attention in a way to synthesize 1D and 2D nanomaterials. Especially, metal chalcogenide (MC), constituting a series of compound materials with its vast library on the periodic table, has been studied and demonstrated to exploit in numerous applications.
关键词： metal chalcogenide,anisotropic nanomaterials,nanotechnology,nanoscience,1D and 2D nanomaterials
更新于2025-09-04 15:30:14
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Three-Dimensional Superlattices Based on Unusual Chalcogenide Supertetrahedral In–Sn–S Nanoclusters
摘要： Reported here are two novel metal chalcogenide superlattices built from unusual supertetrahedral TO2-InSnS clusters. With regard to only one previously reported case of a TO2-InS-based 2D-layered structure, such a combination of In?Sn?S components is leading to the first observation of 3D superlattices based on TO2-InSnS clusters. Besides, these title semiconducting materials also display good performance on the electrocatalytic oxygen reduction reaction.
关键词： 3D superlattices,metal chalcogenide,electrocatalytic oxygen reduction reaction,supertetrahedral clusters
更新于2025-09-04 15:30:14