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Extrinsic Defects in Crystalline MoO <sub/>3</sub> : Solubility and Effect on the Electronic Structure
摘要： The effect of six potential contaminants (Cu, In, Ga, Se, Sn and Zn) and five potential dopants (Ti, Mn, Sc, V and Y) on the electronic and optical properties of molybdenum oxide (MoO3) contact layers for solar cells was investigated using point defect analysis informed by density functional theory simulations. Of the contaminants investigated, Sn, In and Ga were found to be highly insoluble at all relevant temperatures and pressures, and therefore not a concern for solar cell manufacturing. Zn, Cu and Se exhibit some solubility, with the latter two appearing to introduce detrimental defect states near the valence band. This contamination can be avoided by increasing the O2 partial pressure during MoO3 deposition. Out of five potential aliovalent dopants, Sc, Ti and Y were disregarded due to their limited solubility in MoO3, while V was found to be highly soluble and Mn somewhat soluble. The effect of Mn and V doping was shown to be strongly dependent on the O2 partial pressure during deposition with a high pO2 favoring the formation of substitutional defects (potentially beneficial in the case of Mn doping due to the addition of defects states near the conduction band) while low pO2 favors interstitial defects.
关键词： electronic structure,solubility,solar cells,molybdenum oxide,extrinsic defects,point defect analysis,density functional theory,MoO3
更新于2025-09-23 15:21:21
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Hot electron thermoreflectance coefficient of gold during electron-phonon nonequilibrium
摘要： The temperature-dependent reflectivity of metals is quantified by the thermoreflectance coefficient, which is a material dependent parameter that depends on the metallic band structure, electron scattering dynamics, and photon wavelength. After short-pulse laser heating, the electronic sub-system in a metal can be driven to temperatures much higher than that of the lattice, which gives rise to unique non-equilibrium electron and phonon scattering dynamics, leading to a “hot electron” thermoreflectance that is different from the traditionally measured equilibrium coefficient. In this work, we analytically quantify and experimentally measure this hot electron thermoreflectance coefficient through ultrafast pump-probe measurements of thin gold films on silica glass and sapphire substrates. We demonstrate the ability to not only quantify the thermoreflectance during electron-phonon nonequilibrium, but also validate this coefficient’s predicted dependence on the absolute temperature of the electronic subsystem. The approach outlined in this work provides a metrology to further understand and quantify excited-state scattering effects on the dielectric function of metals.
关键词： electron-phonon scattering,Pump-probe,Thermoreflectance,Drude model,electronic temperature
更新于2025-09-23 15:21:21
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Photofragment Translational Spectroscopy Studies of H Atom Loss Following Ultraviolet Photoexcitation of Methimazole in the Gas Phase
摘要： The ultraviolet (UV) photodissociation of gas phase methimazole has been investigated by H Rydberg atom photofragment translational spectroscopy methods at many wavelengths in the range 222.5 – 275 nm and by complementary electronic structure calculations. Methimazole is shown to exist predominantly as the thione tautomer, 1-methyl-2(3H)-imidazolinethione, rather than the commonly given thiol form, 2-mercapto-1-methylimidazole. The UV absorption spectrum of methimazole is dominated by the S4←S0 transition of the thione tautomer, which involves electron promotion from an a′ (py) orbital localized on the sulfur atom to a σ* orbital localized around the N–H bond. Two H atom formation pathways are identified following UV photoexcitation. One, involving prompt, excited state N–H bond fission, yields vibrationally cold but rotationally excited methimazolyl (Myl) radicals in their first excited (??) electronic state. The second yields H atoms with an isotropic recoil velocity distribution peaking at low kinetic energies but extending to the energetic limit allowed by energy conservation given a ground state dissociation energy D0(Myl–H) ~24 000 cm-1. These latter H atoms are attributed to the unimolecular decay of highly vibrationally excited S0 parent molecules. The companion electronic structure calculations provide rationales for both fragmentation pathways and the accompanying product energy disposals, and highlight similarities and differences between the UV photochemistry of methimazole and that of other azoles (e.g. imidazole) and with molecules like thiourea and thiouracil that contain similar N–C=S motifs.
关键词： methimazolyl radicals,unimolecular decay,H Rydberg atom photofragment translational spectroscopy,ultraviolet photodissociation,N–H bond fission,methimazole,electronic structure calculations,thione tautomer
更新于2025-09-23 15:21:21
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Structural determination of phosphosilicate glass based on first-principles molecular dynamics calculation
摘要： We report static and dynamic first-principles calculations determining the structure and electronic properties of phosphosilicate glass (PSG). A stable structure of PSG with composition of (SiO2)x(P2O5)y was calculated by simulated annealing based on Car–Parrinello molecular dynamics (CPMD) with a real-space density functional theory (RSDFT) code. As a result, phosphorus (P) atoms in PSG were four-fold coordinated with oxygen (O) atoms and one of the four PO bonds was dangling toward the interstitial region (an –O3PO configuration). We also compared the structures having a different number of O atoms to discuss the stable configuration of PSG in the realistic situation of phosphoryl chloride (POCl3) annealing. We found that –O3PO is most stable for O2-rich conditions, whereas three-coordinate P (an –O3P configuration) becomes stable in O2-poor conditions. The candidates of the states which create levels inside the bandgap of PSG were also calculated.
关键词： phosphosilicate glass,molecular dynamics,first-principles calculation,electronic properties,POCl3 annealing
更新于2025-09-23 15:21:21
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The Longest Acene Diimide To Date
摘要： Acenes are promising high-conductive materials that possess small band gaps that can quickly decrease with longer conjugated π-systems. However, large acenes are susceptible to poor solubility and high reactivity with the extension of the π-system. Introduction of electron-withdrawing imide groups to the acenes have gained attention because they can induce good solubility and high stability. Here, Li, Wang and co-workers report the synthesis of unprecedented hexacene diimides and show their ambipolar transport behavior.
关键词： zirconocenes,acenes,electronic materials,imides
更新于2025-09-23 15:21:21
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[Advances in Intelligent Systems and Computing] Emerging Trends in Expert Applications and Security Volume 841 (Proceedings of ICETEAS 2018) || Bone Fracture Detection from X-Ray Image of Human Fingers Using Image Processing
摘要： Orthopaedics deals with surgery and treatment of the human musculoskeletal system. It also involves degenerative conditions, trauma, sports injury, tumors, and congenital issues. Orthopaedic doctors are always interested to take an X-Ray image of injured parts of patient’s body for better diagnosis. In an X-Ray imaging, electronic radiation is passed in the human body for capturing bone images. After X-Ray image retrieval, a doctor examines X-Ray image manually. It is not that easy to detect most of the major diseases/issues related with the bones just by visualizing an X-Ray image, although in some cases, it is possible, but till that time, diseases may reached towards next or serious stage for example bone fracture. The main problem with X-Ray images is that they may be blurred, out of focus, improperly bright and noisy, which makes examination more dif?cult. One of the solutions to all above problems can be computerized image processing of human being’s X-Ray images. In this research paper, we have presented an algorithm to detect bone fracture from X-Ray images of human ?ngers using image processing.
关键词： Trauma,Orthopaedics,Image processing,Musculoskeletal,X-Ray,Electronic radiation
更新于2025-09-23 15:21:21
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Electronic transport in degenerate (100) scandium nitride thin films on magnesium oxide substrates
摘要： Scandium nitride (ScN) is a degenerate n-type semiconductor with very high carrier concentrations, low resistivity, and carrier mobilities comparable to those of transparent conducting oxides such as zinc oxide. Because of its small lattice mismatch to gallium nitride (GaN), <1%, ScN is considered a very promising material for future GaN based electronics. Impurities are the source of the degeneracy. Yet, which specific impurities are the cause has remained in contention. ScN thin films of various thicknesses were grown on magnesium oxide substrates in a (001) orientation using reactive magnetron sputtering across a range of deposition conditions. X-ray diffraction was used to verify crystal orientation. Film thicknesses ranging from 39 to 85 nm were measured using scanning electron microscopy. The electronic transport properties of the films were characterized using Hall-effect measurements at temperatures ranging from 10 to 320 K. At 10 K, the electron concentration varies from 4.4 (cid:2) 1020 to 1.5 (cid:2) 1021 cm(cid:3)3, resistivity from 2.1 (cid:2) 10(cid:3)4 to 5.0 (cid:2) 10(cid:3)5 X(cid:4)cm, and Hall mobility from 66 to 97 cm2/V(cid:4)s. Secondary ion mass spectroscopy (SIMS) was used to determine film compositions. Finally, density functional theory (DFT) was used to compute the activation energies for various point defects including nitrogen and scandium vacancies and oxygen and fluorine substituting for nitrogen. For both oxygen and fluorine substitution, the energies were negative, indicating spontaneous formation. Nevertheless, the combined results of the Hall, SIMS, and DFT strongly suggest that oxygen substitution is the primary mechanism behind the high carrier concentration in these samples.
关键词： degenerate n-type semiconductor,Hall-effect measurements,Scandium nitride,density functional theory,electronic transport properties
更新于2025-09-23 15:21:21
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Compact antipodal Vivaldi antenna with rectangular slots and shaping of flare to cover 6 to 18 GHz
摘要： The compact antipodal Vivaldi antenna (AVA) with regular rectangular slots in the taper region is presented in this paper intended for electronic warfare applications. The antenna has a simple configuration with compact size. Micro strip line feeding is employed. The rectangular slots at regular intervals and terminal elliptical shaping of taper on top and bottom layers of antenna substrate enhance impedance bandwidth. The slot loading in the taper portion also enhances the gain. The novel feature of this antenna is its small aperture size which is 25 mm. Small aperture size is required for array applications to avoid grating lobes and element pattern nulls. A return loss of less than ?10 dB (VSWR <2.0) is obtained over 6 to 18 GHz. The antenna is designed using Ansoft HFSS software and the same is implemented in hardware. Return loss, radiation patterns, and gain have been measured and results reported.
关键词： Electronic Warfare,Printed antennas,Array elements
更新于2025-09-23 15:21:21
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Investigation of the structural and electronic properties of InP1-xSbx alloy for mid-infrared optoelectronic applications: A TB-mBJ DFT study
摘要： The structural and electronic properties of InP1(cid:1)xSbx supercell structure at different percent of Sb incorporation have been studied under the Density Functional Theory formalism employing WIEN2K package. From the total energy calculations, the supercell lattice structures have been optimized. The structural properties have been calculated from the equation of state which suggests the supercell structures to be signi?cantly stable with a higher degree of compressive ?exibility (speci?cally, at lower percent of Sb incorporation). The contribution of the partial and total DOS (Density of States) of constituent elements to total DOS of the supercell structure has been investigated. The relativistic effects have been assimilated into the band structure calculation, along various high symmetry k directions for each supercell structure. The values obtained for band gap (both, direct and indirect), spin-orbit splitting energy and bowing coef?cient have been observed to vary signi?cantly as a function of Sb mole fraction. Moreover, a relationship has been established between band gap (both, direct and indirect) values and spin-orbit splitting energy with Sb mole fraction. The in?uence of SOC (spin-orbit coupling) effect on the parameters concerning electronic properties has also been analyzed. The effective mass values for conduction and valence sub-bands (heavy hole, light hole and spin orbit split-off hole) near the Brillouin zone has been calculated at different percent of Sb incorporation in InP1(cid:1)xSbx supercell structure. The interpretation of these results obtained suggests InP1(cid:1)xSbx material to be competent for mid-infrared optoelectronic applications.
关键词： III-V semiconductor,Electronic band structure,DOS,DFT calculation,Effective mass calculation,Structural and electronic property
更新于2025-09-23 15:21:01
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Analysis of the A ??=1 a?? X 3?￡a??0+ transition of PtS observed by intracavity laser spectroscopy with fourier transform detection (ILS-FTS), and computational studies of electronic states of PtS
摘要： The (0,0) and (1,0) vibrational bands of the A U?1 e X 3S?0t transition of PtS have been observed in high resolution absorption measurements recorded using intracavity laser spectroscopy with Fourier transform detection (ILS-FTS). Hyper?ne structure in 195PtS lines was observed in the Q-branches only, due to the interaction of an unknown U?0? state with the f levels of the A U?1 state. The new (0,0) vibrational band has been rotationally analyzed and ?t using PGOPHER. Results from the spectral analysis including deperturbation of the (0,0) band of the A U?1 state are presented. Potential energy curves, spectroscopic constants, and transition dipole moments are presented for L-S and U electronic states with Te < 25,000 cm?1, based on high-level ab initio calculations. Experimentally observed electronic states of PtS are correlated to predicted states.
关键词： Platinum sul?de,PtS,High-resolution electronic spectra of metal-containing radicals,Ro-electronic analysis,ILS-FTS,Perturbation analysis
更新于2025-09-23 15:21:01