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GaN grown by metalorganic vapor phase epitaxy
摘要： We report on residual impurities in semi-polar (3031) and (2021) GaN homo-epitaxial layer grown by metal-organic chemical vapor deposition. The (3031) and (2021) GaN layer showed atomically smooth surface and clear steps toward [0001] and [000-1], respectively. The residual impurity concentrations of oxygen and carbon were below the detection limit of secondary-ion mass spectroscopy. Low-temperature photoluminescence revealed that (2021) GaN layer consisted free excitons and Si donor bound excitons, along with two-electron satellite lines and longitudinal optical (LO) phonon coupling transitions. The results indicate semi-polar (3031) and (2021) GaN epitaxial layers are promising candidates in obtaining a high quality GaN drift layer for vertical GaN devices.
关键词： B2. Semiconducting III-V materials,A3. Metalorganic chemical vapor deposition,B1. Nitrides,A1. Crystal structure,A1. Impurities
更新于2025-09-19 17:15:36
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A series of two-dimensional lanthanide coordination polymers: synthesis, structures, magnetism and selective luminescence detection for heavy metal ions and toxic solvents
摘要： A series of two-dimensional lanthanide coordination polymers: synthesis, structures, magnetism and selective luminescence detection for heavy metal ions and toxic solvents
关键词： lanthanide ions,coordination polymers,luminescence properties,crystal structure,magnetic properties
更新于2025-09-19 17:15:36
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Composition, structure and morphology of ZnOa??Co3O4 ceramic targets in the process of pulsed laser thin film deposition
摘要： This paper presents the results of the study of the composition, structure and morphology of ZnO–Co3O4 ceramic targets before and after laser ablation by the KrF excimer laser. X-ray diffraction analysis showed that the composition of the targets changes under the thermal effects of laser radiation: a new phase of CoO of the cubic structure is formed (a = 4.25 ?). The radial distribution of elements in the ZnO–Co3O4 targets after ablation by the KrF excimer laser was discovered for the first time. The atomic concentration of cobalt in the center was determined to be several times higher than its concentration at the edge of the targets. This can be explained by the thermal model of laser-semiconductor interaction. The morphology of the targets surface after the laser ablation was discovered to undergo significant changes. Pulsed nanosecond laser radiation induces the formation of center-oriented cone-shaped structures and micro-whiskers on the target surface. It was determined that the higher is the concentration of doping impurities in the target, the greater is the number of structures observed on the surface. The formation of “cones” and microwhiskers is explained by the generalized growth model of the vapor–liquid–crystal mechanism.
关键词： A1. Growth models,A2. Bulk crystal growth,A1. Characterization,A3. Physical vapor deposition processes,B2. Semiconducting II-VI materials,A1. Crystal structure
更新于2025-09-19 17:13:59
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Oxygen controlled E-beam evaporation deposited p-SnOx thin film for photosensitive devices
摘要： Thin SnOx films of different thicknesses at different oxygen pressures were deposited on glass substrate using reactive E-beam evaporation technique. Significant changes in the optical and structural properties of the films with change in oxygen pressure are observed. Experimentally obtained absorption coefficient and band gap of SnOx suggests its prospective use as suitable absorber material for photoconductive and photovoltaic devices. In addition to the oxygen pressure, thickness of SnOx layer has also an important role on its optical and structural properties.
关键词： Semiconductor,Tin oxide,Optical property,Crystal structure,Thin film
更新于2025-09-19 17:13:59
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Na incorporation controlled single phase kesterite Cu2ZnSnS4 solar cell material
摘要： It is theoretically and experimentally challenging to fabricate single phase Cu2ZnSnS4 (CZTS) and more difficult to synthesize it by sol-gel method. Theoretical work reveals that Na can passivate the dangling bonds in the grain boundaries of CZTS and thus enhance the photovoltaic performance. Therefore, Na incorporation may be an effective way in passivating defects in CZTS films and fabricating CZTS with high quality and single phase. In this study, we will try to incorporate Na into CZTS films by sol-gel method to help passivate defects in CZTS and achieve single phase kesterite CZTS films using a different solvent 2-methoxybutanol. Different Na/(Cu+Zn+Sn) atomic ratios (0%-3%) will be employed. Through controlling Na incorporation amount in solution, we can prevent the generation of other phases like SnO2 and a pure single phase kesterite CZTS can be achieved. The optical band gap of the optimal CZTS film is 1.24 eV. All Na doped CZTS films show p-type conduction behavior.
关键词： Solar energy materials,Sol-gel preparation,Crystal structure
更新于2025-09-19 17:13:59
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Schiff Base Ancillary Ligands in Bis(diimine) Copper(I) Dye-Sensitized Solar Cells
摘要： Five 6,6’‐dimethyl‐2,2’‐bipyridine ligands bearing N‐arylmethaniminyl substituents in the 4‐ and 4’‐positions were prepared by Schiff base condensation in which the aryl group is Ph (1), 4‐tolyl (2), 4‐tBuC6H4 (3), 4‐MeOC6H4 (4), and 4‐Me2NC6H4 (5). The homoleptic copper(I) complexes [CuL2][PF6] (L = 1–5) were synthesized and characterized, and the single crystal structure of [Cu(1)2][PF6].Et2O was determined. By using the “surfaces‐as‐ligands, surfaces‐as‐complexes” (SALSAC) approach, the heteroleptic complexes [Cu(6)(Lancillary)]+ in which 6 is the anchoring ligand ((6,6’‐dimethyl‐[2,2’‐bipyridine]‐4,4’‐diyl)bis(4,1‐phenylene))bis(phosphonic acid)) and Lancillary = 1–5 were assembled on FTO‐TiO2 electrodes and incorporated as dyes into n‐type dye‐sensitized solar cells (DSCs). Data from triplicate, fully‐masked DSCs for each dye revealed that the best‐performing sensitizer is [Cu(6)(1)]+, which exhibits photoconversion efficiencies (η) of up to 1.51% compared to 5.74% for the standard reference dye N719. The introduction of the electron‐donating MeO and Me2N groups (Lancillary = 4 and 5) is detrimental, leading to a decrease in the short‐circuit current densities and external quantum efficiencies of the solar cells. In addition, a significant loss in open‐circuit voltage is observed for DSCs sensitized with [Cu(6)(5)]+, which contributes to low values of η for this dye. Comparisons between performances of DSCs containing [Cu(6)(1)]+ and [Cu(6)(4)]+ with those sensitized by analogous dyes lacking the imine bond indicate that the latter prevents efficient electron transfer across the dye.
关键词： Schiff base,phosphonic acid,crystal structure,dye‐sensitized solar cell,copper
更新于2025-09-19 17:13:59
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Structure and luminescent properties of new Dy3+/Eu3+/Sm3+-activated InNbTiO6 phosphors for white UV-LEDs
摘要： A series of novel Dy3+/Eu3+/Sm3+-activated InNbTiO6 phosphors have been prepared by conventional solid state reaction method. Based on the structure refinement, RE3+ ions are preferred to occupy the site of In3+ (2e) in the wolframite-type host lattice. According to their UV–visible diffusion reflectance spectra, the band gap and absorption property of un-doped InNbTiO6 sample can be tuned by the dopants. Under UV–visible light excitation, Dy3+ activators in this matrix mainly show emission lines originating from their characteristic f→f transitions. The optimal excitation and emission wavelength are 385 nm and 581 nm for Dy3+, 394 nm and 616 nm for Eu3+, and 406 nm and 615 nm for Sm3+, respectively. Concentration quenching occurs at 0.06 for Dy3+, 0.06 for Eu3+, and 0.04 for Sm3+, ascribed to resonant q-q, q-q, and d-q interactions, respectively. The luminescence lifetimes are determined to be 0.13, 0.50, and 0.50 ms for InNbTiO6:0.06Dy3+, InNbTiO6:0.06Eu3+, and InNbTiO6:0.04Sm3+, respectively. The Dy3+, Eu3+, and Sm3+ doped phosphors exhibited yellowish-white, red, and orange-red luminescence, respectively. The quantum yields and thermal stability of representative phosphors have been investigated. Present work shows that these new phosphors are promising for application in UV-LED solid-state lighting devices.
关键词： Band gap,Absorption property,Luminescence,Crystal structure
更新于2025-09-19 17:13:59
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Synthesis, Crystal Structure, and Optical Characterization of the Sulfide Chloride Oxide CsBa <sub/>6</sub> V <sub/>4</sub> S <sub/>12</sub> ClO <sub/>4</sub> with a Near-Infrared Fluorescence
摘要： When CsCl, BaS, BaO, V, and S are reacted in a solid-state reaction under inert conditions, pure powders and single crystals of senary CsBa6V4S12ClO4 can be obtained. Its unique crystal structure has the symmetry R3?H (no. 148) and unit cell parameters a = 9.0575(2) and c = 28.339(1) ?. The crystal structure contains polar units [VS3O]3? and a complex BaS7ClO2 coordination. The compound gets its deep-red color from a low-energy charge transfer, which can be explained by an electron transfer from S2? to V5+. In the near-infrared range, down-converted ?uorescence occurs at 1.06 and 0.90 eV, and both emissions appear <450 ps after excitation at about 1.27 eV.
关键词： optical characterization,crystal structure,near-infrared fluorescence,synthesis,sulfide chloride oxide
更新于2025-09-19 17:13:59
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Nearly Epitaxial Low-Resistive Co Germanide Formed by Atomic Layer Deposited Cobalt and Laser Thermal Annealing
摘要： With ALD-Co on n+-Ge (ND of 2×1019 cm-3) as the platform, annealing schemes including rapid thermal annealing (RTA) and laser thermal annealing (LTA) were employed to study its impact on the characteristics of CoGe2. CoGe2 formed by LTA shows no agglomeration and a low ρc of 1.3×10-8 Ω-cm2 which is reduced by 54 % as compared to the counterpart RTA. In addition, a uniform and atomically smooth CoGe2 with nearly epitaxial crystal structure is also achieved by LTA. Furthermore, LTA-formed CoGe2 does not require any barrier layer during formation which is in stark difference to other germanides and would greatly improve line resistance of the ever scaled contact trench. The promising results mainly stem from the low thermal budget with significant thermal gradient/shallow heat distribution of LTA that effectively limits excess surface Co diffusion and grooving effect, proving the high contact performance enabler beyond 5 nm node.
关键词： smooth interface,cobalt germanide,laser thermal annealing,contact resistivity,barrier,epitaxial crystal structure
更新于2025-09-16 10:30:52
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Unique Luminescence of Hexagonal Dominant Colloidal Copper Indium Sulphide Quantum Dots in Dispersed Solutions
摘要： Luminescent hexagonal dominant copper indium sulphide (h-dominant ciS) quantum dots (QDs) by precursor-injection of mixed metal-dialkyldithiocarbamate precursors. Owing to the different reactivity of the precursors, this method allowed the ciS QDs to grow while retaining the crystallinity of the hexagonal nucleus. The photoluminescence (PL) spectra exhibited dual emission (600–700 nm red emission and 700–800 nm NIR emission) resulting from the combined contributions of the hexagonal (wurtzite) h-ciS and tetragonal (chalcopyrite) t-ciS QDs, i.e. the niR and red emissions were due to the h-ciS QDs and coexisting t-ciS QDs (weight ratio of h-ciS/t-CIS ~ 10), respectively. The PL intensities of the h-ciS as well as t-ciS QDs were enhanced by post-synthetic heat treatment; the t-ciS QDs were particularly sensitive to the heat treatment. By separating h-ciS and t-ciS successfully, it was demonstrated that this phenomenon was not affected by size and composition but by the donor-acceptor pair states and defect concentration originating from their crystal structure. the h-dominant CIS QDs in this work provide a new technique to control the optical property of Cu-In-S ternary NCs.
关键词： defect states,copper indium sulphide,quantum dots,photoluminescence,crystal structure
更新于2025-09-16 10:30:52