- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Structural characteristics of m-plane AlN substrates and homoepitaxial films
摘要： Homoepitaxial non-polar AlN films were realized on m-plane (1010)-oriented AlN single crystals by metalorganic chemical vapor deposition (MOCVD). The microstructural properties of m-plane AlN substrates and homoepitaxial films were assessed by means of atomic force microscopy and high resolution x-ray diffraction characterization. Results indicated that both m-plane AlN substrates and films possessed exceptional structural quality, with some anisotropic mosaic distributions due to the quasi-bulk nature of the non-polar single crystals. An increase in the MOCVD growth temperature was noted to minimize the degree of inherited mosaic anisotropy without altering the m-plane AlN film growth rate, indicating that high temperature growth is critical to produce optimal film crystallinity. A dramatic change in the film surface morphology from heavily faceted “slate-like” features to monolayer steps was observed as the growth temperature was increased. The “slate-like” surface morphology produced low intensity cross-streaks in symmetric (1010) reciprocal space maps, tilted about 18° away from the (1010) crystal truncation rod. The orientation of these diffuse streaks corresponds to the physical alignment of the slates with respect to the substrate surface normal. X-ray line scans and defect-selective reciprocal space mapping confirmed that these low intensity streaks are solely dependent on this peculiar surface structure produced at low MOCVD growth temperatures and unrelated to basal plane stacking faults or other extended defects. All observations confirm that high quality III-nitride epitaxial structures on m-plane AlN substrates are attainable with controllable MOCVD growth processes, as demanded for future high performing AlN-based non-polar devices.
关键词： Characterization,Metalorganic chemical vapor deposition,High resolution x-ray diffraction,Surface structure,Nitrides,Crystal structure
更新于2025-09-04 15:30:14
-
Properties of Co‐Evaporated RbInSe <sub/>2</sub> Thin Films
摘要： The formation of an Rb-containing In-Se compound at the surface of Cu(In, Ga)Se2 (CIGS) thin films is assumed to be part of the mechanism of RbF post-deposition treatments (PDTs) performed on these absorber layers. Alkali-PDTs have acquired attention lately as they significantly enhance the efficiency of CIGS solar cells. In this contribution the formation of various phases during the RbF-PDT has been investigated. The results indicate that RbInSe2 is the most probable phase to form. Combining theoretical and experimental investigations, fundamental properties of a thermally co-evaporated RbInSe2 thin film are reported in order to serve as reference values in further studies.
关键词： CIGSe thin film solar cells,crystal structure,RbInSe2 deposition,defect calculation,electronic structure
更新于2025-09-04 15:30:14
-
Tuning the Crystalline Structure and Properties of TiO <i> <sub/>x</sub></i> Thin Films Deposited by DC Reactive Magnetron Sputtering by Adjusting the Ar/O <sub/>2</sub> Ratio
摘要： In this study, TiOx thin films were deposited by DC reactive magnetron sputtering (DC-RMS), using different Ar/O2 ratios in the absence of substrate bias and substrate heating. We observe a gradual change in the crystal structure and stoichiometry of the films with increasing Ar/O2 ratio, enabling to obtain TiOx films either with a pure anatase phase, a mixture between anatase and rutile, or a pure rutile phase. Our experimental results demonstrate that, by fine tuning the Ar/O2 ratio during DC-RMS deposition process, a TiOx thin film with tunable crystal structure and properties (surface morphology, atomic density, index of refraction, and film hardness) can be obtained in a simple way.
关键词： Sputtering,Physical Vapor Deposition,Thin Film,TiO2,Crystal Structure
更新于2025-09-04 15:30:14
-
Synthesis, Crystal Structure and Photophysical Properties of Two Reduced Schiff Bases Derived from 5-Aminoisophthalic Acid
摘要： Two reduced Schiff bases, namely 5-[(2-hydroxybenzyl)amino]isophthalic acid (1) and 5-[(pyridin-4-ylmethyl)amino] isophthalic acid (2), were synthesized in two-step method using 5-aminoisophthalic acid as the starting material, and were characterized by single-crystal X-ray diffraction, elemental analysis, infrared, 1H NMR, mass, absorption and fluorescence spectra. Both 1 and 2 crystallize in monoclinic system with space groups P21/c for 1 and P21/n for 2. Photophysical properties of both 1 and 2 are significantly different from those of raw material 5-aminoisophthalic acid due to stronger p → π conjugation when one amino hydrogen atom in 5-aminoisophthalic acid is substituted with electron-donor group. 1 displays a very strong narrow-band blue fluorescence with the maximum peak at 439 nm, a high quantum efficiency up to 64%, and a narrow full width at half maximum of 35 nm, while 2 has a broader and weaker fluorescence with the peak at 418 nm and FHWM of about 50 nm.
关键词： 5-[(2-Hydroxybenzyl)amino]isophthalic acid,5-Aminoisophthalic acid,Photophysical property,5-[(Pyridin-4-ylmethyl)amino]isophthalic acid,Crystal structure,Reduced Schiff base
更新于2025-09-04 15:30:14
-
Structure and luminescence of extraframework TiCl62? in Cs+-containing zeolite LTA
摘要： 2? ions were introduced into zeolite LTA at extraframework positions by allowing TiCl4(g) to react with Octahedral TiCl6 dehydrated Cs,Na-A. The structure of the product, Ti,Cl,Cs,Na-A, was determined by single-crystal crystallographic technique in the space group Pm?3m (a = 12.228(1) ?) and refined to the error index R1 = 0.046. Its composition was confirmed 2? ion is stabilized by by energy-dispersive X-ray analysis. Octahedral TiCl6 6+ cluster. Each of these Cl? ions bonds further to an 8-ring Cs+ ion. These eight surrounding Cs+ ions to form a Cs8TiCl6 9+ continuum in the surface volume 2? ions of adjacent unit cells to form a Cs11TiCl6 8-ring Cs+ ions bridge between TiCl6 of the crystal. The X-ray induced luminescence spectrum of the product is a broad band from 360 to 700 nm, peaking at 475 nm. The emission is red-shifted and less intense than those of M,Cl,Cs,Na-A, M = Zr and Hf, but appears to occur by the same self-trapped exciton (STE) mechanism. 2? ions center 8% of the large cavities. The TiCl6
关键词： Vapor-phase reaction,Luminescence,TiCl6 2?,Zeolite A,Crystal structure,Extraframework Ti4+
更新于2025-09-04 15:30:14
-
Molecular beam epitaxy growth of Mn4?Ni N thin films on MgO(0?0?1) substrates and their magnetic properties
摘要： We grew Mn4?xNixN epitaxial thin ?lms on MgO(0 0 1) by molecular beam epitaxy, as well as studied their crystalline qualities and magnetic properties. The ?lms were decomposed into Ni8N or Mn-Ni alloys when x ≥ 2, as con?rmed by X-ray di?raction and re?ection high-energy electron di?raction, but this decomposition was mitigated by reducing the substrate growth temperature. The lattice constants decreased with increased Ni substitution except when the Mn ratio was high, while the crystal orientation tended to degrade. The magnetic properties were measured via vibrating sample magnetometer, and it was found that the saturation magneti- zation (MS) and perpendicular magnetic anisotropy (PMA) diminished with a small amount of Ni substitution. Speci?cally, the MS value was remarkably decreased from 86.3 ± 1.1 emu/cm3 (Mn4N) to 19.0 ± 0.5 emu/cm3 (Mn3.85Ni0.25N), and the magnetic anisotropy constant was decreased from approximately 0.94–0.027 Merg/ cm3, respectively. The PMA vanished with further Ni substitution. Ultimately, a small MS and a PMA were simultaneously achieved with a small amount of Ni substitution. These properties support spin transfer torque, which can be applied to the emerging non-volatile memory devices using domain wall motion.
关键词： A3. Molecular beam epitaxy,A1. Crystal structure,B1. Mn4N,B2. Magnetic materials,B1. MgO,B1. Ni4N
更新于2025-09-04 15:30:14
-
Nickel(II) Coordination Complex Constructed from Benzimidazole and Pyridine-2,6-dicarboxylate Co-ligands: Synthesis, Crystal Structure, Thermal Behavior, and Photoluminescence
摘要： A Ni(II) complex, [Ni(pydca)(bim)3] (pydca = pyridine-2,6-dicarboxylate, bim = benzimidazole) has been prepared by hydrothermal synthesis. It is characterized by elemental analysis, IR and thermal analysis. The crystal structure is determined by single crystal X-ray diffraction. The mononuclear complexes are linked by N–H···O hydrogen bonds. The title complex has good thermal stability and exhibits good fluorescence properties in ethanol solution at room temperature.
关键词： crystal structure,Nickel(II) complex,6-dicarboxylate,hydrothermal synthesis,benzimidazole,photoluminescence,thermal behavior,pyridine-2
更新于2025-09-04 15:30:14
-
Synthesis, crystal structure, photoluminescence and photochemistry of bis(triphenylphosphine)silver(I) flavonolate
摘要： The complex Ag(I)(flavonolate)(PPh3)2 has been prepared and characterized including the crystal structure. This compound shows in degassed solution two emission bands, a fluorescence at λmax?=?505 nm and a phosphorescence at λmax?=?780 nm. Both emissions originate from lowest-energy flavonolate intraligand excited singlet and triplet states, respectively. In the presence of oxygen, the phosphorescence disappears and the complex becomes light-sensitive. The flavonolate ligand undergoes a photooxidation by oxygen.
关键词： crystal structure,silver(I),photochemistry,photoluminescence,flavonolate
更新于2025-09-04 15:30:14
-
MBE Growth and Optical Properties of Isotopically Purified ZnSe Heterostructures
摘要： Wide-gap II/VI heterostructures (HS) and quantum wells (QW) composed of ZnSe, CdSe, MgSe and their ternary and quaternary compounds are attractive candidates for modern quantum optical devices such as single photon sources and optically controlled spin qubits in the visible spectral range. In contrast to similar III/V semiconductor based devices, generally, most of the II/VI compounds allow for isotope purification towards zero nuclear spin species in the semiconductor environment. Using the same molecular beam epitaxy (MBE) system for natural and isotopically purified materials opposes the challenge to achieve superior isotope purity for example of Zn and Se species on the background of operation of the other effusion cells filled with natural isotopes. Here we report on the crystallographic and optical properties of ZnMgSe/ZnSe heterostructures and quantum wells grown by using 64Zn and 80Se isotopes and Mg with natural isotope distribution. We present a detailed quantitative secondary ion mass spectrometry (SIMS) analysis, which confirms that an extremely high grade of isotope purification of the ZnSe can be maintained although naturally and enriched Zn and Se elements are used in the same MBE system. This pioneering growth study forms a solid base to generate a spin vacuum ZnSe host crystal that is particularly suited for future studies on the dynamics of localized spins in II/VI heterostructures on a strongly extended coherence time scale.
关键词： Heterostructures,Molecular beam epitaxy,Optical properties,Crystal structure,X-ray diffraction,Isotope purification,Elementary analysis
更新于2025-09-04 15:30:14
-
A New Two-Dimensional Silver Coordination Polymer Constructed by 1,3-Bis(4-pyridyl)propane and 2,6-Dichlorophenylacetic Acid: Synthesis, Structure, Luminescence and Thermal Stable Properties
摘要： A novel complex 1 of {[Ag(bpp)(dcpa)] H2O}n [Hdcpa: 2,6-dichlorophenylacetic acid; bpp: 1,3-bis(4-pyridyl)propane] was synthesized and characterized by elemental analysis, IR, TGA, X-ray single crystal diffraction. The carboxylate oxygens of the Hdcpa ligands connect one Ag(I) ion in bidentate chelating mode to form mononuclear silver building blocks, which are into a 1D infinite chain through trans-bpp ligands. A two-dimensional network consist of adjacent Ag-bpp chain through Ag-Ag interaction. Furthermore, the luminescent property of complex 1 was investigated at room temperature. CCDC: 996495.
关键词： Crystal structure,Luminescence,Ag(I) coordinated polymer
更新于2025-09-04 15:30:14