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Synergistic effect of surface oxygen vacancies and interfacial charge transfer on Fe(III)/Bi2MoO6 for efficient photocatalysis
摘要： Novel Fe(III) clusters grafted Bi2MoO6 nanosheets with surface oxygen vacancies (denoted as F/BMO-SOVs) heterostructured composite have been firstly fabricated via a reliable calcination process combined with impregnation approach. The surface oxygen vacancies (SOVs) in Bi2MoO6 were formed due to controlled calcination process. The presence of Fe (III) clusters was confirmed by HRTEM, XPS, and UV-Vis DRS. Under visible light irradiation, the optimum molar ratio of 15% F/BMO-SOVs achieved 93.4% degradation efficiency of phenol within 180 min, representing nearly 80 times higher activity than the pure Bi2MoO6, confirmed by both absorption spectrum and TOC measurement. The dramatically enhanced photocatalytic activity is attributed to the synergistic effect between the SOVs, Fe(III) clusters and Bi2MoO6, which not only narrows the band gap, improving the visible light response ability, but also facilitates the direct interfacial charge transfer (IFCT) from the SOVs to the surface Fe(III) clusters, greatly promoting the efficient separation of photogenerated electron-hole pairs. According to the trapping experiments and ESR measurements results, ·O2-, ·OH-, and h+ all participated in the phenol photodegradation process over F/BMO-SOVs. Thus, this work not only provides a synergistic effect between SOVs, Fe(III) clusters and Bi2MoO6 involving an IFCT process, but also proposes an efficient approach to fabricating highly active photocatalysts in environmental remediation and solar fuel synthesis.
关键词： Surface oxygen vacancy,Phenol degradation,Synergistic effect,Interfacial charge transfer,Heterostructured Fe(III)/Bi2MoO6
更新于2025-09-19 17:15:36
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Gate Bias and Length Dependences of Total-Ionizing-Dose Effects in InGaAs FinFETs on Bulk Si
摘要： We evaluate the total-ionizing-dose (TID) responses of InGaAs nMOS FinFETs with different gate lengths irradiated with 10-keV X-rays under different gate biases. The largest degradation after irradiation occurs at VG = -1 V. Radiation-induced trapped positive charge dominates the TID response of InGaAs FinFET transistors, consistent with previous results for InGaAs multi-fin capacitors. Shorter gate-length devices show larger radiation-induced charge trapping than longer gate-length devices, most likely due to the electrostatic effects of trapped charge in the surrounding SiO2 isolation and SiO2/Si3N4 spacer oxides. 1/f noise measurements indicate a high trap density and a non-uniform defect-energy distribution, consistent with a strong variation of effective border-trap density with surface potential.
关键词： 1/f noise,FinFETs,InGaAs,Total-Ionizing-Dose,Bulk Si,border-trap,Gate length dependence,III-V
更新于2025-09-19 17:15:36
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Synthesis and Fluorescence Properties of a Structurally Characterized Hetero-Hexanuclear Zn(II)-La(III) Salamo-Like Coordination Compound Containing Auxiliary Ligands
摘要： A hetero-hexanuclear Zn(II)-La(III) coordination compound, [{(ZnL)2La}2(bdc)2](NO3)2 (H2bdc = terephthalic acid) has been synthesized with a symmetric Salamo-like bisoxime, and characterized by elemental analyses, IR, UV-Vis, fluorescent spectroscopy, and single-crystal X-ray diffraction analysis. All of the Zn(II) ions are pentacoordinated by N2O2 donator atoms from the (L)2? unit and one oxygen atom from one terephthalate anion. The Zn(II) ions adopt trigonal bipyramidal geometries (τZn1 = 0.61, τZn2 = 0.56). The La(III) ions are decacoordinated in the Zn(II)-La(III) coordination compound and has a distorted bicapped square antiprism geometry. Meanwhile, the photophysical property of the Zn(II)-La(III) coordination compound was also measured and discussed.
关键词： crystal structure,photophysical property,Salamo-like bisoxime,Zn(II)-La(III) coordination compound
更新于2025-09-19 17:15:36
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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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Synthesis and structural characterization of microcrystalline Ga2S3 layers on a GaP semiconductor substrate
摘要： Gallium sulfide (Ga2S3) belongs to a group of wide bandgap semiconductors with interesting properties for infrared and nonlinear optics applications. Recent interest in Ga2S3 material focuses on the passivation of various semiconductor surfaces to enhance their electrical and optical properties. This work concerns the growth of microcrystalline gallium sulfide layers on semiconductive GaP substrates. The Ga2S3 layers were successfully obtained by reacting sulfur vapour with thin GaP semiconductor plates at two different temperatures: 450 °C and 600 °C. At the lower temperature (400 °C), no gallium sulfide layer formation was observed on the GaP substrate. Atomic force microscopy and Scanning Electron Microscopy were applied to illustrate the topography of the obtained Ga2S3 layers. Their thickness ranged from a few hundred nanometers to about 1–2 μm. The synthesized layers were structurally characterized by Raman spectroscopy. Raman polarization measurements were used to determine the crystalline phase of the Ga2S3 films. Raman tensor coefficients were obtained by fitting the most intensive Ga2S3 peaks to experimental data. The symmetry of the Raman peaks was in good agreement with the monoclinic Ga2S3 crystal phase.
关键词： Ga2S3 layers,Raman polarization measurements,Gallium (III) sulfide,Wide bandgap semiconductors
更新于2025-09-19 17:15:36
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Highly tin doped GaAs at low growth temperatures using tetraethyl tin by metal organic vapor phase epitaxy
摘要： GaAs layers with a high tin (Sn) doping concentration and a smooth surface morphology were successfully grown at temperatures as low as 425 °C using tetraethyl tin (TESn) by metal organic vapor phase epitaxy (MOVPE). The samples grown at 650 °C showed Sn-rich droplets even with a low TESn molar flow rate of 0.06 μmol/min, indicating that Sn atoms were not incorporated into the GaAs film but segregated and accumulated on the film surface. Droplet formation was suppressed at a low growth temperature of 425 °C. This suggests that the segregation process is kinetically-limited, with the segregation mechanism is slow compared to the growth rate at low growth temperatures. Uncorrected Hall effect measurements found an electron concentration of ～1 × 1019 cm?3, which is close to the maximum reported doping-limit obtainable in GaAs:Sn grown by MOVPE, while avoiding droplet formation and maintaining a smooth surface morphology. The electron mobility is dominated by the ionized impurity scattering. The sample possesses a generally flat Sn profile extending from the substrate to the film surface. Secondary ion mass spectroscopy indicates that the Sn is electrically active but compensated by carbon acceptors to yield the measured carrier concentration.
关键词： A1. Segregation,B2. Semiconducting III-V materials,A1. Doping,A3. Metalorganic vapor phase epitaxy
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 2nd International Conference on Power and Energy Applications (ICPEA) - Singapore, Singapore (2019.4.27-2019.4.30)] 2019 IEEE 2nd International Conference on Power and Energy Applications (ICPEA) - Characteristics of Disturbance in Frequency 9 -150 kHz of Photovoltaic System under Fluctuated Solar Irradiance
摘要： Gallium nitride (GaN) is a wide bandgap semiconductor material and is the most popular material after silicon in the semiconductor industry. The prime movers behind this trend are LEDs, microwave, and more recently, power electronics. New areas of research also include spintronics and nanoribbon transistors, which leverage some of the unique properties of GaN. GaN has electron mobility comparable with silicon, but with a bandgap that is three times larger, making it an excellent candidate for high-power applications and high-temperature operation. The ability to form thin-AlGaN/GaN heterostructures, which exhibit the 2-D electron gas phenomenon leads to high-electron mobility transistors, which exhibit high Johnson’s figure of merit. Another interesting direction for GaN research, which is largely unexplored, is GaN-based micromechanical devices or GaN microelectromechanical systems (MEMS). To fully unlock the potential of GaN and realize new advanced all-GaN integrated circuits, it is essential to cointegrate passive devices (such as resonators and filters), sensors (such as temperature and gas sensors), and other more than Moore functional devices with GaN active electronics. Therefore, there is a growing interest in the use of GaN as a mechanical material. This paper reviews the electromechanical, thermal, acoustic, and piezoelectric properties of GaN, and describes the working principle of some of the reported high-performance GaN-based microelectromechanical components. It also provides an outlook for possible research directions in GaN MEMS.
关键词： HEMT,piezoelectric materials,micromachining,microelectromechanical systems,III-V,wide bandgap,resonators
更新于2025-09-19 17:13:59
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Thermal Design Considerations for III-N Vertical-Cavity Surface-Emitting Lasers Using Electro-Opto-Thermal Numerical Simulations
摘要： III-N VCSELs undergo severe self-heating which limits the output optical power. This makes thermal management a critical design consideration. The three most common VCSEL structures (hybrid VCSELs, flip-chip VCSELs and ELOG VCSELs) have been studied using advanced self-consistent electro-opto-thermal numerical simulations. The key geometric and material parameters affecting the thermal resistance of these devices have been identified. Our simulations suggest that some of the proposed solutions and design modifications can increase the maximum optical output power by as much 100%. This manuscript also describes the correct method of using numerical simulation in device design—to predict trends and isolate the key factors affecting device performance.
关键词： electro-opto-thermal simulation,thermal resistance,VCSEL,III-Nitride,laser diode,device modeling
更新于2025-09-19 17:13:59
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Bis-Cyclometalated Iridium Complexes Containing 4,4a?2-Bis(phosphonomethyl)-2,2a?2-bipyridine Ligands: Photophysics, Electrochemistry, and High-Voltage Dye-Sensitized Solar Cells
摘要： In this report, the synthesis and characterization of two bis-cyclometalated iridium(III) complexes are presented. Single-crystal X-ray diffraction shows [Ir(ppy)2(4,4′-bis(diethylphosphonomethyl)-2,2′-bipyridine)]PF6 adopts a pseudo-octahedral geometry. The complexes have an absorption feature in the near-visible?UV region and emit green light with excited-state lifetimes in hundreds of nanoseconds. The redox properties of these complexes show reversible behavior for both oxidative and reductive events. [Ir(ppy)2(4,4′-bis(phosphonomethyl)-2,2′-bipyridine)]PF6 readily binds to metal oxide supports, like nanostructured SnIV-doped In2O3 and TiO2, while still retaining reversible redox chemistry. When incorporated as the photoanode in dye-sensitized solar cells, the devices exhibit open-circuit voltages of >1 V, which is a testament to their strength of these iridium(III) complexes as photochemical oxidants.
关键词： high-voltage,dye-sensitized solar cells,bis-cyclometalated iridium(III) complexes,electrochemistry,photophysics
更新于2025-09-19 17:13:59
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Neutral Cyclometalated Iridium(III) Complexes Bearing Substituted N-Heterocyclic Carbene (NHC) Ligands for High-Performance Yellow OLED Application
摘要： The synthesis, crystal structure, and photophysics of a series of neutral cyclometalated iridium(III) complexes bearing substituted N-heterocyclic carbene (NHC) ancillary ligands ((C∧N)2Ir(R-NHC), where C∧N and NHC refer to the cyclometalating ligand benzo[h]quinoline and 1-phenylbenzimidazole, respectively) are reported. The NHC ligands were substituted with electron-withdrawing or -donating groups on C4′ of the phenyl ring (R = NO2 (Ir1), CN (Ir2), H (Ir3), OCH3 (Ir4), N(CH3)2 (Ir5)) or C5 of the benzimidazole ring (R = NO2 (Ir6), N(CH3)2 (Ir7)). The configuration of Ir1 was confirmed by a single-crystal X-ray diffraction analysis. The ground- and excited-state properties of Ir1?Ir7 were investigated by both spectroscopic methods and time-dependent density functional theory (TDDFT) calculations. All complexes possessed moderately strong structureless absorption bands at ca. 440 nm that originated from the C∧N ligand based 1π,π*/1CT (charge transfer)/1d,d transitions and very weak spin?forbidden 3MLCT (metal-to-ligand charge transfer)/3LLCT (ligand-to-ligand charge transfer) transitions beyond 500 nm. Electron-withdrawing substituents caused a slight blue shift of the 1π,π*/1CT/1d,d band, while electron-donating substituents induced a red shift of this band in comparison to the unsubstituted complex Ir3. Except for the weakly emissive nitro-substituted complexes Ir1 and Ir6 that had much shorter lifetimes (≤160 ns), the other complexes are highly emissive in organic solutions with microsecond lifetimes at ca. 540?550 nm at room temperature, with the emitting states being predominantly assigned to 3π,π*/3MLCT states. Although the effect of the substituents on the emission energy was insignificant, the effects on the emission quantum yields and lifetimes were drastic. All complexes also exhibited broad triplet excited-state absorption at 460?700 nm with similar spectral features, indicating the similar parentage of the lowest triplet excited states. The highly emissive Ir2 was used as a dopant for organic light-emitting diode (OLED) fabrication. The device displayed a yellow emission with a maximum current efficiency (ηc) of 71.29 cd A?1, a maximum luminance (Lmax) of 32747 cd m?2, and a maximum external quantum efficiency (EQE) of 20.6%. These results suggest the potential of utilizing this type of neutral Ir(III) complex as an efficient yellow phosphorescent emitter.
关键词： cyclometalated iridium(III) complexes,phosphorescent emitter,OLED,photophysics,N-heterocyclic carbene (NHC) ligands
更新于2025-09-19 17:13:59