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[IEEE 2019 IEEE Pulsed Power & Plasma Science (PPPS) - Orlando, FL, USA (2019.6.23-2019.6.29)] 2019 IEEE Pulsed Power & Plasma Science (PPPS) - Auto-collimation and monitoring of laser beam in high power electron-pumped KrF laser facility
摘要： Record low values in this material system of threshold current density, particularly at elevated temperature, are presented for InP quantum dot lasers. Lasers with Ga0 .5 8 In0 .4 2 P in the dot upper con?ning layer have the lowest threshold current densities, 138 A·cm?2 at 300 K, and 235 A·cm?2 at 350 K (77 °C) (2-mm lasers, uncoated facets). Gain-current density data suggests laser performance with an upper con?ning layer of Gax In1 ?xP with x = 0.54, 0.56 or 0.58 would be similar if not for the very low internal optical mode loss, αi of samples with x = 0.56 and 0.58. Gain measurements at ?xed inversion level suggest that increasing x content in Gax In1 ?xP increases gain at ?xed inversion level but samples with x = 0.54 also exhibit reduced recombination current density. The increasing recombination current density at elevated temperature due to thermal carrier spreading is signi?cantly reduced in samples with x = 0.56 and x = 0.58 but measurements at common operating points attribute this largely to the reduced αi for these samples and given the same αI , samples with x = 0.54, 0.56 and 0.58 would all bene?t from reduced effects due to thermal carrier spreading compared to x = 0.52.
关键词： Quantum dot devices,InP self-assembled quantum dots,semiconductor laser,short wavelength lasers,threshold current density,temperature sensitivity
更新于2025-09-19 17:13:59
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Development of dual quantum dots-based fluorescence-linked immunosorbent assay for simultaneous detection on inflammation biomarkers
摘要： Simultaneous detections of di?erent but clinically relevant biomarkers are of extremely importance in biomedicine. Due to their unique photophysical properties, quantum dots (QDs) are ideally suited for highly sensitive multiplexed determination. Herein, a dual quantum dots-based ?uorescence-linked immunosorbent assay (dQDs-FLISA) for simultaneous and quantitative detection of in?ammation biomarkers (i.e. serum amyloid A (SAA) and C-reactive protein (CRP)) has been established. After being coated by amphiphilic oligomers (poly-maleic acid n-hexadecanol ester, PMAH), the red-QD and green-QD with high quantum yields were used as ?uorescence probes to couple SAA and CRP antibodies, respectively. Cross-reactivity among the SAA and CRP’s antibodies and antigens have been carefully examined by interference experiments, and it was successfully avoided by the speci?c probe adding sequence. Therefore, the assay provided a broad linear analytical range, including SAA quantitative range of 10–1,000 ng mL?1 with linear correlation (R2) of 0.992, and CRP quantitative range of 10–1,000 ng mL?1 with R2 of 0.998. The limit of detections (LODs) for SAA and CRP using dQDs-FLISA were 2.39 ng mL?1 and 6.37 ng mL?1, respectively. The accuracy of the assay has been con?rmed with recoveries of 92.13%–101.85%. More importantly, the assay results showed good speci?city, the QD-antibody probe could couple corresponding antigen (CRP or SAA) high-e?ciently and it could be out of interference of other antigens and substances in serum. Given its good performance, the proposed dQDs-FLISA method o?ers great potential for simultaneous and quantitative detection of other biomarkers in in vitro diagnostic (IVD).
关键词： Quantum dot-based ?uorescence-linked immunosorbent assay,In?ammation biomarkers,Simultaneous detection,Quantum dots
更新于2025-09-19 17:13:59
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Temperature-Independent Performance of an 8-Layer ?? ~1.3 ??m InAs/GaAs Quantum-Dot Laser
摘要： We report high-performance broad-area eight-layer InAs/GaAs quantum-dot lasers (QDLs) emitting at 1.3 μm in the pulse and continuous-wave (CW) operations. Operational characteristics of the fabricated QDLs, including the emission wavelength, output power, threshold-current density, di?erential quantum e?ciency, and characteristic temperature, are investigated at di?erent temperatures. For as-cleaved facets of 100 μm wide and 1 mm cavity-length device, an output power of 100 mW is achieved at 1 kHz with 5% duty cycle and 49 mW in the CW operation. The device exhibits a threshold-current density of 56 A/cm2 at room temperature in both the operating modes and increases to 71 and 80 A/cm2 the in the pulse and CW modes, respectively, at 343 K. Over a temperature range of 298 K to 343 K, we calculate the threshold characteristic temperature of 166 K and 119 K and slope-e?ciency characteristic temperature of 2061 K and 408 K in the pulse and CW modes, respectively. The laser exhibits di?erential quantum e?ciency of 41% and 32% in the pulse and CW mode, respectively. We observed that the device exhibited negligible dependence over a temperature range of 298 K to 343 K.
关键词： characteristic temperature,quantum-dot laser,di?erential quantum e?ciency,semiconductor laser
更新于2025-09-19 17:13:59
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Coherent spin control of s-, p-, d- and f-electrons in a silicon quantum dot
摘要： Once the periodic properties of elements were unveiled, chemical behaviour could be understood in terms of the valence of atoms. Ideally, this rationale would extend to quantum dots, and quantum computation could be performed by merely controlling the outer-shell electrons of dot-based qubits. Imperfections in semiconductor materials disrupt this analogy, so real devices seldom display a systematic many-electron arrangement. We demonstrate here an electrostatically confined quantum dot that reveals a well defined shell structure. We observe four shells (31 electrons) with multiplicities given by spin and valley degrees of freedom. Various fillings containing a single valence electron—namely 1, 5, 13 and 25 electrons—are found to be potential qubits. An integrated micromagnet allows us to perform electrically-driven spin resonance (EDSR), leading to faster Rabi rotations and higher fidelity single qubit gates at higher shell states. We investigate the impact of orbital excitations on single qubits as a function of the dot deformation and exploit it for faster qubit control.
关键词： Rabi oscillations,silicon quantum dot,spin qubits,electrically-driven spin resonance,quantum dots
更新于2025-09-19 17:13:59
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[IEEE 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Guangzhou, China (2019.5.19-2019.5.22)] 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - A Circularly Polarized Waveguide Slot Antenna for Random Array Application
摘要： Record low values in this material system of threshold current density, particularly at elevated temperature, are presented for InP quantum dot lasers. Lasers with Ga0.58In0.42P in the dot upper con?ning layer have the lowest threshold current densities, 138 A·cm?2 at 300 K, and 235 A·cm?2 at 350 K (77 °C) (2-mm lasers, uncoated facets). Gain-current density data suggests laser performance with an upper con?ning layer of GaxIn1?xP with x = 0.54, 0.56 or 0.58 would be similar if not for the very low internal optical mode loss, αi of samples with x = 0.56 and 0.58. Gain measurements at ?xed inversion level suggest that increasing x content in GaxIn1?xP increases gain at ?xed inversion level but samples with x = 0.54 also exhibit reduced recombination current density. The increasing recombination current density at elevated temperature due to thermal carrier spreading is signi?cantly reduced in samples with x = 0.56 and x = 0.58 but measurements at common operating points attribute this largely to the reduced αi for these samples and given the same αI, samples with x = 0.54, 0.56 and 0.58 would all bene?t from reduced effects due to thermal carrier spreading compared to x = 0.52.
关键词： Quantum dot devices,InP self-assembled quantum dots,semiconductor laser,short wavelength lasers,threshold current density,temperature sensitivity
更新于2025-09-19 17:13:59
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Efficiency improvement of GaAs Quantum Dot in GaAs1-xPx matrix for solar cell applications
摘要： In this paper, we present simulations and the optimization of electrical and optical properties of GaAs Quantum Dots (QD) in a GaAs1-xPx matrix. Our results showed that 25 GaAs/GaAs1-xPx QD layers provide a relative enhancement of 41.34 % and 75.40 % of the short-circuit current and efficiency, respectively. With the same number of the QD layers, the External Quantum Efficiency (EQE) measurement shows that the absorption range edge of low energy photons has been extended from 875 to 1200 nm (?EQE= 25%). The temperature effect has been studied for a different number of QD inserted. The optimal conversion efficiency of 25 QD layers is degraded from 23.50% to 18.70 % by increasing the temperature from 273 K to 350 K. Moreover, the electrical features obtained and EQE measurements for GaAs/GaAs1-xPx QDSC have been compared with those obtained for In0.47Ga0.53As/GaAs0.86P0.14 QDSC, In0.167Ga0.53As/GaAs and GaAs reference cell, in order to show the better structure.
关键词： Quantum dot,solar cells,temperature effect,EQE
更新于2025-09-19 17:13:59
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Photoexcitation triggering via semiconductor Graphene Quantum Dots by photochemical doping with Curcumin versus perio-pathogens mixed biofilms
摘要： Background: Recently, antimicrobial photodynamic therapy (aPDT) as an alternative treatment modality has been used adjunctively in the treatment of periodontitis and peri-implantitis. Photosensitizing agents in the form of nanoparticles have been designed for improving the e?ciency of aPTD. Graphene quantum dots are a special type of nanocrystals that can promote aPDT when coupled with curcumin (Cur). The main objective of the present study was to investigate the e?ects of photoexcited GQD-Cur on the metabolic activity of perio-pathogen mixed bio?lms. Materials and methods: GQD-Cur was synthesized and characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible spectrometry (UV–Vis), and X-ray di?raction (XRD). The cell cytotoxicity e?ect of GQD-Cur was evaluated on primary human gingival ?broblast (HuGu) cells. Perio-pathogen mixed bio?lms including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia photosensitized with GQD doped with Cur were irradiated with a blue LED at a wavelength of 435 ± 20 nm for 1 min, and then bacterial viability measurements were performed. The antimicrobial susceptibility pro?le, bio?lm formation ability, amount of reactive oxygen species (ROS) released, and variations of gene expressions involved in bio?lm formation were assessed. Results: The SEM, DLS, FTIR, UV–Vis spectrometry, and XRD pattern con?rmed that GQD-Cur was synthesized successfully. According to the results, GQD-Cur exhibited no cytotoxicity against HuGu cells. Photoexcited GQD-Cur resulted in a signi?cant reduction in cell viability (93%) and bio?lm formation capacity (76%) of peri-pathogens compared to the control group (P < 0.05). According to the results, a signi?cant concentration-dependent increase in the ROS generation was observed in perio-pathogens mixed cells treated with di?erent doses of GQD-Cur-aPDT. Moreover, rcpA, ?mA, and inpA gene expression pro?les were downregulated by 8.1-, 9.6-, and 11.8-folds, respectively. Conclusions: Based on the results, photoexcited GQD-Cur have a high potency of perio-pathogens suppression in planktonic and bio?lm forms and downregulation of the bio?lm genes expression pattern was exploited as a nanoscale-based platform for periodontitis.
关键词： Curcumin,Antimicrobial photodynamic therapy,Graphene Quantum Dot,Peri-implantitis,Periodontitis
更新于2025-09-19 17:13:59
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Development of sulfur doped carbon quantum dots for highly selective and sensitive fluorescent detection of Fe2+ and Fe3+ ions in oral ferrous gluconate samples
摘要： Sulfur-doped carbon quantum dots (S-CQDs) with stable blue fluorescence were synthesized through a facile one-step hydrothermal method by using ascorbic acid and thioglycolic acid as carbon and sulfur sources. The prepared S-CQDs exhibited a sensitive and selective response to Fe3+ ions in comparison with Fe2+ and other metal ions, In the presence of adequate H2O2, Fe2+ was completely transformed to Fe3+ that is the determinable form of iron ions, and the difference in the change of the fluorescence intensity of S-CQDs before and after adding H2O2 was used for detection of Fe2+ ions, respectively. Under the optimum experimental conditions, the fluorescence intensity of S-CQDs gradually decreased with increasing of Fe3+ concentration ranging from 0 to 200 mM. Good linearity was achieved over the range of 0-200 mM. The detection limit of the developed method was 0.050 mM for Fe3+. The recoveries of Fe2+ spiked in real samples ranged from 98.2% to 112.4%. Finally, the proposed S-CQDs integrated with Fenton system was applied to the detection of Fe2+ and Fe3+ ions in oral ferrous gluconate samples, which presents potential applications in the speciation and determination of Fe2+ and Fe3+ ions in complex samples.
关键词： Fluorescence quenching,Iron supplement,Iron,Sulfur co-doped,Carbon quantum dot
更新于2025-09-19 17:13:59
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Air exposure oxidation and photooxidation of solution-phase treated PbS quantum dot thin films and solar cells
摘要： The air exposure oxidation mechanisms of PbS quantum dot (QD) thin films and solar cells are studied in the current paper. As a novel and advantageous method, QD thin films were prepared by the single-step deposition of colloidal QDs treated with different ligands of butylamine (BA), mercaptopropionic acid (MPA), tetra-butylammonium iodide (TBAI), methylammonium iodide (MAI) and methylammonium lead triiodide (MAPbI3, perovskite). Photoluminescence (PL) measurements evaluated the stability of different surface treated PbS QDs during the colloidal to thin film transformation, and over the air exposure times. Blue-shift and quenching the PL spectra suggested rapid oxidation of QD thin films at the first times of air exposure. However, the oxidation rates significantly reduced for the QD thin films treated with organic MPA and all the inorganic ligands. According to the X-ray photoelectron spectroscopy (XPS) studies, thin films oxidation accompanied with the formation of PbSO3 and PbSO4 compounds on the (100) facets of PbS QDs. Although MAPbI3 treatment led to the complete passivation of QDs in the air, perovskite shelling partially oxidized to PbO and PbCO3 compounds. Furthermore, the PL enhancement phenomenon observed at the first times of air exposure for the TBAI and MAPbI3-treated QD thin films, as a result of their strong surface passivation as well as the photoenhancement and photoelectrification mechanisms. Eventually, p-n and p-i-n structured solar cells were fabricated by the single-step deposition of solution-phase treated PbS QD inks. In this case, inorganic surface treatments not only increased the power conversion efficiency (PCE) of solar cells, but also led to a high stability of fabricated devices in the air environment (lower than 1% PCE loss after 500 h of storage in the air).
关键词： PbS quantum dot,Solar cell,Ligand,Photooxidation,Thin film,Air stability
更新于2025-09-19 17:13:59
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Collective topo-epitaxy in the self-assembly of a 3D quantum dot superlattice
摘要： Epitaxially fused colloidal quantum dot (QD) superlattices (epi-SLs) may enable a new class of semiconductors that combine the size-tunable photophysics of QDs with bulk-like electronic performance, but progress is hindered by a poor understanding of epi-SL formation and surface chemistry. Here we use X-ray scattering and correlative electron imaging and diffraction of individual SL grains to determine the formation mechanism of three-dimensional PbSe QD epi-SL films. We show that the epi-SL forms from a rhombohedrally distorted body centred cubic parent SL via a phase transition in which the QDs translate with minimal rotation (~10°) and epitaxially fuse across their {100} facets in three dimensions. This collective epitaxial transformation is atomically topotactic across the 103–105 QDs in each SL grain. Infilling the epi-SLs with alumina by atomic layer deposition greatly changes their electrical properties without affecting the superlattice structure. Our work establishes the formation mechanism of three-dimensional QD epi-SLs and illustrates the critical importance of surface chemistry to charge transport in these materials.
关键词： superlattice,atomic layer deposition,topotaxy,PbSe,colloidal quantum dot,epitaxial fusion
更新于2025-09-19 17:13:59