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Single photon interference between bidirectionally extracted photons originating from semiconductor quantum dots
摘要： We report the experimental demonstration of the single-photon interference of bidirectionally extracted photons from epitaxially grown semiconductor quantum dots. The quantum dots were directly connected to single-mode optical fibers. Single-photon nature between transmission and reflection directions was confirmed through detection of antibunching in second-order photon correlation measurements. A Mach–Zehnder interferometer that was naturally formed by introducing the two outputs into a 2 x 2-fiber coupler was used to perform first-order photon correlation measurements.
关键词： single photon interference,single-mode optical fibers,Mach–Zehnder interferometer,semiconductor quantum dots
更新于2025-09-23 15:21:01
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Black Phosphorus Quantum Dots in Aqueous Ethylene Glycol for Macroscale Superlubricity
摘要： In this study, black phosphorus quantum dots (BPQDs) have been successfully prepared at a low cost and high yield by liquid-based high energy ball milling method. The obtained BPQDs with an average lateral size of 6.5 ± 3 nm and a thickness of 3.4 ± 2.6 nm dispersed stably in ethylene glycol (EG). A robust macroscale superlubricity state (μ: 0.002) was achieved under a high contact pressure of 336 MPa via the lubrication of BPQDs-EG aqueous suspension (BPQDs-EGaq) at the Si3N4/sapphire frictional interface. The wear rate lubricated by BPQDs-EGaq suspension account for 5.96% of that lubricated by EG aqueous solution (EGaq), demonstrating the improvement in the anti-wear property with the addition of BPQDs. The rolling effect of BPQDs and the low shear stress between the BPQDs interlamination played important roles in the improvement in the anti-wear property. The oxidative products of BPQDs (PxOy) contributed to the effective realization of macroscale superlubricity. This work realized macroscale superlubricity at a high contact pressure by combining the BPQDs with special liquid molecules and provided the great potential in industrial applications.
关键词： Interface,Black phosphorus quantum dots,Mixed lubrication,high contact pressure,Liquid macroscale superlubricity
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Inserting a Low-Refractive-Index Dielectric Rear Reflector into PERC Cells: Challenges and Opportunities
摘要： Light emitting devices based on Si quantum dots/SiO2 multilayers with dot size of 2.5 nm have been prepared. Bright white light emission is achieved under the dc driving conditions and the turn-on voltage of the device is as low as 5 V. The frequency-dependent electroluminescence intensity was observed under ac conditions of square and sinusoidal wave. It was found that the emission wavelength changes with frequency when sinusoidal ac is applied. The degradation of emission intensity is less than 12% after 3 h for ac driving condition, exhibiting the better device stability compared to the dc driving one.
关键词： electroluminescence (EL),Direct current (dc),Si quantum dots (Si QDs),frequency dependent
更新于2025-09-23 15:21:01
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Microstructure characteristics of non-monodisperse quantum dots: On the potential of transmission electron microscopy combined with X-ray diffraction
摘要： Although the concept of quantum confinement was introduced more than thirty years ago, a wide application of the quantum dots is still limited by the fact that monodisperse quantum dots with controlled optoelectronic properties are typically synthesized on a relatively small scale. Larger scale synthesis techniques are usually not able to produce monodisperse nanoparticles yet. In this contribution, we illustrate the capability of the combination of transmission electron microscopy and X-ray diffraction to reveal detailed and scale-bridging information about the complex microstructure of non-monodisperse quantum dots, which is the first step towards a further upscalling of the techniques for production of quantum dots with controlled properties. As a model system, CdSe quantum dots synthesized using an automated robotic hot-injection method at different temperatures were chosen. The combined microstructure analytics revealed the size and shape of the CdSe nanocrystals and the kind, density and arrangement of planar defects. The role of the planar defects in the particle coarsening by oriented attachment and the effect of the planar fault arrangement on the phase constitution, on the crystallographic coherence of the counterparts and on the optoelectronic properties are discussed.
关键词： microstructure,optoelectronic properties,planar defects,transmission electron microscopy,X-ray diffraction,quantum dots,oriented attachment,CdSe
更新于2025-09-23 15:21:01
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Hydrogen Sulfide Gas Sensor Based on Titanium Dioxide/Amino-Functionalized Graphene Quantum Dots Coated Photonic Crystal Fiber
摘要： A novel photonic crystal fiber (PCF) Mach-Zehnder interferometer (MZI) was proposed for detecting hydrogen sulfide (H2S) gas. Two single-mode fibers (SMFs), two multi-mode fibers (MMFs), and a PCF are sequentially fused to form a MZI with SMF-MMF-PCF-MMF-SMF structure. Titanium dioxide/amino-functionalized graphene quantum dots (TiO2/af-GQDs) composite is coated on the surface of PCF as sensing membrane. The fabricated sensing membrane is characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore, the properties of the sensor are examined. The results show that a uniform TiO2/af-GQDs film with a thickness of 1 μm is successfully coated on the surface of the PCF. The sensor has a sensitivity of 26.62 pm/ppm, showing a good linearity and selectivity for H2S in the range of 0~55 ppm. The response time and recovery time are about 68 s and 77 s, respectively. The sensor has the advantages of low cost, small volume and simple structure, which is suitable for on-line monitoring of H2S.
关键词： Mach-Zehnder interference,Graphene quantum dots,Titanium dioxide,Fiber-optic sensing,Hydrogen sulfide
更新于2025-09-23 15:21:01
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Excitation Transfer in Hybrid Nanostructures of Colloidal Ag2S/TGA Quantum Dots and Indocyanine Green J-Aggregates
摘要： The regularities of the electron excitations exchange in hybrid associates of colloidal Ag2S quantum dots, passivated with thioglycolic acid (Ag2S/TGA QDs) with an average size of 2.2 and 3.7 nm with Indocyanine Green J-aggregates (ICG) were studied in this work by methods of absorption and luminescence spectroscopy. It was shown that IR luminescence sensitization of Ag2S/TGA QDs with an average size of 3.7 nm in the region of 1040 nm is possible due to non-radiative resonance energy transfer from Ag2S/TGA QDs with an average size of 2.2 nm and luminescence peak at 900 nm using ICG J-aggregate as an exciton bridge. The sensitization efficiency is 0.33. This technique provides a transition from the first therapeutic window (NIR-I, 700-950 nm) to the second (NIR-II, 1000-1700 nm). It can allow high to increase the imaging in vivo resolution.
关键词： Non-radiative resonance energy transfer (FRET),Indocyanine green,Hybrid associate,Luminescence properties,Silver sulfide quantum dots,J-aggregates
更新于2025-09-23 15:21:01
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Autonomous Tuning and Charge-State Detection of Gate-Defined Quantum Dots
摘要： Defining quantum dots in semiconductor-based heterostructures is an essential step in initializing solid-state qubits. With growing device complexity and increasing number of functional devices required for measurements, a manual approach to finding suitable gate voltages to confine electrons electrostatically is impractical. Here, we implement a two-stage device characterization and dot-tuning process, which first determines whether devices are functional and then attempts to tune the functional devices to the single or double quantum-dot regime. We show that automating well-established manual-tuning procedures and replacing the experimenter’s decisions by supervised machine learning is sufficient to tune double quantum dots in multiple devices without premeasured input or manual intervention. The quality of measurement results and charge states are assessed by four binary classifiers trained with experimental data, reflecting real device behavior. We compare and optimize eight models and different data preprocessing techniques for each of the classifiers to achieve reliable autonomous tuning, an essential step towards scalable quantum systems in quantum-dot-based qubit architectures.
关键词： semiconductor qubits,autonomous tuning,machine learning,quantum dots
更新于2025-09-23 15:21:01
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Excitonic complexes in InAs/InP nanowire quantum dots
摘要： InAs quantum dots embedded in InP nanowires form an important platform for basic research studies, as well as for quantum dot applications. Notably, understanding of nanowire quantum dot spectral properties is essential in both cases. Therefore, in this work we use atomistic theory to study spectra of the single exciton (X ), the biexciton (X X ), the triexciton (X X X ), and the positively and negatively charged trions (X + and X ?) con?ned in these nanostructures. We focus on the role of vertical and lateral con?nement, therefore, we systematically study a large family of quantum dots with different heights and diameters, and ?nd the important role of correlations due to presence of higher states. We ?nd that the order of excitonic binding energies is a characteristic feature of InAs/InP nanowire quantum dots being (ordered from negative to positive values): X ?, X X , and X +, with strongly bound X ?, rather weakly bound X X , and typically unbound X +. Next, we determine the key role of alloy randomness due to intermixing, which turns out to especially important for larger quantum dot heights and phosphorous contents over 40%. In selected cases, the alloying can lead to an unbound biexciton, and can even reverse ordering of excitonic lines.
关键词： InAs/InP nanowire quantum dots,atomistic theory,binding energies,alloy randomness,excitonic complexes
更新于2025-09-23 15:21:01
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[IEEE 2019 20th International Conference on Electronic Packaging Technology(ICEPT) - Hong Kong, China (2019.8.12-2019.8.15)] 2019 20th International Conference on Electronic Packaging Technology(ICEPT) - Micro-dimple/pillar array molded by a track-etching mold for improving the optical performance of quantum dot film
摘要： Recently, phosphor films have been widely used in display, illumination and other fields. Methods of fabricating structures on phosphor films to enhance their optical properties have attracted great attention in academia and industry. Current methods to fabricate a structured film are mainly by imprinting techniques. However, crystalline silicon or a patterned sapphire substrate are applied to the transfer substrate, which is cumbersome and expensive. This paper describes a track-etching mold, prepared by bombarding a polycarbonate film (PC) with high-speed particles to form phosphor film with microporous structure，which also has a transfer effect. The process is simple and efficient. Simultaneously, the micro-pillar structure PDMS film (MPS-PDMS film) transferred by the PC film has a discrete distribution of micro-pillar structures. Their optical performance was measured and the haze was improved by 12.06% compared with the unstructured PDMS film (US- PDMS film). Subsequently, the micro-dimples structure quantum dots film (MDS-QDs film) was secondarily fabricated using the MPS-PDMS film to have a dimple structure. The red optical power of MDS-QDs film was improved by 7.7% as compared with the unstructured quantum dot film (US-QDs film). Therefore, the structural QD films shows great potential value in luminance and display.
关键词： Track-etching mold,Quantum dots film,Microstructure fabrication,Optical power
更新于2025-09-23 15:21:01
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Quantum dots encapsulated with curcumin inhibit the growth of colon cancer, breast cancer and bacterial cells
摘要： Aim: To synthesize and examine the impact of free Eudragit R(cid:2) RS 100 nanoparticles (LN01), Quantum dots curcumin-loaded Eudragit RS 100 nanoparticles (LN04), and un-encapsulated curcumin nanoparticles (LN06) on cancerous and bacterial cells. Materials & methods: The LN01, LN04, LN06 were synthesized and characterized by Fourier transform infrared, ζ potential, UV–Vis spectroscopy, transmission electron microscopy and scanning electron microscopy and their biological activities were evaluated. Results: LN04 profoundly inhibited the growth of colon (HCT-116) cancerous cells (10.64% cell viability) and breast cancer (MCF-7) cells (10.32% cell viability) with compared to LN01 and LN06. Normal cells (HEK-293) did not show any inhibition after treatments. In addition, LN04 show better inhibitory action on bacterial growth compared with LN01 and LN06. Conclusion: We suggest that LN04 selectively target cancerous and bacterial cells and therefore possess potential anticancer and antibacterial capabilities.
关键词： quantum dots,curcumin,antibacterial agent,drug delivery,anticancer agent
更新于2025-09-23 15:21:01