Silicon Quantum Dots Research Articles

Synthesis of N-doped and P-doped silicon quantum dots and their applications for tetracycline detection in the honey samples and antibacterial properties

The abuse of tetracycline can lead to its residue in animal derived foods, posing many potential hazards to human health. Therefore, rapid and accurate detection of tetracycline is an important means to ensure food safety. Nitrogen doped and phosphorus doped silicon quantum dots (N-SiQDs, P-SiQDs) with remarkable optical stability were fabricated via a one-pot hydrothermal procedure in this study. Upon the excitation at 346 nm, N-SiQDs and P-SiQDs emitted fluorescence at 431 nm and 505 nm, respectively. Two SiQDs had the potential to serve as a probe for detecting low concentrations of tetracycline (TC), employing a mechanism of the static quenching effect. The calibration curves of N-SiQDs and P-SiQDs were linear within the range of 0–0.8 μM and 0–0.4 μM, the limits of detection were low as 5.35 × 10−4 μmol/L and 6.90 × 10−3 μmol/L, respectively. This method could be used successfully to detect TC in honey samples. Moreover, the remarkable antibacterial efficacy of two SiQDs could be attributed to the generation of a large number of intracellular reactive oxygen species. The SEM images showed that the structure of bacterial cell was disrupted and the surface became irregular when treated with both SiQDs. These properties enabled potential usage of SiQDs as excellent antibacterial material for different biomedical applications.

Multimodule microwave assembly for fast readout and charge-noise characterization of silicon quantum dots

Multimodule microwave assembly for fast readout and charge-noise characterization of silicon quantum dots

Preparation of silicon quantum dot–protein complex and application in antibacterial, antibiofilm, and bacterial cell imaging

Preparation of silicon quantum dot–protein complex and application in antibacterial, antibiofilm, and bacterial cell imaging

Electric field dependence of spin qubit in a Si-MOS quantum dot

Abstract Valley, the intrinsic feature of silicon, is an inescapable subject in silicon-based quantum computing. At the spin–valley hotspot, both Rabi frequency and state relaxation rate are significantly enhanced. With protection against charge noise, the valley degree of freedom is also conceived to encode a qubit to realize noise-resistant quantum computing. Here, based on the spin qubit composed of one or three electrons, we characterize the intrinsic properties of valley in an isotopically enriched silicon quantum dot (QD) device. For one-electron qubit, we measure two electric-dipole spin resonance (EDSR) signals which are attributed to partial occupation of two valley states. The resonance frequencies of two EDSR signals have opposite electric field dependences. Moreover, we characterize the electric field dependence of the upper valley state based on three-electron qubit experiments. The difference of electric field dependences of the two valleys is 52.02 MHz/V, which is beneficial for tuning qubit frequency to meet different experimental requirements. As an extension of electrical control spin qubits, the opposite electric field dependence is crucial for qubit addressability, individual single-qubit control and two-qubit gate approaches in scalable quantum computing.

Efficient Full-Frequency GW Calculations Using a Lanczos Method.

The GW approximation is widely used for reliable and accurate modeling of single-particle excitations. It also serves as a starting point for many theoretical methods, such as its use in the Bethe-Salpeter equation (BSE) and dynamical mean-field theory. However, full-frequency GW calculations for large systems with hundreds of atoms remain computationally challenging, even after years of efforts to reduce the prefactor and improve scaling. We propose a method that reformulates the correlation part of the GW self-energy as a resolvent of a Hermitian matrix, which can be efficiently and accurately computed using the standard Lanczos method. This method enables full-frequency GW calculations of material systems with a few hundred atoms on a single computing workstation. We further demonstrate the efficiency of the method by calculating the defect-state energies of silicon quantum dots with diameters up to 4nm and nearly 2,000 silicon atoms using only 20 computational nodes.

Valley splitting depending on the size and location of a silicon quantum dot

Valley splitting depending on the size and location of a silicon quantum dot

Green Synthesis of Silicon Quantum Dots Using Ocimum basilicum var. Purpurascens as an Organic Reductor Agent

Green Synthesis of Silicon Quantum Dots Using Ocimum basilicum var. Purpurascens as an Organic Reductor Agent

Non-symmetric Pauli spin blockade in a silicon double quantum dot

Spin qubits in gate-defined silicon quantum dots are receiving increased attention thanks to their potential for large-scale quantum computing. Readout of such spin qubits is done most accurately and scalably via Pauli spin blockade (PSB), however, various mechanisms may lift PSB and complicate readout. In this work, we present an experimental study of PSB in a multi-electron low-symmetry double quantum dot (DQD) in silicon nanowires. We report on the observation of non-symmetric PSB, manifesting as blockaded tunneling when the spin is projected to one QD of the pair but as allowed tunneling when the projection is done into the other. By analyzing the interaction of the DQD with a readout resonator, we find that PSB lifting is caused by a large coupling between the different electron spin manifolds of 7.90 μeV and that tunneling is incoherent. Further, magnetospectroscopy of the DQD in 16 charge configurations, enables reconstructing the energy spectrum of the DQD and reveals the lifting mechanism is energy-level selective. Our results indicate enhanced spin-orbit coupling which may enable all-electrical qubit control of electron spins in silicon nanowires.

In Vivo Assessment of Hepatic and Kidney Toxicity Induced by Silicon Quantum Dots in Mice.

In the last decade, silicon-based quantum dots (SiQDs) have attracted the attention of researchers due to their unique properties for which they are used in medical applications and in vivo imaging. Detection of cytotoxic effects in vivo is essential for understanding the mechanisms of toxicity, a mandatory step before their administration to human subjects. In this context, we aimed to evaluate the in vivo hepatic and renal acute toxicity of SiQDs obtained by laser ablation. The nanoparticles were administrated at different doses (0, 1, 10, and 100 mg of QDs/kg of body weight) by intravenous injection into the caudal vein of Swiss mice. After 1, 6, 24, and 72 h, the animals were euthanatized, and liver and kidney tissues were used in further toxicity tests. The time- and dose-dependent effects of SiQDs on the antioxidant defense system of mice liver and kidney were investigated by quantifying the activity of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase) in correlation with the morphological changes and inflammatory status in the liver and kidneys. The results showed a decrease in the activities of antioxidant enzymes and histopathological changes, except for superoxide dismutase, in which no significant changes were registered compared with the control. Furthermore, the immunohistochemical expression of TNF-α was significant at doses over 10 mg of QDs/kg of body weight and were still evident at 72 h after administration. Our results showed that doses under 10 mg of SiQDs/kg of b.w. did not induce hepatic and renal toxicity, providing useful information for further clinical trials.

Cryogenic flip-chip interconnection for silicon qubit devices

Interfacing qubits with peripheral control circuitry poses one of the major common challenges toward realization of large-scale quantum computation. Spin qubits in silicon quantum dots (QDs)are particularly promising for scaling up, owing to the potential benefits from the know-how of the semiconductor industry. In this paper, we focus on the interposer technique as one of the potential solutions for the quantum–classical interface problem and report DC and RF characterization of a silicon QD device mounted on an interposer. We demonstrate flip-chip interconnection with the qubit device down to 4.2 K by observing Coulomb diamonds. We furthermore propose and demonstrate a laser-cut technique to disconnect peripheral circuits no longer in need. These results may pave the way toward system-on-a-chip quantum–classical integration for future quantum processors.

Long Time Atmospheric Oxidation Followed by Hydrofluoric Etching and Hydrosilylation for High‐Efficiency Light‐Emitting Silicon Quantum Dots

AbstractTunable emission wavelength and excellent biocompatibility have positioned silicon quantum dots (Si QDs) as important optoelectronic materials in areas like displays, lighting, and biomedical imaging. However, the challenges of low luminescence efficiency impede the utilization of Si QDs, restraining the advancement of Si QDs‐based light‐emitting diode (LED) devices. This study primarily concentrates on optimizing the surface structure of Si QDs and refining the Si QDs‐based LED device structures. A strategy involving active oxidation followed by hydrofluoric etching and hydrosilylation is proposed to enhance the optical characteristics of Si QDs. A variety of characterization methods are employed to evaluate the impact of the active oxidation on the photoluminescence and surface structures of Si QDs. This approach ultimately achieves an impressive enhancement in the photoluminescence quantum yield (PL QY) of Si QDs from 6.7% to 60.3%. Furthermore, the atmospherically oxidized Si QDs with the highest PL QY are selected as the emitting‐layer material to fabricate LEDs with the structure of ITO/PEDOT:PSS/TFB/Si QDs/ZnMgO/Ag. The introduction of ZnMgO effectively balances charge injection in the Si‐QDs‐based LEDs. As a result, the devices achieve electroluminescence with an external quantum efficiency of 13.2%.

Development of Novel Silicon Quantum Dots and Their Potential in Improving the Enhanced Oil Recovery of HPAM.

Hydrolyzed polyacrylamide (HPAM) is commonly used in polymer flooding, however, it is prone to viscosity reduction at high temperatures and high salinities, weakening its ability to improve oil recovery. In this work, sulfonated modified silicon quantum dots (S-SiQDs) were synthesized and then added to HPAM to study the improvement of rheological properties and enhanced oil recovery performance of HPAM at high temperatures and salinities. It is found that the S-SiQDs with a concentration of only 0.1 wt % can significantly increase the viscosity of HPAM from 28.5 to 39.6 mPa·s at 60 °C and 10,000 mg/L NaCl. Meanwhile, the HPAM/S-SiQDs hybrid solution always possessed higher viscosity and viscoelastic moduli than HPAM, attributed to the hydrogen bonding between HPAM and S-SiQDs. Notably, HPAM/S-SiQDs still maintained elastic behavior at harsh conditions, indicating that they formed a strong network structure. Through oil displacement experiments, it was found that the oil recovery of HPAM/S-SiQDs was higher (28.3%), while that of HPAM was only 17.2%. Thereafter, the utilization sequence of oil during the displacement process was studied with nuclear magnetic resonance experiments. Ultimately, the oil displacement mechanism of HPAM/S-SiQDs was deeply analyzed, including viscosity thickening and wetting reversal.

L-Methionine and D-Methionine Capped Fluorescent Silicon Quantum Dots Based Probes for Turn on Sensing of Glutathione - A Comparative Study.

Oral Squamous Cell Carcinoma (OSCC), a prevalent type of oral cancer originates in squamous cells that develop due to tobacco use, excess alcohol consumption, human papillomavirus infection, chronic irritation and weakened immune system. When detected early, survival rates of OSCC can be increased to more than 85%. Hence its early detection is crucial for appropriate management. Oxidative stress has a vital role in pathogenesis of various cancers including OSCC. Early detection of OSCC can be done by exploring serum Glutathione (GSH); an oxidative stress biomarker. Herein, we have developed two Silicon quantum dots (SiQDs); (L-methionine capped Silicon quantum dots (LSiQDs) and D-methionine capped Silicon quantum dots (DSiQDs)) and their fluorescence was quenched with Cu2+. The obtained Cu@LSiQDs and Cu@DSiQDs were then explored and compared for sensing GSH. Both the SiQDs were checked for selectivity and interference studies using coexisting biomolecules extended for sensing GSH from real samples. Moreover, a paper strip assay was also developed and compared.

A New Type of Quantum Fertilizer (Silicon Quantum Dots) Promotes the Growth and Enhances the Antioxidant Defense System in Rice Seedlings by Reprogramming the Nitrogen and Carbon Metabolism.

To promote the growth and yield of crops, it is necessary to develop an effective silicon fertilizer. Herein, a new type of 2 nm silicon quantum dot (SiQD) was developed, and the phenotypic, biochemical, and metabolic responses of rice seedlings treated with SiQDs were investigated. The results indicated that the foliar application of SiQDs could significantly improve the growth of rice seedlings by increasing the uptake of nutrient elements and activating the antioxidative defense system. Furthermore, metabolomics revealed that the supply of SiQDs could significantly up-regulate several antioxidative metabolites (oxalic acid, maleic acid, glycine, lysine, and proline) by reprogramming the nitrogen- and carbon-related biological pathways. The findings provide a new strategy for developing an effective and promising quantum fertilizer in agriculture.

Tunability of Size, B Doping and Organic Molecular Coupling to Electronic and Optical Properties of Silicon Quantum Dots

Tunability of Size, B Doping and Organic Molecular Coupling to Electronic and Optical Properties of Silicon Quantum Dots

Preparation of silicon quantum dots@star like bloc-copolymer (SiQD@S-BP) colloidal nanoclusters through in-situ reduction and confined growth

Here in this work, colloidal nanocrystal clusters (CNCs) formed by silicon quantum dots and star-like block-copolymers (SiQDs@S-BP) were prepared through in-situ reduction and confined growth method. Water-soluble star-like block copolymer β-CD-g-PAA-b-POEGA (unimolecular micelle) was precisely synthesized through ATRP and used as the templates for SiQDs@S-BP. Owing to the electrostatic interaction, the amino groups functionalized silicon can be adsorbed to the carboxyl groups in the polymer chains. After in-situ reduction and confined growth, silicon quantum dots were formed and monodispersed in the unimolecular micelles. Benefitting from the CNCs structure, the fluorescence emission of the SiQDs enhanced due to the aggregation induced emission enhancement (AIEE) effect. The inner structure and outer polymer brushes of the CNCs avoided the coalescence of SiQDs during application and collection, and made it more efficient in recycling and reusing.

RETRACTED: Nanoscale silicon porous materials for efficient hydrogen storage application

The increasing energy demand and the worldwide energy crisis must be met in large part via the sustainable growth of hydrogen energy, since this economy is relied upon to provide clean and carbon-free energy carriers. It is anticipated that the growing demand for light and heavy fuel cell cars would stimulate the development of onboard solid-state hydrogen technology. The research here concentrates on the importance of various permeable substances such as polymers in general, metallic substances, and complex metal hydrides, even if Si nanostructures (SiNSs) have become known as the obvious contender for solid-state hydrogen storage systems. SiNSs have gained prominence as a leading candidate for solid-state hydrogen storage systems. Renowned for their high storage capacity, SiNSs, including silicon nanowires and quantum dots, exhibit promising potential in addressing challenges associated with traditional hydrogen storage methods, positioning them as a key player in advancing clean and efficient energy storage technologies. SiNSs play a crucial role in advancing solid-state hydrogen storage technology. SiNSs, including silicon nanowires and quantum dots, exhibit high storage capacity. Despite challenges like surface oxidation, SiNS holds promise for efficient hydrogen storage, contributing to the development of sustainable energy solutions and mitigating the environmental impact associated with conventional automotive technologies. We focus on the processes that result in permeable silicon, nanowires made of porous silicon, and Si quantum dots. This investigation elucidates the characteristics and patterns of hydrogen's aid, the value of hydrogen power in automobiles for reducing global warming occurrences, and the potential of using SiNSs for hydrogen storage in tandem with other forms of transition and alkali earth materials to meet these difficulties. It demonstrates how catalysts are critical to fixing the current reversibility and desorption problems with hydrogen energy storage. As a result of the analysis, energy suppliers and Si-based fuel cells may be better able to tailor their services to individual customers' needs, which might boost the growth of the hydrogen energy industry.

Bright silicon quantum dot synthesis and LED design: insights into size–ligand–property relationships from slow- and fast-band engineering

Abstract Multicolor, bright silicon quantum dots (SiQDs)—SiQDs with photoluminescence in a range of colors and quantum yields (PLQYs) of >90%—are promising heavy-metal-free light sources for full-color displays, lighting, and biomedical imaging. Colloidal SiQDs can be used to manufacture devices via printing and roll-to-roll processing. Furthermore, the in vivo use of biodegradable SiQDs and Si nanomaterials, for imaging cancer cells and as drug delivery systems, has been demonstrated. However, a large body of research demonstrates that the photoluminescence (PL) wavelength and PLQY of colloidal SiQDs are dependent not only on the SiQD particle size but also on the methods and/or procedures and chemical reagents used to synthesize them. This is because SiQDs are quite sensitive to both the intrinsic properties of Si and external factors. These intrinsic and external factors can be respectively linked to different PL mechanisms: the quantum confinement effect, which produces a slow-decaying “S”-band PL signal, and surface ligand effects, corresponding to fast-decaying “F”-band PL. This review focuses on mechanistic insights into the relationships linking the structures, ligands, and optical properties of SiQDs. Synthesis methods and the application performance of bright multicolor colloidal SiQDs, based on excellent state-of-the-art experimental and theoretical studies, are also reviewed.

Not all silicon quantum dots are equal: photostability of silicon quantum dots with and without a thick amorphous shell.

Luminescent colloidal silicon quantum dots (SiQDs) are sustainable alternatives to metal-based QDs for various optical applications. While the materials are reliant on their photoluminescence efficiency, the relationship between the structure and photostability of SiQDs is yet to be well studied. An amorphous silicon (a-Si) shell was recently discovered in SiQDs prepared by thermally-processed silicon oxides. As a-Si is known as a source of defects upon UV irradiation, the disordered shell could potentially have an adverse effect on the optical properties of nanoparticles. Herein, the photostability of ∼5 nm diameter SiQDs with an amorphous shell was compared with that of over-etched SiQDs of equivalent dimensions that bore an a-Si shell of negligible thickness. An UV-induced degradation study was conducted by subjecting toluene solutions of SiQDs to 365 nm light-emitting diodes (LEDs) under an inert atmosphere for predetermined times up to 72 hours. The structure, composition, and optical responses of the exposed SiQDs were evaluated.

Towards Atomic Scale Quantum Dots in Silicon: An Ultra-Efficient and Robust Subtractor Using Proposed P-Shaped Pattern

Towards Atomic Scale Quantum Dots in Silicon: An Ultra-Efficient and Robust Subtractor Using Proposed P-Shaped Pattern