High-quality ZnS Research Articles

Controllable synthesize of ZnS/PbS nanostructure and their structural and morphological properties

ZnS is an appealing material with wide potential applications in optoelectronics, sensors, and photocatalysis due to its fascinating properties, low cost, and eco-friendly. In this paper, we report the synthesis of ZnS nanowires and nanorods via a simple thermal-evaporation method using different concentrations of PbS as a dopant. The prepared nanostrutures were investigated in detalis using a scanning electron microscopy (SEM), X-ray diffraction (XRD), and high resolution transmission electron microscopy (HRTEM). The results show that the fabricated ZnS nanowire/nanorod has a wurtzite (hcp) structure. In addition, based on the experimental results, the growth mechanism of the prepared nanostructures is reported. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray (EDX) mapping analyses confirmed that the ZnS nanorods were stoichiometric without impurities or defects, whereas PbS quantum dots were formed inside the high-quality nanowires. The formation mechanism of ZnS nanowires is discussed based on the vapor–liquid–solid (VLS) growth model. Results demonstrated that thermal evaporation is a simple and effective techniques for producing high-quality heterostructured ZnS nanowires with potential applications in different fields.

Metal–semiconductor–metal detectors ZnS/GaP for the ultraviolet and visible part of the spectrum with electrically tunable spectral photosensitivity

High-quality ZnS epitaxial layers grown on GaP semiconductor substrates by MOCVD method. Photodetectors of the visible and UV parts of the spectrum based on new interdigitated Schottky barrier metal–semiconductor–metal (MSM) contacts to semiconductor structure ZnS/GaP. The detectors exhibit low dark current values. The dependence of the characteristics of the spectral response of detectors on voltage has been established offsets. It was found that the long-wavelength response boundary of ZnS/GaP MSM detectors can shift from 355 to 450 nm when the bias voltage changes from 10 to 30 V. At the maximum photosensitivity wavelength of 450 nm, the ampere-watt sensitivity of the detector was 0.3 A/W at a bias voltage of 60 V, and the quantum efficiency was 82%.

Controllable Synthesis of Well-Monodispersed ZnS Nanospheres Through a Simple Sol–Gel Method and a Rapid Co-Phase Precipitation Method

In this study, the sol–gel method was used to prepare well-monodispersed ZnS nanopowders with a powder size of approximately 0.5 μm. The starting materials used were Zn(NO3)2 · 6H2O and C2H5NS. However, the agglomeration problem of the powders was addressed by adding an appropriate amount of (C6H9NO)n. The sol–gel method successfully produced submicron-sized ZnS powders. To further reduce the powder particle size, a rapid co-phase precipitation method was employed. This method involved using ZnCl2 and C2H5NS, which yielded ZnS nanopowders with a particle size of approximately 50 nm. The key focus of this method was on selecting the precipitating agent and emulsion to control the precipitation of ZnS nanoparticles. Both methods resulted in finer powder particle sizes and higher powder purity compared to commercial ZnS powders. These improvements in the optical and mechanical properties of ZnS IR-transmitting ceramics are significant. Overall, this study demonstrates the effectiveness of using these methods for synthesizing high-quality ZnS nanopowders.

High-quality optically defect-free 1D ZnS nanostructures by a modified thermal evaporation method

ZnS has great potential as a valuable material for nanoscale devices because of its rich morphologies and unique structure. Although much effort has been made, the growth of high-quality ZnS crystal is still a challenge. In this paper, high-quality optically defect-free 1D ZnS nanostructures, including nanorods, nanowires, and nanobelts, were successfully synthesized on a large scale by a modified thermal evaporation method. XRD patterns and HRTEM images indicated that the ZnS nanostructures are single phases with hexagonal structures. Under optical excitation, all the ZnS nanostructures show intense UV emissions and almost no defect emissions at room temperature. Sharp UV lasing-like peaks with the FWHM as narrow as 2–3 nm are achieved for the ZnS nanobelts and nanowires. The optical transition from free exciton A, free exciton B, and their associated LO phonon replicas were determined from the evolution of the NBE emissions. These high-quality nanostructures are envisaged to be highly promising for high-efficiency light-emitting devices and lasers in the UV region.

Algorithm to obtain the species distribution diagrams and solubility curves for depositing ZnS, ZnO, and Zn(OH)2 films in aqueous solution

This work presents an algorithm to obtain the species distribution diagrams and the solubility curves for a chemical bath system containing ZnCl2, NH4NO3, KOH, and SC(NH2)2 in aqueous solution. This algorithm is useful to obtain the better chemical conditions for synthesizing high quality ZnO, ZnS, or Zn(OH)2 films by the chemical bath deposition technique. The algorithm requires to identify all the formed species from the chemical reagents. The chemical conditions can be obtained in a range of temperature from 25 °C to 90 °C. The better conditions to obtain the mentioned films are explained and justified with the respective optical, morphological and structural characterizations.

Effect of seed layer on structure and luminescence properties of ZnS nanostructures

To study the influence of seed layer on the structure and luminescence properties of ZnS nanostructures, high quality ZnS nanostructures have been grown on Si substrate with and without seed layer by hydrothermal method. The ZnS seed layer was pre-deposited on Si substrate by pulsed laser deposition (PLD). It is found that the seed layer plays an important role in the growth of ZnS nanostructures. With seed layer, the lattice mismatch between ZnS nanostructure and Si substrate is effectively reduced, so the crystal quality and surface morphology of ZnS nanostructures can be greatly improved, while the luminescence intensity of ZnS nanostructures decreases along with the luminescence peak blue shift. Although reduced, the luminescence intensity is still very strong. This indicates that ZnS nanostructures have a potential application prospect in light-emitting devices.

Fabrication of metal chalcogenide thin films by a facile thermolysis process under air ambient using metal-3-mercaptopropionic acid complex

We report a facile and low-cost solution-based approach to synthesize various binary, ternary and quaternary metal chalcogenide thin films. Homogeneous metal chalcogenides single precursor is prepared by dissolving metal salt (metal chloride/acetate) in ethanolic/methanolic solution of 3-Mercaptopropionic acid (MPA) at room temperature. High-quality CdS, ZnS, Sb2S3, CuInS2 (CIS) and Cu2ZnSnS4 (CZTS) metal sulfide thin films are successfully synthesized by thermalizing these metal-MPA precursor solution at 350 °C in air for 15 min. The mechanism of metal sulfide formation is analyzed by FTIR and thermogravimetry coupled with mass spectrometry. This study highlights the formation of intermediate metal-MPA complex as a single precursor, which eventually decomposes into metal sulfide upon heating at 350 °C. The film thickness, morphology and composition of metal sulfide can be controlled by the concentration of reactants, deposition cycles and the choice of solvent. XRD, Raman, UV–vis spectroscopy, diffuse reflectance spectroscopy and energy dispersive analyses ascertain the phase purity of the films. Bandgap estimates, morphology, narrow Urbach width with low defect densities in the bandgap region, uniform thickness discerned from cross-section SEM, uniformity in the elemental maps and the photoconductivity studies further confirm high-quality of the films. Attaining molecular-level homogeneous precursor solution and inertness to the air ambient enables precise control on the stoichiometry and the enhanced uniformity of deposited films. This facile method will have potential application in large scale synthesis of different metal chalcogenide thin films by a thermolysis process and is highly suitable for controlling stoichiometry and spatial uniformity of deposited films sought in solar cell, optoelectronic and catalysis applications.

Fe-doped ZnS film fabricated by electron beam evaporation and its application as saturable absorber for Er:ZBLAN fiber laser* *Project supported by the National Natural Science Foundation of China (Grant No. U1730141).

High-quality Fe-doped ZnS films have been fabricated by electron beam evaporation. After the doping, the fabricated films still maintain the preferential crystalline orientation and phase purity of the host ZnS. According to the observation of surface morphology, the root mean-square roughness of the samples increases slightly with the increase of doping content. All of the prepared samples are in cubic zinc blende structure of ZnS. Transmission spectrum confirms a more obvious dip near 3 μm with higher dopant concentration and it can be attributed to the typical 5E→5T2 transition of Fe2+. Fe-doped ZnS film is also successfully used for Q-switched Er:ZBLAN fiber laser.

ZnO/ZnS core-shell nanostructures for hydrogen gas sensing performances

Abstract ZnO/ZnS core-shell structures were hydrothermally grown on SiO2 substrates functioning as hydrogen gas sensing chips. Results indicate that a core-shell structure with an appropriate sulfurization period of 10 min had better H2 sensing performance than those of all other growth conditions. Furthermore, multiple material characterizations revealed that ZnS with a growth time of 10 min could form high-quality and good-adherent ZnS powders with moderate thickness attached to the ZnO nanorods. Because of their small size, portability, simple fabrication and high sensitivity, ZnO/ZnS core-shell based H2 gas sensors show promise for future H2 detecting applications.

Semiconductor Nanocrystal Engineering by Applying Thiol- and Solvent-Coordinated Cation Exchange Kinetics.

Thiol- and solvent-coordinated cation exchange kinetics have been applied to engineer the composition and crystallinity of novel nanocrystals. The detailed thermodynamics and kinetics of the reactions were explored by NMR spectroscopy, time-dependent photoluminescence (PL) characterizations and theoretical simulations. The fine structure of the colloidal semiconductor nanocrystals (CSNCs) was investigated by X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). In this way, high-quality p-type Ag-doped ZnS quantum dots (QDs) and Au@ZnS hetero-nanocrystals with a cubic phase ZnS shell were synthesized successfully.The unprecedented dominant Ag+ -dopant-induced fluorescence and p-type conductivity in the zinc-blende ZnS are reported.

Improved white light emission from ZnS:Mn/ZnO/GaN core-shell nanorods array

By depositing ZnS:Mn films using PLD technique to coat ZnO nanorods which were grown on GaN substrate using hydrothermal method, high quality ZnS:Mn/ZnO/GaN core-shell nanorods array was prepared. The PL spectrum of ZnS:Mn/ZnO/GaN core-shell array ranges from blue-violet light to red light (400–700 nm). It consists of four luminous bands: UV light at 375 nm originating from the free exciton emission of ZnO, a blue light emission at 450 nm from GaN, an orange light emission at 590 nm mainly from ZnO nanorods and Mn2+ in ZnS, and a green light emission at about 530 nm related to ZnS:Mn/ZnO interface. The mechanism of green light emission is analyzed in detail. The color coordinate of ZnS:Mn/ZnO/GaN core-shell array is (0.3347, 0.318), and the color temperature is 5375 K, much closer to the standard white light when compared with other systems.

ZnS nanoparticles coated with graphene-like nano-cell as anode materials for high rate capability lithium-ion batteries

A core–shell structure ZnS nanocomposite was synthesized by wrapping ZnS nanoparticles up in graphene-like nano-cell (GLC@ZnS) through chemical vapor deposition. The morphological and structural characteristics exhibit that the obtained GLC@ZnS composite possesses high-quality ZnS nano-sized particles and laminated graphene-like layers shell. When applied as anode materials for lithium-ion batteries, the GLC@ZnS composite (high ZnS content of 97.2%) with diameter of 30 nm delivers high reversible capacities (1134 mAh g−1 after 100 cycles at 0.5 A g−1, 890 mAh g−1 after 200 cycles at 1.0 A g−1) and excellent rate capability (701 mAh g−1 at 8.0 A g−1). The excellent electrochemical performance of the composite is ascribed to the inclosed graphene-like nano-cell, which could localize the active materials and enhance the exchange of charges and ions.

Guided Growth of Horizontal ZnS Nanowires on Flat and Faceted Sapphire Surfaces

The surface-guided growth of horizontal nanowires (NWs) allows assembly and alignment of the NWs on the substrate during the synthesis, thus eliminating the need for additional processes after growth. One of the major advantages of guided growth over postgrowth assembly is the control on the NWs direction, crystallographic orientation, and position. In this study, we use the guided growth approach to synthesize high-quality, single-crystal, aligned horizontal ZnS NWs on flat and faceted sapphire surfaces, and show how the crystal planes of the different substrates affects the crystal structure and orientation of the NWs. We also show initial results of the effect of Cu doping on their photoluminescence. Such high-quality aligned ZnS NWs can potentially be assembled as key components in phosphorescent displays and markers due to their unique optical properties. The ZnS NWs have either wurtzite or zinc-blende structure depending on the substrate orientations and contain intrinsic point defects such as sulfu...

Modifications of ZnO/ZnS Core Shell Surface by Varying ZnO Seed Layer Electrodeposition Conditions

In this research, ZnO/ZnS core/shell nanostructures were grown by electro-hydrothermal methods on titanium substrates. To optimize the growth of the nanostructures, the ZnO seed layer electro-deposition time was adjusted to modify the surface of the nanostructure.Multiple material characterizations were performed to examine the surface morphologies and material properties of the nanostructures. Results indicate that ZnO/ZnS nanostructures with ZnO deposition time of 5 sec had well-grown ZnO nanorods and high-quality ZnS nanoparticles for ZnO/ZnS core shell structures. ZnO/ZnS nanostructures on titanium substrates show promising for future development of titanium substrate-based biomedical and optoelectronic devices in the future.

General strategy for embedding high quality Fe3O4 quantum dots and ZnS:Mn2+ quantum dots in a silica matrix

In this paper, ZnS:Mn2+ quantum dots (QDs) Fe3O4 quantum dots (QDs)/SiO2 nanocomposites were successfully synthesized by reverse microemulsion method. The average diameter of ZnS:Mn2+ QDs, Fe3O4 QDs and ZnS:Mn2+ QDs Fe3O4 QDs/SiO2 nanocomposites was about 5.8, 9 and 29 nm, respectively. As the mass ratio of ZnS:Mn2+ to Fe3O4 QDs increased from 2.5:4 to 7.5:4, the intensity of the yellow–orange emission coming from Mn2+ ions was increased. The superparamagnetic property of ZnS:Mn2+ QDs Fe3O4 QDs/SiO2 nanocomposites was observed at room temperature, and the saturation magnetization was decreased as the amount of ZnS:Mn2+ QDs increased.

Chemical bath deposited ZnS buffer layer for Cu(In,Ga)Se2 thin film solar cell

The dependence of Zn precursors using zinc sulfate (ZnSO4), zinc acetate (Zn(CH3COO)2), and zinc chloride (ZnCl2) on the characteristics of the chemical bath deposited ZnS thin film used as a buffer layer of Cu(In,Ga)Se2 (CIGS) thin film solar cell was studied. It is found that the ZnS film deposition rate increases with higher stability constant during decomplexation reaction of zinc ligands, which affects the crack formation and the amount of sulfur and oxygen contents within the film. The band gap energies of all deposited films are in the range of 3.40–3.49eV, which is lower than that of the bulk ZnS film due to oxygen contents within the films. Among the CIGS solar cells having ZnS buffer layers prepared by different Zn precursors, the best cell efficiency with 9.4% was attained using Zn(CH3COO)2 precursor due to increased Voc mainly. This result suggests that [Zn(NH3)4]2+ complex formation should be well controlled to attain the high quality ZnS thin films.

Sensitive prostate specific antigen quantification using dihydrolipoic acid surface-functionalized phosphorescent quantum dots

Herein, high-quality Mn-doped ZnS quantum dots (QDs) have been synthesized using a facile approach directly in aqueous media. The surface of the obtained QDs was further modified by cap-exchange of the native cysteine shell with dihydrolipoic acid (DHLA) ligands resulting in nanocrystals with high water-stability having an intense phosphorescent signal. Covalent bioconjugation of the DHLA-coated nanoparticles with an anti-IgG antibody was then carried out. Interestingly the QD immunoprobe (QD-labelled antibodies) maintained an intense phosphorescence emission, without any significant spectral-shift (as compared to the free QDs). Coupling of an asymmetric flow field flow fractionation technique to an elemental mass spectrometry detection enabled the accurate determination of the efficiency of the bioconjugation reaction.The obtained nanoparticle-antibody bioconjugate was then applied to develop a quantitative sandwich-type phosphorescent immunoassay for Prostate Specific Antigen (PSA), and a limit of detection (LOD) of 17 pg mL−1 of PSA was achieved and allow to quantify such biomarker in samples within clinically relevant levels. Finally, the assay was validated for the quantification of PSA in the cellular media of prostate cancer cells. Obtained results proved the robustness of the proposed immunoassay based on long-lived phosphorescence measurements against eventual photoluminescent interferences significantly affecting the conventional short-lived fluorescence detection.

22aB9 高品質ZnS薄膜のホモエピタキシャル成長(気相成長II)

22aB9 高品質ZnS薄膜のホモエピタキシャル成長(気相成長II)

Structural evolution and optical properties of oxidized ZnS microrods

In this study, we present a simple and versatile way to growth and modify photoemission of high quality ZnS microrods by thermal evaporation method in combination with post oxidation in oxygen environment. The as-grown ZnS microrods show strong near edge luminescence doublets at room temperature indicating the high crystalline quality. Using ultrahigh-resolution scanning electron microscope integrated with energy microanalysis and cathodoluminescence capacity we elucidate the effect of oxidation temperature on microstructure surface, chemical composition and emission spectra of ZnS microrods. Under appropriate oxidation condition, the initial high quality ZnS microrods can be converted into ZnS/ZnO microrod heterostructures or optically active porous ZnO microrods. More particularly, we demonstrate that the emission wavelength of an oxygen-related defect could be tuned in between optical band-gap of ZnS and ZnO upon increasing the oxidation temperature. This research introduces a simple approach to synthesize and tune optical property of high quality ZnS crystals.

Synthesis and optical characterization of a high-quality ZnS substrate for optoelectronics and UV solar-energy conversion

A high-grade cubic ZnS substrate crystal with longer range order and a strong band-edge emission was clearly demonstrated.