Household air pollution exposure can lead to various diseases, including stroke, ischaemic heart disease, chronic obstructive pulmonary disease (COPD), and lung cancer. In this study, an indoor air purification technique was developed employing a visible light-activated photocatalyst consisting of a WO3/Pt-coated ceramic foam filter (CFF). Under visible light irradiation, the coated porous filter was able to decompose toluene, a prevalent indoor air contaminant. The interconnected three-dimensional structure of the CFF with open pores facilitated toluene adsorption and simultaneous decomposition by the photocatalyst. XRD analysis revealed that WO3/Pt had tungsten oxide in a monoclinic crystal structure with immiscible platinum metal clusters. The specific surface area and pore diameter were analyzed using the BET method, while the energy band gap was determined using DRS. XRF spectroscopy was used to find the percentage composition of the material, and structural and morphological studies of the samples were conducted using TEM and FESEM analyses. Photodegradation studies were performed for toluene removal, demonstrating a significant drop in toluene concentration in a short period (99.1% degradation in 150 min). A comparative investigation of the visible light photoactivity of WO3/Pt and TiO2 (P25) in water was conducted utilizing dye degradation tests, and WO3/Pt dominated with its excellent degradation efficiency.

Green synthesis from plant waste involves the generation of functional nanoparticles (NPs), offering significant potential for a wide range of applications. Numerous studies have focused on the use of plant extracts to produce AuNPs suitable for various applications in the medical field, particularly in photothermal therapy and cancer therapy, owing to their plasmonic properties. Moreover, NP-mediated immunostimulation and immunosuppression is an intriguing field of research, focusing on how manipulation of NP physicochemical properties can influence their inter-action with immune cells and immune modulation. However, to date, few investigations have been conducted on the modulation of the inflammatory response mediated by green-synthesized nanostructures. To this aim, we synthesized AuNPs using extracts of Laurus nobilis, which exhibit high crystallinity and are inherently coated by a dense network of polyphenols, thus maintaining stability on their surface through the green synthesis approach. Then, in order to explore how these green-synthesized nanostructures can enhance or suppress the inflammatory cellular responses, we investigated the response of free polyphenols and AuNPs@polyphenols in murine bone marrow derived dendritic cells (BMDCs), by means of morphomechanical analysis and biochemical assays. Our findings demonstrated that DCs exposed to both free polyphenol extract and AuNPs@polyphenols were able to inhibit the secretion of crucial inflammatory mediators in response to lipopolysaccharide (LPS) administration. Therefore, polyphenols immobilized on Au surface were more effective in the inflammation suppression. These evidence paving the way for a powerful strategy to develop edible anti-inflammatory adjuvants, overcoming the limitations associated with the use of free polyphenols in clinical practice.

Solid state light sources irradiating in the UV spectral region are key components in today technologies as they can replace conventional mercury vapor gas-discharge lamps. Ultrathin GaN layers in AlGaN barriers are of great interest for UV-emitting photonic devices, but a detailed understanding of the exciton features of these systems is still lacking. In this work, ultrathin GaN layers, grown by metal organic chemical vapour deposition, were deeply investigated in AlGaN barriers with different Al amount, in order to correlate excitonic effects with structural features.

A dual soft-templating method was developed to produce highly crystalline and mesoporous TiO2-SiO2 nanocomposites. Pluronic F127 as the structure-directing agent and pure cellulose as the surface area modifier were used as the templating media. While Pluronic F127 served as the sacrificing media for generating a mesoporous structure in an acidic pH, cellulose templating helped to increase the specific surface area without affecting the mesoporosity of the TiO2-SiO2 nanostructures. Calcination at elevated temperature removed all the organics and formed pure inorganic TiO2-SiO2 composites as revealed by TGA and FTIR analyses. An optimum amount of SiO2 insertion in the TiO2 matrix increased the thermal stability of the crystalline anatase phase. BET surface area measurement along with low angle XRD revealed the formation of a mesoporous structure in the composites. The photocatalytic activity was evaluated by the degradation of Rhodamine B, Methylene Blue, and 4-Nitrophenol as the model pollutants under solar light irradiation, where the superior photo-degradation activity of Pluronic F127/cellulose templated TiO2-SiO2 was observed compared to pure Pluronic templated composite and commercial Evonik P25 TiO2. The higher photocatalytic activity was achieved due to the higher thermal stability of the nanocrystalline anatase phase, the mesoporosity, and the higher specific surface area.

Resistive switching (RS) induced by electrical bias is observed in numerous materials, including 2D hexagonal boron nitride (hBN), which has been used in resistive random access memories (RRAMs) in recent years. For practical high-density, cross-point memory arrays, compared with bipolar memories, nonpolar (or unipolar) devices are preferable in terms of peripheral circuit design and storage density. The non-volatile nonpolar RS phenomenon of hBN-based RRAMs with Ti/hBN/Au structure as a prototype is reported. Stable manual DC switching for approximate to 10(3) cycles with an average window over five orders of magnitude is demonstrated. After identifying a possible mechanism related to the Joule heat that contributes to the rupture of conductive filaments in nonpolar RS operations, this mechanism is validated by analyzing the occurrence of the "Re-set" process. Though the intriguing physical origin still requires more comprehensive studies, the achievement of nonpolar RS should make it more feasible to use hBN in practical RRAM technology.

Hexagonal boron nitride (h-BN) has been considered a promising dielectric for two-dimensional (2D) material-based electronics due to its atomically smooth and charge-free interface with an in-plane lattice constant similar to that of graphene. Here, we report atomic layer deposition of boron nitride (ALD-BN) using BCl3 and NH3 precursors directly on thermal SiO2 substrates at a relatively low temperature of 600 °C. The films were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and transmission electron microscopy wherein the uniform, atomically smooth, and nanocrystalline layered-BN thin film growth is observed. The growth rate is ∼0.042 nm/cycle at 600 °C, a temperature significantly lower than that of h-BN grown by chemical vapor deposition. The dielectric properties of the ALD-BN measured from Metal Oxide Semiconductor Capacitors are comparable with that of SiO2. Moreover, the ALD-BN exhibits a 2-fold increase in carrier mobility of graphene field effect transistors (G-FETs/ALD-BN/SiO2) due to the lower surface charge density and inert surface of ALD-BN in comparison to that of G-FETs fabricated on bare SiO2. Therefore, this work suggests that the transfer-free deposition of ALD-BN on SiO2 may be a promising candidate as a substrate for high performance graphene devices.

The prolonged bias stress of ZnO TFTs transistors with Al 2 O 3 deposited at 100, 175, and 250°C is presented. Fully patterned bottom gated and top contacted devices serve as the test structures. The reliability study shows increasing threshold voltage shifting of 10.5, 18.6, and 27.2 % with deposition temperature with no significant change in the density of interface states for all the samples. Nevertheless, there is a dependence of the oxide trap states with stress time. The analysis of the transconductance as a function of the threshold voltage shifting indicates that oxide traps states near the interface are the dominant instability mechanism for significant stress times. The Al 2 O 3 deposited at a temperature of 100 °C contains a higher concentration of oxygen compared to the other samples. This present oxygen excess could be filling oxygen vacancies present in the Al 2 O 3 , thereby resulting in a smaller ΔV TH .

Smooth 200 nm thick N-polar InGaN films were grown by metal–organic chemical vapor deposition (MOCVD) on sapphire using a digital approach consisting of a constant In, Ga, and N precursor flow with pulsed injection of H2 into the N2 carrier gas. Using this growth scheme, the H2 injection time was altered and the effect on the morphology and indium incorporation in the films observed. The effect of periodic insertion of additional GaN inter-layers on the surface morphology of the InGaN layers was also studied.

We report an excellent growth behavior of a high-κ dielectric on ReS2, a two-dimensional (2D) transition metal dichalcogenide (TMD). The atomic layer deposition (ALD) of an Al2O3 thin film on the UV-Ozone pretreated surface of ReS2 yields a pinhole free and conformal growth. In-situ half-cycle X-ray photoelectron spectroscopy (XPS) was used to monitor the interfacial chemistry and ex-situ atomic force microscopy (AFM) was used to evaluate the surface morphology. A significant enhancement in the uniformity of the Al2O3 thin film was deposited via plasma-enhanced atomic layer deposition (PEALD), while pinhole free Al2O3 was achieved using a UV-Ozone pretreatment. The ReS2 substrate stays intact during all different experiments and processes without any formation of the Re oxide. This work demonstrates that a combination of the ALD process and the formation of weak S–O bonds presents an effective route for a uniform and conformal high-κ dielectric for advanced devices based on 2D materials.

The interconnect half-pitch size will reach ≈20 nm in the coming sub-5 nm technology node. Meanwhile, the TaN/Ta (barrier/liner) bilayer stack has to be >4 nm to ensure acceptable liner and diffusion barrier properties. Since TaN/Ta occupy a significant portion of the interconnect cross-section and they are much more resistive than Cu, the effective conductance of an ultrascaled interconnect will be compromised by the thick bilayer. Therefore, 2D layered materials have been explored as diffusion barrier alternatives. However, many of the proposed 2D barriers are prepared at too high temperatures to be compatible with the back-end-of-line (BEOL) technology. In addition, as important as the diffusion barrier properties, the liner properties of 2D materials must be evaluated, which has not yet been pursued. Here, a 2D layered tantalum sulfide (TaSx ) with ≈1.5 nm thickness is developed to replace the conventional TaN/Ta bilayer. The TaSx ultrathin film is industry-friendly, BEOL-compatible, and can be directly prepared on dielectrics. The results show superior barrier/liner properties of TaSx compared to the TaN/Ta bilayer. This single-stack material, serving as both a liner and a barrier, will enable continued scaling of interconnects beyond 5 nm node.

Strong stabilization and localization understandings of ultra-small ∼1 nm Au/MOF hybrid materials by hydrogen evolution reaction.

Sc has been employed as an electron contact to a number of two-dimensional (2D) materials (e.g. MoS2, black phosphorous) and has enabled, at times, the lowest electron contact resistance. However, the extremely reactive nature of Sc leads to stringent processing requirements and metastable device performance with no true understanding of how to achieve consistent, high-performance Sc contacts. In this work, WSe2 transistors with impressive subthreshold slope (109 mV dec(-1)) and I-ON/I-OFF (10(6)) are demonstrated without post-metallization processing by depositing Sc contacts in ultra-high vacuum (UHV) at room temperature (RT). The lowest electron Schottky barrier height (SBH) is achieved by mildly oxidizing the WSe2 in situ before metallization, which minimizes subsequent reactions between Sc and WSe2. Post metallization anneals in reducing environments (UHV, forming gas) degrade the I-ON/I-OFF by similar to 10(3) and increase the subthreshold slope by a factor of 10. X-ray photoelectron spectroscopy indicates the anneals increase the electron SBH by 0.4-0.5 eV and correspondingly convert 100% of the deposited Sc contacts to intermetallic or scandium oxide. Raman spectroscopy and scanning transmission electron microscopy highlight the highly exothermic reactions between Sc and WSe2, which consume at least one layer RT and at least three layers after the 400 degrees C anneals. The observed layer consumption necessitates multiple sacrificial WSe2 layers during fabrication. Scanning tunneling microscopy/spectroscopy elucidate the enhanced local density of states below the WSe2 Fermi level around individual Sc atoms in the WSe2 lattice, which directly connects the scandium selenide intermetallic with the unexpectedly large electron SBH. The interface chemistry and structural properties are correlated with Sc-WSe2 transistor and diode performance. The recommended combination of processing conditions and steps is provided to facilitate consistent Sc contacts to WSe2.

Structural, chemical and strain assessment of In-based quantum dots grown by a peculiar multistep MBE process, for application in intermediate band solar cells (IBSCs).

Deposition of Au nanoparticles (NPs) through UV ultra-short-pulse laser ablation in vacuum is a methodology suitable for obtaining high purity supported plasmonic NPs with a superb adherence to both planar and patterned substrates. Furthermore, the peculiarity that upon sub-picosecond laser irradiation NPs form directly within the target leads to narrow and controlled size-distribution. While extensive literature theoretically models phase changes and pressure relaxation of metal targets under sub-picosecond irradiation, the evolution of the nanostructured deposit through different ablation regimes is poorly documented experimentally. In this paper, besides modeling the temporal evolution of electron and lattice temperature following sub-picosecond laser pulse irradiation of Au bulk at the threshold ablation fluence (0.1 J/cm(2)), we report an accurate statistical, morphological and structural characterization of the AuNP distributions as a function of the laser fluence tuned from 0.1 to 3 J/cm(2) to drive the target through two ablation regimes. The occurrence of photomechanical spallation and phase explosion at low and high fluence, respectively, is correlated with the evolution of the NP deposits, which are discussed by providing a physical insight in the interplay between fluence-driven ablation regimes of the target, arrangement kinetics of the deposited species (NPs and vapour species) and (crystalline or amorphous) phase of the NPs. This knowledge is key for controlling the surface plasmon resonance response of AuNPs depending on the designed application.

The oxygen partial pressure during NiO deposition in reactive sputtering of a Ni target is used to control its carrier type and concentration, obtaining both nand p-type films. Carrier concentration can be controlled, ranging from 10(19) to 10(14) cm(-3). Films deposition is performed at 200 degrees C, a relatively low temperature that enables the use of glass as substrate. Experimental band diagrams for n-type NiO are obtained for the first time. Finally, a NiO homojunction is demonstrated by introducing a low carrier concentration layer in between n- and p(+)-type NiO layers. Layers are deposited in situ, preventing contamination and improving the interface quality, as observed by TEM. The Ni:O ratio for each layer was also obtained by analytical TEM measurements, demonstrating the impact of the oxygen partial pressure on the films' stoichiometry and the simplicity of our process to control carrier type and carrier concentration in oxide semiconductors.

N-polar InN layers were deposited using MOCVD on GaN-on-sapphire templates which were miscut 4° towards the GaN m-direction. For thin layers, quantum dot-like features were spontaneously formed to relieve the strain between the InN and GaN layers. As the thickness was increased, the dots elongated along the step direction before growing outward perpendicular to the step direction and coalescing to form a complete InN layer. XRD reciprocal space maps indicated that the InN films relaxed upon quantum dot formation after nominally 1 nm thick growth, resulting in 5–7 nm tall dots with diameters around 20–50 nm. For thicker layers above 10 nm, high electron mobilities of up to 706 cm2/V s were measured using Hall effect measurements indicating high quality layers.

Dy- and Tb-doped CeO2-Ni cermets for highly active solid-oxide fuel-cell (SOFC) anodes were fabricated by a one-pot electrodeposition process. Undoped, singly-doped, and co-doped powders were synthesized in an X-ray amorphous state, heat treated in air, and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) at different crystallization stages. In particular, in situ TEM analyses were carried out during heating in an oxygen atmosphere, in order to follow the evolution of structure and morphology and to understand the role of the dopants. The key structural effect of dopants was the inhibition of grain coarsening during heat treatment. Functional tests were carried out with micro-single chamber SOFCs, fed with a CH4/O2 mixture, the anodes of which were prepared with the CeO2-Ni powders synthesized in this study. A correlation was established between the electrocatalytic performance and the morphology of the anodic material, pinpointing that the finer and more homogeneous nanocrystalline structure of the doped powders results in better-defined and more active catalytic sites, thus improving the performance of the cell.

Aluminum nitride (AlN) thin films were deposited by sputtering on Ti bottom electrodes and integrated on a kapton substrate for flexible and stretchable electronics. The aim of this work was to find the best combination of Ti underlayer sputtering conditions and AlN over-growth to obtain the (002) nitride orientation, fundamental requirement for the piezoelectric response of the material in piezoelectric devices. Flexible electronics represent today’s cutting-edge electronic technologies thanks to their low cost and easy fabrication scalability.

Palladium has been widely employed as a hole contact to WSe2 and has enabled, at times, the highest WSe2 transistor performance. However, there are orders of magnitude variation across the literature in Pd-WSe2 contact resistance and I-ON/I-OFF ratios with no true understanding of how to consistently achieve high-performance contacts. In this work, WSe2 transistors with impressive I-ON/I-OFF ratios of 10(6) and Pd-WSe2 Schottky diodes with near-zero variability are demonstrated utilizing Ohmic-like Pd contacts through deliberate control of the interface chemistry. The increased concentration of a PdSex intermetallic is correlated with an Ohmic band alignment and concomitant defect passivation, which further reduces the contact resistance, variability, and barrier height inhomogeneity. The lowest contact resistance occurs when a 60 min post-metallization anneal at 400 degrees C in forming gas (FG) is performed. X-ray photoelectron spectroscopy indicates this FG anneal produces 3x the concentration of PdSex and an Ohmic band alignment, in contrast to that detected after annealing in ultrahigh vacuum, during which a 0.2 eV hole Schottky barrier forms. Raman spectroscopy and scanning transmission electron microscopy highlight the necessity of the fabrication step to achieve high-performance contacts as no PdSex forms, and WSe2 is unperturbed by room temperature Pd deposition. However, at least one WSe2 layer is consumed by the necessary interface reactions that form PdSex requiring strategic exploitation of a sacrificial WSe2 layer during device fabrication. The interface chemistry and structural properties are correlated with Pd-WSe2 diode and transistor performance, and the recommended processing steps are provided to enable reliable high-performance contact formation.

A novel biotechnological approach to the preparation of Ir-doped luminescent silica-based nanostructures is proposed availing use of diatoms microalgae which generate highly nanostructured biosilica shells (frustules) by in vivo biomineralization of orthosilicic acid. After the in vivo incorporation of a phosphorescent organometallic complex (Ir-1) in Thalassiosira weissflogii diatom frustules (DFs), bulk functionalized phosphorescent silica-based nanostructures are obtained by isolation and proper ultrafine processing of Ir-1-doped DFs. High-resolution characterization reveals the presence of phosphorescent hybrid organic/inorganic clusters composed of biogenic silica NPs intimately trapped within the diatom organic residual matter. The biofactory strategy investigated herein can be a sustainable, cost-effective, and scalable route to transition metal-doped silica nanomaterials and can pave the way to a great variety of heavy-metal and rare-earth metal doped silica nanostructures, whose applications range from photonics to imaging, sensing, and biomedicine.