Deposition Technique Research Articles

Fabrication of solid-state plasmonic solar cell device using FTO|TiO2|Ag-nanoparticle assembly to generate hot electrons surpassing Schottky barrier

This work presents a detailed investigation into the fabrication and performance evaluation of plasmonic solar cells, where a thin film of silver nanoparticles is deposited onto a TiO₂ layer, with the silver film itself functioning as the active layer for light absorption and energy conversion. The study compares two deposition techniques—DC Magnetron Sputtering and Thermal Vapor Deposition (TVD)—revealing significant differences in the resulting device performance. The device fabricated using TVD demonstrated a significantly higher open circuit voltage of 440.3 mV and short circuit current density of 1.6 mA/cm² compared to the device fabricated via DC Magnetron Sputtering, which recorded an open circuit voltage of 56.92 mV and a short circuit current density of 0.03 mA/cm². These results indicate that TVD offers superior electron-hole separation, reduced recombination losses, and enhanced light absorption efficiency. The main contribution of this work lies in demonstrating that the TVD technique significantly improves the photovoltaic performance of plasmonic solar cells compared to DC Magnetron Sputtering. The study validates the hot-electron mechanism at the TiO2|Ag junction using Kelvin probe force microscopy, contributing valuable insights into the role of plasmonic effects in enhancing solar cell efficiency. Additionally, it underscores the potential of TVD for developing advanced solar cell technologies with higher energy conversion efficiency.

Ni/n-Si Schottky junction: Self-biased infrared photodetection via hot carrier photoemission

Internal photoemission-based hot electron generation at metal-semiconductor junctions holds significant potential for silicon-based sub-bandgap NIR photodetectors. In this work, we designed a simple nickel-silicon Schottky junction using the pulsed laser deposition technique and performed both experimental and theoretical analyses. To reduce the complexity of fabrication and lower costs, we used a planar nickel thin film on top of n-type silicon. The thickness of the nickel thin film was optimized to improve absorption and hot electron generation near the Ni/Si interface. We measured and calculated reflectance using the transfer matrix approach to quantify the effect of thickness on EQE. We also calculated the thickness-dependent absorption profile to estimate hot electron production near the junction. The current-voltage characterization of Ni/n-Si Schottky photodetector was investigated under the dark conditions as well under 1200 nm and 1300 nm light illumination. Under self-bias conditions, a photodiode with a 12 nm Ni thickness exhibits responsivity of 0.124 mA/W and 0.069 mA/W under illumination from 1200 nm and 1300 nm LED light, respectively. Furthermore, we used a comprehensive theoretical model to quantify the planar Ni/Si hot carrier generation and emission efficiency. and experimentally validated the calculated EQEs with the fabricated device. We believe the proposed complementary metal-oxide-semiconductor-compatible and simply structured Ni/Si Schottky photodetector will have potential applications in the silicon-based optoelectronics market.

Effects of Incorporating TiO2 Aggregates on the Growth, Anticorrosion, and Antibacterial Properties of Electrodeposited Multifunctional Coatings Based on Sn-Ni Materials

Multifunctional coatings based on Sn-Ni materials with and without titanium oxide nanoparticles (TiO2NPs) incorporation were prepared using the electrochemical deposition technique at 70 °C. TiO2NPs were dispersed in the electrolyte bath, and their influence on the surface texture, crystalline phase, and properties was investigated. Various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray microanalysis (EDX) were used to characterize the prepared coatings. The formation mechanism of the deposited coatings has been demonstrated to be consistent with the electrochemical behavior of instantaneous growth, and the three-dimensional growth is controlled by diffusion phenomena. The anticorrosion effectiveness of the coatings was assessed using potentiodynamic polarization curves and electrochemical impedance spectroscopy in an artificial sweat medium, while the bactericidal activity of the composite coatings (the ability to induce cell death) was evaluated in accordance with the ISO 27447:2019 test. The influence of TiO2NPs at a low concentration of 1 g/L on the composition, structure, and properties of the deposited coatings was demonstrated. Particular attention was paid to the relationship between the anticorrosive and bactericidal properties of the coatings and their structure composition and wetting properties. The synergistic effect of chemical composition and surface-wetting properties has been demonstrated to enhance the anticorrosive and bactericidal properties of the prepared coatings.

Solar Cells: Applications and Current Opinion

Due to the manufacturing process, silicon-based solar cells have conquered the marketplace, but their cost is not economic. As a result, thin-film manufacturing was done with low-cost, appealing materials generated using less expensive, scalable, and manufacturable procedures. The motivation behind this work is to develop low-cost, high-efficiency solar cells using chemical and electrochemical techniques. Thin film solar cell structure could be presented as glass, Cu structure, CdS window material, TCO, and CdTe absorber material. The absorber and window materials include layers such as CdS and CdTe, while Cu and TCO are the back and front contacts. By using CSS and chemical bath deposition (CBD), The usual method of making this structure is to grow window (CdS) and absorber (CdTe) materials. CBD is a batch method that generates enormous quantities of Cd-containing waste solutions each time, adding to the production process's high cost. Sputtering or PVD, including high vacuum conditions, is performed with back and front contacts. This research program focuses on developing an "all chemical-solar cell" structure. This study showed that CdS and CdTe materials may be employed and electrodeposited in thin-film solar cell systems, CBD and electroless techniques. Furthermore, the back and front contacts can be coated using the CdS electrolytic bath, which is utilized for seven months without being discarded, but the CBD bath lasts 2-3 days. The deposition rate of the thin films was about 50 - 100 times greater than reported values in the literature. The efficiency of the manufactured cells was between 1 and 6%, which was reduced by the duration of time. Twenty days after manufacturing a TCO, CdS, CdTe, the short-circuit current, Cu-Ag solar cell, and open-circuit voltage deposited by all chemical and electrochemical deposition techniques were 0.8 mA/cm2 and 8.8 mV, respectively. However, consistency and reproducibility remain unresolved. The growth of CdTe nanocrystalline thin film is one of the reasons it has been identified as having nanosized tracks. High-quality CdTe layers should be developed, or in cadmium solar cells, its layered structure is the form of a cadmium window and a zinc oxide buffer layer to increase the consistency of the solar cell efficiency.

Investigation on electronic and magnetic properties of Cr doped V2O5 thin films prepared by chemical solution deposition method

The present study examines the role of Cr doping on the electronic and magnetic behaviour of V2O5i.e. V2-xCrxO5 (x = 0, 0.05, and 0.10) thin films, prepared by chemical-solution deposition technique on Si (111) substrate. X-Ray diffraction technique shows the purity of the films and confirms no secondary phase formation. The atomic force microscopy was used to confirm the roughness of the films. A morphological investigation is done using High-resolution scanning electron microscopy associated with Energy dispersive X-Ray mapping of each element of the film. Fourier transform Infrared spectroscopy is utilised to identify functional groups that are present in obtained samples. The band-gap of these obtained samples is in the range of 0.8–0.6 eV, as examined by UV–Vis i.e., its value is decreasing with Cr doping. Using vibrating sample magnetometer, it is clear that samples shows ferromagnetic (FM) behaviour with saturation magnetization 0.3–0.6 μB/cc consistent with Langevin function fitting. It concludes the presence of FM behaviour of films and magnetization increases with carrier density, consistent with the carrier-induced origin of the ferromagnetism. X-ray photoemission spectroscopy (XPS) is utilised to understand its electronic properties. Core level spectra measurements suggest that V is in mixed state of 5+ and 4+. However Cr is in 3+ states. XPS and UV–Vis measurements imply that oxygen vacancies significantly contribute to the declination of the band gap and the promotion of FM-like behaviour. This discovery offers a promising pathway for engineering novel devices.

Correlation of Seebeck coefficient and selenization temperature in CuSe thin films grown on glass substrate

Copper selenide is emerging as a promising thermoelectric material that has the ability to harvest electricity from heat. In the present research work, copper selenide thin films were grown on glass substrate using thermal evaporation deposition technique. The phase transition from cubic to hexagonal structure was achieved by the selenization of grown samples at different temperatures (250, 300 and 350 °C) for 2 h. The phase, morphology and thermoelectric properties of the selenized CuSe thin films were studied using different characterization techniques. It was observed that the structural, morphological, and thermoelectric properties of the samples were modulated by varying the selenization temperature. XRD results suggested that as grown sample possessed a cubic phase but it transformed into hexagonal phase by selenization process. It was observed that Seebeck coefficient, electrical conductivity and power factor were modulated with the selenization temperature with maximum value of power factor (3.0 × 10−5±0.5 W m−1C−2) was obtained at optimal selinization temperature.

Optimization of deposition time on structural, morphological, and optical properties of Cd1-xZnxS nanocrystalline thin films

In this work, Cd1-xZnxS nanocrystalline thin films have been synthesized over a glass substrate by a simple and cost-effective Chemical Bath Deposition (CBD) technique at various deposition time keeping other deposition parameters constant. The structural, morphological, and optical properties are studied by incorporating a range of characterization techniques, including X-ray diffraction (XRD), Field Emission Scanning Electron Microscopes (FESEM), Energy Dispersive X-rays (EDX), and UV–Visible spectrophotometers (UV–Vis). The films have been deposited at five different deposition time in the range from 30 mins to 150 mins to record the changes which address in depth the structural, morphological and optical properties. Empirical fitting equations have also been developed to obtain a more quantitative analysis of the effect of deposition time. The results obtained in this work are compared with some recent reported works for performance analysis of the buffer layer. The proposed buffer layer deposited at 30 mins not only attains all the desirable qualities required for maximum extraction of solar energy but also a low-cost and environment friendly option, making it a potential candidate for solar cell and optoelectronic applications.

Fractal analyses of AlxGa1−xN thin film surfaces on AlN at different annealing temperatures

The determination of heteromorphological structures formed on the surface during annealing of AlxGa1−xN thin film grown on sapphire substrate using the metal organic chemical vapor deposition technique at different temperatures was investigated by fractal analysis method. The images of the surfaces of the thin films were taken by atomic force microscopy (AFM) at temperatures of 900, 1000, 1050 and 1200 °C respectively. AFM images were digitised in bitmap format according to the annealing temperatures. It was determined that the fractal dimensions obtained a linear correlation with the annealing temperatures. The results confirm the hypothesis that surface relaxation by the thermal action can produce fractal-like structures at particle or cluster boundaries. It is found that the observed cluster formation of superficial particles decreases as increasing temperature. The increase in temperature reduces the rate of superficial particle coating. To determine the surface roughness of the AlxGa1−xN thin film according to the annealing temperature, the AFM images were digitized in tagged image file format and the statistical root mean square, mean value, mean roughness, skewness and kurtosis values of the films were calculated. The roughness is a result of the thin film surface heteromorphology formed due to the specific annealing process. It is proved that the fractal dimensions of the AlxGa1−xN thin film increase as the annealing temperature rises. The particles coalesce on the surface and cluster in different types and sizes at each different annealing temperature, forming islets of different sizes. The skewness and kurtosis values show a different and irregular change.

Artificial synapses based on HfOx/TiOy memristor devices for neuromorphic applications

As a result of enormous progress in nanoscale electronics, interest in artificial intelligence (AI) supported systems has also increased greatly. These systems are typically designed to process computationally intensive data. Parallel processing neural network architectures are particularly noteworthy for their ability to process dense data at high speeds, making them suitable candidates for AI algorithms. Due to their ability to combine processing and memory functions in a single device, memristors offer a significant advantage over other electronic platforms in terms of area scaling efficiency and energy savings. In this study, single-layer and bilayer metal-oxide HfOxand TiOymemristor devices inspired by biological synapses were fabricated by pulsed laser and magnetron sputtering deposition techniques in high vacuum with different oxide thicknesses. The structural and electrical properties of the fabricated devices were analysed using x-ray reflectivity, x-ray photoelectron spectroscopy, and standard two-probe electrical characterization measurements. The stoichiometry and degree of oxidation of the elements in the oxide material for each thin film were determined. Moreover, the switching characteristics of the metal oxide upper layer in bilayer devices indicated its potential as a selective layer for synapse. The devices successfully maintained the previous conductivity values, and the conductivity increased after each pulse and reached its maximum value. Furthermore, the study successfully observed synaptic behaviours with long-term potentiation, long-term depression (LTD), paired-pulse facilitation, and spike-timing-dependent plasticity, showcasing potential of the devices for neuromorphic computing applications.

Fabrication and Characterization of Aluminum-Doped Nickel Oxide Thin Films for Optoelectronic Applications using the SILAR Method

Study’s Excerpt The effect of varying annealing times on 10% Aluminum-doped Nickel Oxide (ANO) thin films, deposited via the SILAR technique is presented. SEM and RBS analyses were used for detailed correlation between annealing time and the film's microstructural improvements. ANO thin films could be used for advanced technological applications. Full Abstract The effect of varying the annealing time of %10 aluminium-doped Nickel Oxide thin film was studied to understand the possible effect on the optical, structural, and electrical properties of %10 aluminium-doped Nickel Oxide (ANO) for possible application. The thin films were deposited on glass substrates using the successive ionic layer adsorption reaction (SILAR) deposition technique. The samples formed were annealed at 3000C, and the annealing time varied at 1.35 hrs., 1.45 hrs., 1.55 hrs., and 2 hrs, respectively. The deposited films were characterized to obtain the optical, electrical, and structural characteristics and the compositional constituent of the film using the double beam photo spectrometer, Four-Point Probe, Scanned electron Microscope, Energy Dispersion Spectroscopy, and X-ray Diffractometer. The films were observed to have low absorbance in the range of 0.1 to 0.01 and high % transmittance within the range of 80% - 98% in the visible region of the spectrum. The reflectance of the film was observed to decrease with an increase in annealing time in the range of 10% - 2.5%, all in the visible region of the spectrum. The crystallite size of the deposited films decreased with increased annealing time with the structural formation of simple cubic phase NiO thin film. SEM micrograph of the thin films reveals that an increase in annealing time improved the crystallinity of the films with the grain size evenly distributed. The EDS result of the deposited films revealed the presence of nickel, aluminum and Oxygen as the major constituent of the deposited films. The Ruther Ford Backscattering (RBS) analysis of the thickness of the films shows an increase in the thickness with an increase in annealing time. Clearer compositions of the films were also seen from the RBS analysis. Their electrical properties revealed that the films formed had low electrical resistivity and high conductivity, so they could be useful in making optoelectronics devices and corrosion resistance.

Effects of copper on hydroxyapatite thin films by pulsed laser deposition on silicon

AbstractThis study deals with the effect of Cu on hydroxyapatite (HAp) thin films on silicon substrates prepared by pulsed laser deposition (PLD) technique for Cu concentrations ranging from 0 to 0.8 wt.%. Fourier transform infrared spectroscopy and Raman spectroscopy provide additional evidence of HAp in the films, which exhibit characteristic HAp bands such as the 960 cm−1 phosphate ion band. The X‐ray diffraction patterns confirm the presence of HAp, without copper‐related peaks, suggesting that it is not incorporated into the HAp lattice, which is present as an amorphous phase. X‐ray photoelectron spectroscopy confirms the presence of Cu on the HAp thin films, possibly related to the adsorption of Cu2+ on HAp surfaces through electrostatic or interactions with (PO4)3− groups. Atomic force microscopy shows that the roughness of the films varies depending on the presence or absence of copper ions. Finally, density functional theory and kinetic Monte Carlo simulations explain the effects of atomic diffusion on roughness and HAp clustering. These changes correlate with the contact angle values, indicating the formation of hydrophobic films due to copper inclusions.

Neutron Radiation Effects on the Performance of the CdSe Thin Film for Photodetector Applications

Cadmium Selenide CdSe thin films were deposited on (7.5×1.3×0.1 cm3) glass substrates and (1×1 cm2) p-type silicon substrates using pulsed laser deposition technique (Nd: YAG laser beam with 80 mJ energy, λ = 1064 nm). Then, they were annealed at 300 °C for 1 h to get diodes as visible light detectors. Some of these samples (diodes) were exposed to different intervals (5, 7, 9, 12) days of neutron radiation using (241Am -10Be) source with a flux of 3×105 n/cm2.s and energy of 5.71 MeV. For comparison purposes, the other diodes were kept without any irradiation The morphological and electrical properties of these samples were studied by XRD, FE-SEM and I-V measurements. Results have shown all these thin films exhibit a hexagonal structure. However, there is a slight shift in the preferred orientation (100) for the irradiated films. Also, there was a new (102 - SiO2) peak that appeared in the irradiated thin film pattern. The crystallite size of pristine and (5, 7, 9, 12) days irradiated CdSe thin films were (26.9, 18.3, 24.9, 20.3 and 24.5) nm respectively, whereas, the mean particle size of the pristine film was 37 nm whereas for the irradiated films 53, 64, 73 and 92 nm. Results also show that the band gap of these samples increased from 2.17 eV for pristine thin films to 2.3, 2.48, 2.25, and 2.3 eV for the irradiated thin films. On the other hand, the results of I-V characteristics show the dark/light current. The current under illumination increases when exposed to small values of neutron radiation then it decreases with higher values of exposure. In contrast, the dark current decreases significantly with the irradiation. The effect of the irradiation was clear on the response/recovery period for all devices. Nevertheless, it was more profound in the response/recovery time of pristine devices. Also, the photo-responsivity of the pristine device was larger than the other devices and it was decreased with increasing absorbed doses. HIGHLIGHTS Hexagonal Structure: All CdSe thin films (both pristine and irradiated) exhibit a hexagonal structure, with a slight shift in orientation due to neutron irradiation. Neutron Radiation Impact: Neutron radiation causes a significant shift in crystallite size, decreasing the size for irradiated films. Additionally, a new (102 SiO2) peak emerges in irradiated samples, indicating radiation-induced changes. Band Gap Increase: The optical band gap of the CdSe films increased with neutron irradiation, starting from 2.17 eV in pristine films to values as high as 2.48 eV after irradiation. Morphological Changes: Irradiated films showed increased grain sizes, with neutron exposure leading to the enlargement of mean particle sizes from 37 nm in pristine samples to 92 nm in the most heavily irradiated samples. Electrical Behavior: Neutron irradiation impacted the photodetectors' electrical properties. The light current initially increased with small neutron doses but decreased with higher doses, while dark current consistently decreased after irradiation. GRAPHICAL ABSTRACT

(ZnO)1-x(SnO2)x/c-nSi gas sensors prepared by pulsed laser deposition technique for selective detection of nitrogen dioxide

(ZnO)1-x(SnO2)x/c-nSi gas sensors prepared by pulsed laser deposition technique for selective detection of nitrogen dioxide

Revolutionizing PET fabric performance with advanced metal deposition techniques

This study introduces an innovative approach to enhance both the air stability and conductivity of PET fabric using a novel dual-metal electroless deposition (ELD) technique. The fabric, woven with a combination of open weave (loose) and close weave (compact) designs, underwent coating with the metals nickel (Ni) and copper (Cu). Unlike conventional single-metal deposition methods, which often struggle to achieve optimal stability and conductivity simultaneously, this research pioneers the application of dual deposition to address these challenges effectively. The methodology entailed a series of carefully orchestrated steps including pretreatment, plasma treatment, silanization, polymerization, and ELD. The success of each stage was meticulously validated through water contact angle measurements, ensuring the efficacy of this work. Surface analysis techniques confirmed the uniform deposition of metals, as evidenced by surface morphology and elemental mapping. Additionally, detailed insights into the chemical composition and crystallinity of the coated fabrics were provided through XPS and XRD analyses. The results revealed a significant improvement in air stability and conductivity compared to traditional single-metal deposition methods. While fabrics coated solely with Cu exhibited high initial conductivity, they suffer from poor air stability. Conversely, Ni deposition demonstrated notable enhancements in air stability, with outcomes further influenced by the weave design of the fabric. Notably, in this work, the pioneering dual Ni-Cu deposition strategy not only addresses the air stability concerns associated with copper-coated fabrics but also maintains superior conductivity levels.

Design and Scalable Synthesis of Thermochromic VO2-Based Coatings for Energy-Saving Smart Windows with Exceptional Optical Performance.

We report strongly thermochromic YSZ/V0.855W0.018Sr0.127O2/SiO2 coatings, where YSZ is Y-stabilized ZrO2, prepared by using a scalable deposition technique on standard glass at a low substrate temperature of 320 °C and without any substrate bias voltage. The coatings exhibit a transition temperature of 22 °C with an integral luminous transmittance of 63.7% (low-temperature state) and 60.7% (high-temperature state) and a modulation of the solar energy transmittance of 11.2%. Such a combination of properties, together with the low deposition temperature, fulfills the requirements for large-scale implementation on building glass and has not been reported yet. Reactive high-power impulse magnetron sputtering with a pulsed O2 flow feedback control allows us to prepare crystalline W and Sr codoped VO2 of the correct stoichiometry. The W doping of VO2 decreases the transition temperature, while the Sr doping of VO2 increases the luminous transmittance significantly. A coating design utilizing second-order interference in two antireflection layers is used to maximize both the integral luminous transmittance and the modulation of the solar energy transmittance. A compact crystalline structure of the bottom YSZ antireflection layer further improves the VO2 crystallinity, while the top SiO2 antireflection layer provides also the mechanical and environmental protection for the V0.855W0.018Sr0.127O2 layer.

Angle‐Resolved Polarized Raman Study of Layered Cr2Se3

ABSTRACTThe polarization‐resolved Raman spectra of two‐dimensional Cr2Se3 synthesized via chemical vapor deposition (CVD) and chemical vapor transport (CVT) techniques were investigated in detail. The samples were characterized using X‐ray diffraction (XRD), transmission electron microscopy (TEM), and energy‐dispersive X‐ray spectroscopy (EDS). A distinct polarization dependence was observed in the Raman intensity of all the Cr‐Cr, Cr‐Se, and Se‐Se modes in both samples. The observed angle‐dependent Raman intensities of each peak could be related to the crystal structure‐specific Raman tensor. XRD results of the bulk Cr2Se3 sample synthesized via CVT confirm its trigonal crystal structure, and the Raman peaks can be fitted using the Raman tensors for the 𝐴𝑔 and 𝐸𝑔 modes for both the parallel and crossed polarizations. However, for the Cr2Se3 samples directly grown on Si/SiO2 substrates by CVD, it was necessary to assume the triclinic crystal structure in order to explain the polarized Raman dependence of all the peaks in both parallel and crossed polarization directions. This is the first experimental result suggesting the existence of triclinic Cr2Se3 crystal structure, which has been theoretically predicted in the Materials Project database.

Influence of Synthesis Parameters on Structure and Characteristics of the Graphene Grown Using PECVD on Sapphire Substrate.

The high surface area and transfer-less growth of graphene on dielectric materials is still a challenge in the production of novel sensing devices. We demonstrate a novel approach to graphene synthesis on a C-plane sapphire substrate, involving the microwave plasma-enhanced chemical vapor deposition (MW-PECVD) technique. The decomposition of methane, which is used as a precursor gas, is achieved without the need for remote plasma. Raman spectroscopy, atomic force microscopy and resistance characteristic measurements were performed to investigate the potential of graphene for use in sensing applications. We show that the thickness and quality of graphene film greatly depend on the CH4/H2 flow ratio, as well as on chamber pressure during the synthesis. By varying these parameters, the intensity ratio of Raman D and G bands of graphene varied between ~1 and ~4, while the 2D to G band intensity ratio was found to be 0.05-0.5. Boundary defects are the most prominent defect type in PECVD graphene, giving it a grainy texture. Despite this, the samples exhibited sheet resistance values as low as 1.87 kΩ/□. This reveals great potential for PECVD methods and could contribute toward efficient and straightforward graphene growth on various substrates.

Development of highly oriented crystals in the magnetoplumbite structure of metal (Sr, Cr, Sc) doped M-type BaFe12O19 hexaferrite films with improved optical and magnetic properties

We have deposited magnetoplumbite (P63/mmc) structured Ba-hexaferrite (BaFe12O19) and its metal (T: Sc and Cr) doped (Ba0.7Sr0.3Fe12O19 and BaFe11.5T0.5O19) films on Si substrate using the Pulsed Laser Deposition technique. The as-grown films showed preferential orientation of the crystals along (2 0 3), (2 0 7), (1 1 14), and (4 0 5) directions. The post-heat treatment oriented the crystals only along (2 0 7) direction. The Fe ions varied it charge state from +3 at the surface of the films to a mixed charge state in the interior, which promoted a local clustering of Fe3O4-like phase. Ferrimagnetic properties of the hexaferrite films have been modified due to metal doping. The bi-phased magnetic structure, arising from clustering of the soft ferrimagnetic Fe3O4 phase in the matrix of hard ferrimagnetic hexaferrite films, is suitable for tuning the magnetic coercivity and moment over a wide range of temperatures. The optical band gap in the range of 3.40–3.50 eV and a strong magneto-optical Kerr signal are promising for potential applications of the films in magneto-optical devices working in UV regime of radiation.

The investigation of endodontic irrigants and polyhexanide-based solution action on smear layer

AIM. The effect of irrigants on the smear layer on the intracanalicular dentin surface is one of the important issues in endodontics. The objective of this article is to determine the effect of different concentrations of polyhexanide-based solutions and standard irrigants on the smear layer using scanning electron microscopy (SEM).MATERIALS AND METHODS. The present study was conducted on 42 extracted teeth (third molars, first and second premolars) with formed apices that had been extracted for orthodontic indications. The teeth were decoronated and samples were prepared. In order to create a smear layer, the lumen of the canals was instrumented with H-file #40 throughout. A simulation of root canal irrigation was conducted by immersing the specimens in a 5-ml container filled with the proper solution for 1 hour: group 1 – no treatment (n = 6); group 2 – saline (n = 6); group 3 – 2% chlorhexidine (n = 6); group 4 – 3% sodium hypochlorite (n = 6); group 5 – 17% EDTA; group 6 – polyhexanide 0.1% (n = 6); group 7 – polyhexanide 0.2% (n = 6). A ~30 nm thick platinum film was sputtered onto the surface of each sample using a magnetron deposition technique. SEM microphotos were acquired on a Vega3 TESCAN scanning electron microscope (SEM) with an SE secondary electron detector, which enables imaging with high topographic contrast. The initial detector (incamera) was employed for image acquisition, with an electron energy of 30 keV. Images were acquired at magnifications of x20 (overview image), x150, x250, x500, x1000, x2500, x7500 for each sample.RESULTS. The samples from groups 1 and 5 demonstrated the absence of a smear layer on the dentin surface and the absence of smear plugs in the dentinal tubules. Groups 2 and 3 are distinguished by the deposition of a pronounced amorphous smear layer and the obturation of all dentinal tubules. Groups 4, 6, and 7 are distinguished by the deposition of a smaller volume of smear layer on the dentin surface, as well as the presence of semi-open or completely open entrances to the dentinal tubules.CONCLUSION. The data obtained indicates that antiseptic compositions based on polyhexanide in concentrations of 0.1 and 0.2% do not have a pronounced effect on the smear layer. However, in visual evaluation of SEM micrographs, their effect is comparable to that of 3% sodium hypochlorite. In instances where enhanced dissolution of the smear layer and smear plugs from the tubules is necessary to facilitate decontamination of the wall dentin, the combination of antiseptics with chelate compounds, such as 17% EDTA, may be employed.

Laser Control of Specular and Diffuse Reflectance of Thin Aluminum Film-Isolator-Metal Structures for Anti-Counterfeiting and Plasmonic Color Applications

Plasmonic structural color originates from the scattering and absorption of visible light by metallic nanostructures. Stacks consisting of thin, disordered semicontinuous metal films are attractive plasmonic color media, as they can be mass-produced using industry-proven physical vapor deposition techniques. These films are comprised of random nano-island structures of various sizes and shapes resonating at different wavelengths. When irradiated with short-pulse lasers, the nanostructures are locally restructured, and their optical response is altered in a spectrally selective manner. Therefore, various colors are obtained. We demonstrate the generation of structural plasmonic colors through femtosecond laser modification of a thin aluminum film–isolator–metal mirror (TAFIM) structure. Laser-induced structuring of TAFIM’s top aluminum film significantly alters the sample’s specular and diffuse reflectance depending on the fluence value and the number of times a region is scanned. A “negative image” effect is possible, where a dark field observation mode image is a negative of a bright field mode image. This effect is visible using an optical microscope, the naked eye, and a digital camera. The use of self-passivating aluminum results in a long-lasting, non-fading coloration effect. The reported technique could be used in anti-counterfeiting and security applications, as well as in plasmonic color printing and macroscopic and microscopic marking for personalized fine arts and aesthetic products such as jewelry.