Papers by Keyword: Optoelectronics

Abstract: TiO₂-based photocatalysis has attracted a lot of interest due to its potential to capture solar energy and drive important processes including the breakdown of pollutants and the development of sustainable energy sources. A series of magnesium, zinc, and cobalt nitrate nanocomposite samples with TiO₂ semiconductor nanocomposite samples have been successfully produced by employing a simple and very effective combustion technique with the oxidizing gas urea. Prepared pure TiO₂ nanoparticle was found to have a bandgap of 3.3 eV and a crystalline size of 57.8 nm. For Co, Mg, and Zn doped TiO₂, X-ray diffraction (XRD) studies show cubic, orthorhombic, and tetragonal crystalline structures with crystalline diameters ranging between 37 nm, 46 nm, and 87 nm. Optical study has demonstrated the absorbance, transmittance, and bandgap measurements of Co, Mg, and Zn doped TiO₂. The higher provider density brought on by the Brustein-Moss impact is responsible for the bandgap values' shift to higher energies, which vary from 4.43 eV to 5.35 eV. Visiblei light irradiation was used to measure the degradation of Rhodamine-B (RhB) dye; Co, Mg, and Zn doped TiO₂ explained high photocatalytic activity, which was thoroughly described. The addition of additional energy levels to the TiO₂ bandgap by the dopants results in a wider spectrum of light absorption and more effective use of solar radiation. Here reported the parameters affect how well TiO₂ nanoparticles infused with Mg, Zn, and Co perform photocatalysis.

Abstract: This study presents a novel contribution to the research of graphene-based electro-optic modulators. In this paper, we numerically demonstrate an ultra-compact and efficient graphene modulator based on metal-nanoribbon integrated hybrid plasmonic waveguide. Benefiting from the good in-plane mode polarization matching and strong hybrid surface plasmon polariton and grapheme interaction, the 10 μm-length modulator can achieve good modulation performance with a wide modulation bandwidth of 41.3 GHz and a low energy consumption of 101 fJ/bit at 1.55 μm. These compact and energy-efficient optical modulators may have broad application prospects in the future optical communication systems.

Abstract: Technological advancements and changing global needs drive deposition techniques, widely used for altering surface properties of components. The crosswinds from global technological advancements in the mobility and power sectors have piqued the interest in sustainable renewable energy tapping devices. Thin aluminium oxide (Al2O3) films are highly valued for various applications in the manufacturing industry, such as cutting tool coatings, optics, energy, and microelectronics. A novel and facile approach has been adopted in the present work to fabricate an oxide-based thin film on a BK7 glass substrate. The aluminium oxide film is deposited by reactive radio frequency (RF) magnetron sputtering by impinging adequate argon to oxygen ratio in a high vacuum environment. Furthermore, Al2O3 is deposited by an alumina target with the same deposition technique, and the results were compared. A digital thickness monitor (DTM) is used to assess the thickness of the deposited film for both processes. The films were first characterized by X-ray diffraction and then analysed by other characterization methods, including Scanning Electron Microscopy, Atomic Force Microscopy, Tribometer and Nanoindentation, and UV-visible spectroscopy. The results indicated that Al2O3 deposited by reactive RF magnetron sputtering performed better in terms of surface morphology, UV-absorbance, nanohardness, and wear resistance and is therefore, more reliable and sustainable when compared with non-reactive RF magnetron sputtering.

Abstract: Carbon Dots (CDs) have gained the attention of many researchers since its discovery in 2004 due to their unique nanostructure and properties. These are very promising carbonaceous nanomaterials having wide range of applications in sensors, imaging, energy storage, nanomedicine, electrocatalysis and optoelectronics. CDs have shown excellent physical and chemical properties like, high crystallization, good dispersibility and photoluminescence. Besides, these are now known to have excellent biocompatibility, long-term chemical stability, cost-effectiveness and negligible toxicity. Due to favourable physical structure and chemical characteristics, these nanocarbon-based materials have drawn an interest as supercapacitor (SC) electrode materials, opening upnew opportunities to increase the energy density and lifespan of SCs. Thus, variety of quick and affordable methods i.e., the arc-discharge method, microwave pyrolysis, hydrothermal method, and electrochemical synthesis have been developed to synthesize this versatile nanomaterial. There are undoubtedly many methods for creating CDs that are effective and affordable, but due to the safety and simplicity of synthesis, CDs made from waste or using environmentally friendly methods have been innovated. In order to devise sustainable chemical strategies for CDs, green synthetic methodologies based on "top-down" and "bottom-up" strategies have been prioritised. This review summarizes numerous synthetic strategies and studies that are essential for the creation of environment friendly processes for CDs. The recent developments in the use of CDs for photoluminescence and supercapacitance have been highlighted providing a clear understanding of the new source of energy and optoelectronic materials with a futuristic perspective.

Abstract: The article covers a solution of a modern electronics problem: improvement of data transmission device speed using the example of fiber-optic communication lines (FOCL). The data processing rate and throughput of transmission channels are determined by capabilities of the optoelectronics and, first of all, by the performance of its hardware components. The article presents all possible ways to improve the performance of FOCL. Design and production of communication devices moves to the nanotechnological level that opens up new possibilities for creation of semiconductors with advanced characteristics. The methods and means chosen for production of the nanostructures are crucial for creation of the new generation hardware components. Graphene is considered as the most promising material for creation of the new generation hardware components for semiconductors. Potential capabilities of the material are not yet fully explored. Isotopic nanoengineering is used as the method for production of the nanostructures with improved characteristics. In particular, we use the neutron transmutation doping technology based on irradiation of a graphite sample with a neutron flux. This method increases content of the ¹³C isotope (natural graphite contains only about 1.1% of this isotope). As a result, the band gap opens bringing the properties of the material closer to the properties of a semiconductor. The closer the width of the graphene band gap to the width of the silicon band gap, the closer the properties of graphene to the properties of semiconducting silicon. Furthermore, all properties of the natural graphite (high throughput and sensitivity to almost the entire optical spectrum) are preserved.

Abstract: Cu and Ni from CuNi metallic targets (composition 20-80 and 46-54 at.%) are deposited on Corning glass, quartz and the native oxide of Si (100) wafers by direct current magnetron sputtering in a high vacuum chamber (base pressure 5 x 10^-5 mbar). The CuNi films, with thickness 40 200 nm, are post annealed at temperatures 400 - 500 °C in a furnace under atmospheric air in order to be fully oxidized. The structure of the films is studied by x-ray diffraction experiments. Phase separation of the oxides is evident. The optical properties are studied via ultraviolet-visible light absorption spectroscopy. The spectra of CuNi-oxide films are compared with the spectra of the pure CuO and NiO films. Features originating from both CuO and NiO are detected in the spectra of the CuNi-oxide thin films.

Abstract: The spontaneous radiation energy of the current filaments in high gain GaAs photoconductive semiconductor switches (PCSS) is quantificationally analyzed. The spontaneous radiation formula of the current filaments was derived. The concept of the distribution function of the radiation intensity dependent on radiation wavelength was first introduced in GaAs samples. The radiative recombination coefficients of four peak wavelengths were estimated by the statistical-physical method in high gain GaAs PCSS. Calculated according to the radiative recombination coefficient of 890 nm radiation, the spontaneous radiation energies are consistent with the experimental observations. This explains the observations about optical output energy versus filament current.

Abstract: To explore the optic properties of transmission-mode GaAs photocathode module, experimental and theoretical values of reflectance and transmittance of photocathode module has been compared. it showns that experemental curves cannot tally with theoretical curves completely. The variation range of initial values of thickness is firstly setted. Modifing transmittance formula by a fitting coefficient A, optical properties is fitted using the method of error control. R-T combined error reduced from 15.2% to 4.9% using R-T combined error control scheme. Optimal fitting values of thickness of photocathode module are obtained, which are d₁ = 110 nm, d₂ = 1019 nm, d₃ = 1491 nm. And the error of total thickness is 2.9%.

Abstract: In the Current Study, the Structural Characteristics of Siox Thin Films Grown by Magnetron Sputtering on Si Substrates Are Reported. High Resolution Transmission Electron Microscopy Revealed the Formation of Amorphous Siox Films for the as-Deposited Samples, as Well as the Ones Annealed in Ambient Air for 30 Min at 950oC and of Si Nanocrystals, Embedded in Amorphous Siox, after Ar Annealing for 1-4 Hours at 1000oC. the Nanocrystals, with Sizes up to 6 Nm, Predominately Exhibit {111} Lattice Planes. Energy-Dispersive X-Ray Analysis Showed that the Si/O Ratio Is between 0.5-1, I.e. the Amorphous Films Comprise of a Mixture of Sio2 and Sio. Phase Images and Corresponding Strain Maps Created Using Fourier Filtering Revealed a Uniform Contrast in the Nanocrystals, which Shows that the Si Lattice Constant Does Not Vary Significantly. the Residual Strain Variations, around 4%, May Account for the Possible Existence of a Small Percentage of Highly Disordered Si or Siox Residual Clusters inside the Regular Si Matrix, in Full Agreement with Photoluminescence Measurements Performed on the same Materials.

Abstract: Thin Cu films of thickness 0.4 – 150 nm were deposited via radio frequency magnetron sputtering on Si(100) wafers, corning glass and quartz. Subsequently the Cu films were oxidized in ambient air at 230oC and 425oC in order to produce single-phase Cu2O and CuO, respectively. Selected samples were measured in the transmission geometry with the help of an ultraviolet – visible spectrophotometer. From the absorption spectra of the films, it was found that the gap EB for the dipole allowed transitions showed blue shifts of about 1.2 eV for the Cu2O thinnest film (0.75 nm), whereas the Edirect for the direct gap transitions showed blue shifts of about 0.16 eV for the CuO thinnest film (0.7 nm). The blue shift of the energy gap in the copper-oxide semiconductors is an indication of the presence of strong quantum confinement effects.