Determination Of Band Gap Energy Research Articles

Advanced spectroscopic methods for probing in-gap defect states in amorphous SiNx for charge trap memory applications

Silicon nitride (SiNx) serves as the charge trap layer in current 3D NAND flash memory devices. The precise formation mechanism and electronic structure of localized defect trap states in SiNx remain elusive. Here, we present a refined experimental methodology to elucidate the in-gap defect states and the band gaps in amorphous SiNx thin films. Our approach integrates high-resolution reflection electron energy loss spectroscopy (REELS) and spectroscopic ellipsometry (SE) for comprehensive analysis. By systematical analysis, we aim to provide a robust method for determining in-gap electronic states in SiNx. We investigated two different SiNx films prepared by plasma-enhanced chemical vapor deposition and sputtering. Our analysis revealed several distinct in-gap states and determined band gap energies. This approach not only provide advanced spectroscopic methods to characterize the defect electronic states in SiNx, but also applicable to other large band gap semiconductors or dielectrics to predict device-level characteristics for future devices.

Sustainable synthesis of ZnO and FexOy nanoparticles and their nanocomposite ZnFe2O4: Comprehensive characterization and applications in antioxidant activity and antibiotics degradation efficiency

This study focuses on developing and evaluating eco-friendly nanoparticles, specifically FexOy NPs, ZnO NPs, and a ZnFe2O4 nanocomposite (NC), for potential applications in environmental remediation and biomedicine. The nanoparticles were synthesized and characterized using X-ray diffraction (XRD), which revealed their crystalline structures with sizes of 20.3 nm for FexOy NPs, 22.1 nm for ZnO NPs, and 10.9 nm for ZnFe2O4 NC. Fourier-transform infrared (FTIR) spectroscopy identified functional groups, while UV–visible spectroscopy determined band gap energies of 2.35 eV, 3.38 eV, and 2.68 eV for FexOy NPs, ZnO NPs, and ZnFe2O4 NC, respectively. Morphological analysis via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that FexOy NPs have cubic, hexagonal, and tetragonal forms, ZnO NPs are hexagonal nanorods, and ZnFe2O4 NC has a hexagonal-faced cubic structure. Antioxidant activity, assessed through the DPPH assay, revealed that ZnFe2O4 NC had the highest potency. Additionally, under sunlight irradiation, ZnFe2O4 NC demonstrated superior degradation of the antibiotic cephalexin (96 % within 30 min) compared to FexOy NPs (58.2 %) and ZnO NPs (52 %), with respective kinetic rate constants of 0.109 min−1, 0.029 min−1, and 0.025 min−1. These results highlight the nanoparticles’ potential for environmental and biomedical applications.

Fast Fourier Transform Implementation for Determining Band Gap Energy from UV–Vis Spectra as a Fresh Methodology

Fast Fourier Transform Implementation for Determining Band Gap Energy from UV–Vis Spectra as a Fresh Methodology

Sustainable Sol‐Gel Approach for Visible Light‐Responsive Titanium Dioxide Nanoparticles in Efficient Diazinon Removal

AbstractThis study addresses water pollution challenges by employing photocatalysis as an effective solution. Titanium dioxide (TiO2) with unique characteristics is widely utilized in this approach. However, the design of nanosized TiO2 particles is crucial for enhancing photocatalytic performance during diazinon's photodegradation. As such, the TiO2 nanoparticles (NPs) were synthesized via the green sol‐gel method in this study, exhibit a mixed anatase‐brookite phase, a small particle size of 11.17 nm, and lower bandgap energy (3.00 eV) than pure anatase TiO2 of 3.20 eV, rendering them active under visible light. DFTB calculation was deployed to investigate the role of oxygen vacancies in reducing the bandgap energy. Experimentally measured (3.00 eV) and computationally (2.812 eV) determined bandgap energies align well. The TiO2 NPs demonstrate significant photocatalytic efficacy, degrading 73.3 % of diazinon within 210 min under sunlight, with a mineralization degree of 43.50 %, and 2‐isopropyl‐6‐methylpyrimidin‐4‐ol (IMP) was detected as the intermediate product. The photodegradation follows first‐order kinetics, and adsorption isotherm analysis fits the Langmuir model. ⋅O2− is identified as the predominant reactive oxygen species in the diazinon's photodegradation. Hence, the synthesized TiO2 NPs offer good reusability, maintaining a degradation efficiency of 67.4 % even after five cycles, showing good potential for wastewater treatment applications.

Green Synthesis of Cu<sub>2</sub>O Nanoparticles and Their Application for the Photodegradation of Methyl Orange in Aqueous Media

The existence of colorants in water has caused many disadvantages to aquatic systems and the environment. Scientists have made efforts to decompose and remove them using many different methods. In this study, Cu2O nanoparticles were synthesized with a mixture of reducing agents, including glucose and ascorbic acid, as a photocatalyst for decomposing azo dyes. The prepared nano Cu2O was fully characterized using scanning electron microscope (SEM) imaging, X-ray diffraction (XRD) diffraction measurements, and band gap energy determination. The obtained nano Cu2O was of a uniform truncated block shape with particle size ranging from 50 to 150 nm. The prepared nano Cu2O showed remarkable photocatalytic behavior toward methyl orange under visible light radiation with the removal percentage of 95.46% after 4 hours of reaction. In addition, the catalyst can be reused many times without much impact on catalytic efficiency. Photocatalytic degradation using Cu2O nanoparticles is a promising method for the removal of methyl orange, contributing to creating a safe and sustainable environment.

Fe3O4-CdO Nanocomposite for Organic Dye Photocatalytic Degradation: Synthesis and Characterization

In this study, pure CdO nanoparticles, magnetic Fe3O4 nanoparticles, and Fe3O4-CdO nanocomposites were prepared via a solution combustion method using cetyltrimethylammonium bromide (CTAB) as a template. These prepared nanomaterial samples were characterized by X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron microscopy (XPS), transmittance electron microscopy (TEM), and scanning electron microscopy (SEM) analysis. XRD patterns confirmed the purity and the crystalline nature of the prepared samples. FTIR and Raman spectra observed the metal-oxygen (M-O) bond formation. UV-vis DRS studies were performed to investigate the optical properties and the bandgap energy determination. The surface morphology and the size of the pure CdO nanoparticles, magnetic Fe3O4, and nanocomposites of Fe3O4-CdO were determined via TEM and SEM analysis. Under optimum experimental conditions, the Fe3O4-CdO nanocomposites were applied for photocatalytic activity against Methylene blue dye. Under visible light irradiation, Fe3O4-CdO nanostructures showed an efficient photocatalytic degradation of 92% against Methylene blue organic dye and showed excellent stability for multiple cycles of reuse.

Cotton fabric loaded with ZnO nanoflowers as a photocatalytic reactor with promising antibacterial activity against pathogenic E. coli

Nanofinishing is the process by which ultrafine dispersion of nanomaterials is applied to a textile for the development of functionalities. The utilization of nanometal oxides as antimicrobial agents have shown a substantial antimicrobial property in cotton. In the present study, previously synthesized powder containing ZnO nanoflowers (ZnO NFs) was characterized for morphology, surface composition, roughness, and charge using Transmission electron microscopy (TEM), Scanning transmission electron microscopy (STEM), Atomic force microscopy(AFM) and Zeta potential. Optical properties of crystalline ZnO were determined by Photoluminescence (PL), Diffused reflectance Spectroscopy (DRS), and bandgap energy determination. Highly crystalline, ZnO NFs bearing crystal defects and high surface charge were loaded onto the pristine cotton by a dip coating method using Triton X-100 as dispersant and iSys MTX fabric binder. The pristine cotton fabric of 125 g/m2 was nano finished by loading 20,42 and 58 µg/cm2 (1–3 dip cycles) ZnO NFs respectively. The loading of ZnO NFs onto the surface of cotton fabric was confirmed by SEM and used for antibacterial activity against E. coli as a photocatalytic reactor. The prepared samples were irradiated with a UV lamp of λmax = 254 nm (15 min, 30 min, 45 min) and D65 artificial sunlight (60 min, 120 min, 180 min) to investigate their photocatalytic activity against pathogenic E. coli using modified Breed Smear’s method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ZnO NFs@ cotton were determined as 19.53 µg/ml and 39.06 µg/ml respectively after exposure to UV light. After exposure to sunlight MIC and MBC observed were higher i.e. 156.25 µg/ml and 312.5 µg/ml respectively showing lesser activity in sunlight as compared to ionizing UV radiations. To verify the photocatalytic activity, hydroxyl radicals generated by ZnO NFs@ cotton were also determinedtime-resolved PL on exposure to a UV lamp and D65 artificial sunlight. This nano-finished cotton is a promising candidate to be used as a medical textile with high antibacterial activity even after 20 washing cycles with only a 5% decrease in efficiency.

Efficacious elimination of crystal violet pollutant via photo-Fenton process based on Gd(2−x)La(x)Zr2O7 nanoparticles

The photo-Fenton process is an appropriate method of the Advanced Oxidation Process that is used in the photocatalysis of organic dyes like crystal violet (CV). La3+ ion substituted gadolinium zirconium oxide Gd(2−x)La(x)Zr2O7 nanopowders (x = 0.1, 0.2, 0.3, and 0.5) have been successfully prepared by using sol–gel auto-combustion method to be used for the efficient photocatalysis of CV with photo-Fenton process. The well-crystallized defect-fluorite, structured with space group: Fm-3m, was detected using X-ray diffraction analysis. The lattice parameters were found to increase with the evaluated La3+ ion concentration. The grain size of the synthesized powders increased with the increase in La3+ ion content. The SAED patterns depicted fluorite structured fluorite. UV/Vis. spectrophotometer was used for the determination of band gap energy of Gd(2−x)La(x)Zr2O7 nanopowders which increased with increasing La3+ ion content. It was found to enhance from 4 to 3.6 eV. The visible spectrophotometer was used for determining unknown concentrations during the photocatalysis process to assure the effectiveness of the process. Overall, results illustrate that the photo-Fenton reaction on Gd(2−x)La(x)Zr2O7 performed excellently in removing crystal violet (CV). The photo-remediation ratio of CV reached 90% within 1 h.

Spatially Resolved Optical Spectroscopic Measurements with Simultaneous Photoelectrochemical Mapping Using Scanning Electrochemical Probe Microscopy

A deep understanding of the properties of semiconductor films at the micro-/nanoscale level is fundamental toward designing effective photoelectrocatalysts. Here, we integrated spatially resolved optical spectroscopy (SR-OS) with scanning photoelectrochemical microscopy (SPECM) to collect UV/vis spectra and quantify photocurrents of localized sites on a nanostructured BiVO4 thin film. Direct measurement of absorbance allowed for the determination of band gap energy at each location. Absorbance and photocurrent maps were obtained and used to investigate heterogeneities on the films. Scanning electrochemical cell microscopy (SECCM) was also coupled with SR-OS to acquire quantitative photoelectrochemical data at the FTO/BiVO4 film interface, revealing higher photocurrents at the boundary regions. As a droplet-based technique, SECCM was employed to estimate the wetted area by measuring the maximum height of droplet stretch at each point, allowing for the calculation of photocurrent density. This novel approach provides an advantageous mean to correlate localized photocatalytic activities and band gap energies.

Glass tube-coated TiO2 nanostructure for degradation of methylene blue: an experimental and design of column photocatalytic reactor

This work presents the successfully of TiO2 nanostructure synthesis using manual grinding combined hydrothermal method for photocatalyst. XRD confirmed that TiO2 was arranged by anatase and rutile phase with crystal size of 18.54 nm. Characterization of digital microscope shows the spread of catalyst on the glass tube surface, which can be observed furthermore using interactive 3D surface plot. Band gap energy determination from UV-Vis spectroscopy scanning shows the minimum energy that is required to facilitate electron-hole generated. In 20 min of irradiation, TiO2 existence can completely decompose MB (100%) that can be presented by TiO2 absence. Degradation of MB is higher effective in acidic condition which optimum pH of 5. Using first order reaction, glass tube-coated TiO2 has rate constant of 0.2102 min-1, 1.5 times faster than bare glass tube. This enhancement proves that the designed reactor has good prospect for organic pollutant treatment. Moreover, compared with other reported study, this system provides relatively more effective of MB photodegradation.

Opto-electronic, crystallographic, and Judd-Ofelt analysis of novel gadolinium-based europium doped BaSrGd4O8 nanophosphor for advanced pc-WLEDs

• Red-light emanating BaSrGd 4 O 8 :Eu 3+ nanocrystals have been prepared for first time via urea assisted solution combustion approach. • The detailed structural and photoluminescence analysis are done effectively. • SEM, TEM, EDAX, and TGA characterizations are done to explore morphological aspects, elemental analysis and thermal stability. • Kubelka-Munk hypothesis has been utilized to determine band-gap energy using DR spectra. • Significant utilization in various photonic and solid-state lighting applications. A sequence of novel BaSrGd 4 O 8 :Eu 3+ nanophosphor was fabricated with the aid of solution combustion (SC) methodology. Phase formed and morphological attributes were examined by PXRD, SEM, and TEM techniques. Rietveld refinement confirmed the Space group Pnma (62) and Orthorhombic phase. Diffuse reflectance, decay curves, and photoluminescence spectra were utilized to look into the photoluminescent features. Exclusive red emission was observed due to the 5 D 0 → 7 F 2 transition with optimal composition found at 15.0 mol %. The decay lifetime and quantum efficiency for the optimized nanophosphor were found to be 1.5495 ms and 72.5 %. Energy band gap values for the host matrix as well as optimized sample were also calculated that were found to be 5.27 and 3.46 eV respectively. CIE and CCT coordinates confirmed an efficient red emission that enhances its application vision in optical appliances.

Green biosynthesis of Fe3O4 nanoparticles using Chlorella vulgaris extract for enhancing degradation of 2,4 dinitrophenol

ObjectivesThis study aimed to provide the excellent role of Chlorella vulgaris extract as a green, reducing agent for improving and enhancing the effectiveness and performance of as-prepared NPs, which is higher than bare Fe3O4. MethodsThe extract of the algal cell of Chlorella vulgaris is used as a green, reducing agent was used to prepare green Fe3O4 NPs to improve and enhance the degradation effectiveness of 2,4 dinitrophenol (2,4 DNP) in their aqueous solution using UV irradiation. The as-synthesized bare Fe3O4 and green Fe3O4 NPs were characterized using UV–VIS spectroscopy, TEM, SEM, EDX, XRD, and FT-IR spectroscopy to determine bandgap energy, particle size, structural morphology, crystallite nature, phase structure, elemental compositions, and existed functional group. ResultsSEM and TEM images indicated that the as-synthesized NPs have a regular spherical shape with a mean size ranging between 13.68 and 31.71 nm. The energy bandgap (Eg) indicated the green Fe3O4 NPs have low values (2.73 and 2.3 eV) than bare Fe3O4 (2.89 eV). The maximum degradation of 2,4 DNP was achieved at pH = 8, 90 min contact time, 0.35 g/L catalyst dose, and 100 mg/L 2,4 DNP concentration. ConclusionThe degradation results proved that green Fe3O4 NPs have more effectiveness than bare Fe3O4 NPs.

Determination of Band Gap Energy of ZnO/Au Nanoparticles Resulting in Laser Ablation in Liquid

The synthesis of ZnO and ZnO/Au nanoparticles using the laser ablation method in liquid has been successfully carried out. Characterizing the optical properties of ZnO and ZnO/Au using a UV-Vis Spectrophotometer (Ocean Optic MAYA Pro 2000) measured in the wavelength range of 275-875 nm. The characterization results obtained are absorbance and band gap values of ZnO and ZnO/Au nanoparticles. This study found the absorbance values of ZnO nanoparticles at wavelengths 330 and 335 nm. After obtaining the absorbance value, the band gap value was analyzed for ZnO and ZnO/Au nanoparticles, respectively, 3.23 eV and 3.17 eV. The decrease in the band gap value in ZnO is due to the presence of Au in ZnO nanoparticles which can replace one of the lattices in the ZnO crystal structure.

Influence Of Co Doping On Structural And Band Gap Energy Properties Of ZnO Based Varistor Ceramic

Photopyroelectric (PPE) technique has been widely used in applied science and technology fields including the study of materials in thermal and optical properties. The sample, Zn1-xCox (x= 0.4, 0.8, 1.2, 1.6, 2.0 wt%) was prepared using solid state method sintered at 1200 ͦC to study the effect of concentration on the energy band gap (Eg). XRD, SEM with EDX analysis were used to characterise the materials' structure, morphology, and density. The PPE setup is used to determine band gap energy (Eg) values. The Eg shows the decreasing trend when the concentration of CoO increases

Dispensability of the conventional Tauc’s plot for accurate bandgap determination from UV–vis optical diffuse reflectance data

The use of the conventional Tauc’s method to determine optical bandgap energy from UV–vis spectroscopy data has been overemphasized for decades. However, a misuse of the Tauc’s formula in conjunction with the Kubelka-Munk function to determine the bandgap energy of semiconductors from diffuse reflectance data can lead to erroneous estimates. Particularly, large errors can be associated with computing values of the ordinate using the Tauc-Kubelka-Munk relationship for diffuse reflectance to produce Tauc’s plot. To address this apparent error, the present paper shows that the reflectance versus photon energy plot for bandgap estimation from UV–vis diffuse reflectance data can be employed to obtain reasonable bandgap values, suggesting that the conventional Tauc’s plot is not indispensable for accurate bandgap energy determination. The relatively simple method can be best choice when a researcher is unsure about the accurate computations from diffuse reflectance data which lead to proper Tauc’s plot. Interestingly, the rarely reported (if at all it can be found elsewhere) step-by-step approach to Tauc’s plot from diffuse reflectance data is described in this paper to serve as a simple guide for emerging material scientists. The UV–vis optical diffuse reflectance data for β-Ga2O3, ZnO and TiO2 semiconductor films are used for this study.

An Investigative Study on the effect of Dopants on Manganese Based Mixed Nano Ferrites Synthesized through Sol-Gel Method

The present article investigates the effect of different dopants on manganese based mixed nano ferrites synthesized through sol-gel method.MnF, MnCoF and MnCoMgF (MnFe2O4, Mn0.5Co0.5Fe2O4andMn0.5Co0.25Mg0.25Fe2O4) were synthesized by Sol-gel method. The structural, magnetic and optical properties of the samples were analysed through XRD(X-RayDiffractometer), VSM (Vibrating Sample Magnetometer,) and UV-Visible Spectroscopy. The phase identification and lattice parameter determination were carried out by using X-RayDiffraction and hence the crystallite size and X-Ray density were calculated. Peaks (220), (311), (400), (511), and (440) were obtained from the XRDpattern of the samples, which confirmed their single-phase cubic spinel structure. It was observed that because of the large ionic radius of Co2+ (0.745 Å) ions as compared to that of Fe3+ (0.645 Å) ions, lattice parameter of MnCoF increased in comparison with that of MnF but, the substitution of Mg2+ to MnCoF sample decreased the lattice constant. By investigating the hysteresis loops produced by the samples in the VSM analyses, it was found that the MnF have low coercivity and moderate saturation magnetization amongst the three. The substitution of Mg2+ in MnCoF sample decreased the value of saturation magnetization. UV-Visible analysis was used to determine bandgap energy of three samples.From the Tauc plot, we can observe bandgap energies of 3.202 eV, 3.180 eV and 3.239 eV, for MnF, MnCoF and MnCoMgF respectively.On substituting with the Co2+ in MnF the band gap of sample decreases indicating quantum confinement phenomenon.When substitution was done both Co2+ and Mg2+, the band gap energy value increases.

Bandgap energy model for GaInNAsSb/GaAs alloys with high N content and strain influence

Bandgap energy of dilute nitride GaInNAsSb/GaAs alloys with N compositions as high as 8% are estimated using a method based on band anti-crossing model used for GaNAs/GaNSb/InNAs/InNSb ternary compounds. The parametrization of the model is defined by fitting with experimental composition and bandgap energy values employing a differential evolution algorithm. The effects of lattice strain on the bandgap energy are taken into account by the model resulting in an accurate prediction of the bandgap energy with an average deviation of only 12 meV compared to the experimental data. The model provides a useful tool for accurate determination of bandgap energies of dilute nitrides, including narrow bandgap, i.e. ∼0.7 eV GaInNAsSb alloys, which are becoming increasingly relevant in the development of high-efficiency lattice-matched multijunction solar cells.

PHOTOCATALYTIC OPTIMIZATION OF MR DYE BY K-ZnO AND ZnO CATALYSTS UNDER VISIBLE IRRADIATION

The lucubration on the visible light methyl red (MR) degradation using K-ZnO and undoped ZnO photo catalyst was investigated. The successive formation of K-ZnO was ascertained by several techniques such as scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and UV-Visible spectrophotometer and solid state UV-Vis band gap energy determination by comparing the Kubelka-Monk equation with Tauc equation and the energy band gap was calculated to be 3.28ev. The influence of reaction variables such as MR concentration, reaction pH, catalyst loadings and temperature have been investigated for both process. The kinetics model was developed for both doped and undoped ZnO photocatalyst using pseudo first and second order kinetics, the result indicated that both doped and undoped ZnO followed pseudo first order kinetics due to higher correlation coefficient (R2) value of 0.985 and 0.922 with rate constant (k) of 0.026 min-1 and 0.062 min-1, respectively. Based on the rate constant value (k) obtained at different reaction temperatures, the Arrhenius expression was derived. The derived activation energy (Ea) for the degradation of MR by K-ZnO photocatalysis was 32.109x103JK-1. The optimum condition for K-ZnO showed nearly complete degradation (95%) of the dye molecules with slightly higher degradation efficiency compares to ZnO (91%).

Molybdenum carbide doped with nanostructured nickel for application in degradation of reactive dyes

Abstract Carbide-type ceramic materials such as nickel-doped molybdenum carbide have promising photocatalytic degradation activity. The addition of nickel to the molybdenum carbide aims to increase its reaction yield and also its characteristics. The objective of this paper was to study the photocatalytic activity of Mo2C and 5% and 10% nickel-doped Mo2C materials used for the degradation of the Maxilon Blue GRL 300 textile dye. The structural properties were characterized by X-ray diffraction and scanning electron microscopy. For the determination of band gap energy, diffuse reflectance spectroscopy was used. The samples of the photocatalysis tests were analyzed by UV-visible spectroscopy. The best reaction yield was observed for the 5% nickel-doped molybdenum carbide sample in photocatalytic tests, reaching a yield of around 92% in the final concentration of the dye solution.

Comparative Study of Nanostructured CuSe Semiconductor Synthesized in a Planetary and Vibratory Mill.

Copper(II) selenide, CuSe was prepared from Cu and Se powders in a stoichiometric ratio by a rapid, and convenient one-step mechanochemical synthesis, after 5 and 10 min of milling in a planetary, and an industrial vibratory, mill. The kinetics of the synthesis, and the structural, morphological, optical, and electrical properties of CuSe products prepared in the two types of mill were studied. Their crystal structure, physical properties, and morphology were characterized by X-ray diffraction, specific surface area measurements, particle size distribution, scanning, and transmission electron microscopy. The products crystallized in a hexagonal crystal structure. However, a small amount of orthorhombic phase was also identified. The scanning electron microscopy revealed that both products consist of agglomerated particles of irregular shape, forming clusters with a size ~50 μm. Transmission electron microscopy proved the nanocrystalline character of the CuSe particles. The optical properties were studied using UV–Vis and photoluminescence spectroscopy. The determined band gap energies of 1.6 and 1.8 eV for the planetary- and vibratory-milled product, respectively, were blue-shifted relative to the bulk CuSe. CuSe prepared in the vibratory mill had lower resistivity and higher conductivity, which corresponds to its larger crystallite size in comparison with CuSe prepared in the planetary mill.