Optical Properties Of ZnO Research Articles

Correlation Between Structural, Electrical, and Optical Properties of ZnO:In for Ethanol Gas Sensing Application

Correlation Between Structural, Electrical, and Optical Properties of ZnO:In for Ethanol Gas Sensing Application

First-principle calculation of the electronic structure and optical properties of ZnO and Al:ZnO

First-principle calculation of the electronic structure and optical properties of ZnO and Al:ZnO

A combined theoretical and experimental study on vertically aligned ZnO and ZnO: Sn

Vertically aligned ZnO and Sn (5, 10 v/v%) doped ZnO microrods were produced using chemical bath deposition technique on ZnO seed layers fabricated on glass substrates by spin coating method. The thickness of the seed layer is 365 nm and the length of the ZnO and ZnO:Sn rods are in the range of 1–5 μm. The length of the rods decreases with increasing Sn concentration. The structural, morphological, elemental compound, electrical and optical properties of ZnO and ZnO:Sn films were investigated using x-ray powder diffraction, field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, two probe method and UV–Vis absorption spectroscopy, respectively. The electronic structure of ZnO and Sn doped ZnO is calculated depending Density Functional Theory thanks to the WIEN2k program. Based on experimental and theoretical calculations, the band gap energy decreases with increasing Sn concentration. The band gap energy of seed layer, pure ZnO, Sn (5%) and Sn (10%) doped ZnO films was estimated as 3.27 eV, 3.18 eV, 3.14 eV and 3.12 eV, respectively. The band gap energy of Sn (1 atom) and Sn (2 atom) doped ZnO calculated theoretically was found as 0.392 eV and 0.245 eV, respectively. The Fermi Energy shifting towards the conduction band was observed upon Sn doping. Sn (5%) doped ZnO film shows the highest electrical conductivity although its band gap energy is higher than that of Sn (10%). The highest conductivity is attributed to the lowest dislocation density and less oxygen vacancies in the structure.

Effect of Substrate Temperature and Deposition Power on the Surface Morphology and Optical Properties of ZnO:Mg Thin Films Deposited by DC Magnetron Sputtering

Magnesium doped zinc oxide (ZnO:Mg) thin films were deposited on soda lime glass slides by DC magnetron sputtering method. Atomic force microscope (AFM), and UV/VIS spectrophotometer were used to investigate the effect of sputtering power and substrate temperature on the surface morphology and optical properties of ZnO:Mg thin films. AFM images revealed that sputtering power and deposition temperature have significant influence on surface morphology of the ZnO:Mg thin films. For all sputtering powers and substrate temperatures investigated, ZnO:Mg films had peak transmittance above 85%. Samples deposited at 110 W sputtering power and 450 °C substrate temperature showed the best peak transmittance of > 90% at 560 nm (visible range). Optical band gap of ZnO:Mg films was in the range of 3.44– 3.69 eV depending on the substrate temperature. The results indicated the potential of the films for transparent conductor applications.

Structure, electrical and optical properties of ZnO and Cu-doped ZnO films prepared by magnetron sputtering at different H2 fluxes

Structure, electrical and optical properties of ZnO and Cu-doped ZnO films prepared by magnetron sputtering at different H2 fluxes

The interface structural, electronic and optical properties of ZnO nanowires/Graphene nanohybrid (ZnO NWs/G): Experimental and theoretical DFT investigations

In this work, a ZnO nanowires/graphene nanohybrid was synthesized by a three steps approach. Copper substrates were covered with graphene by chemical vapor deposition, further ZnO nanowires were electrochemically deposited on the as grown graphene on copper and finally a transfer process was employed for moving the heterostructure onto a different substrate. A comprehensive structural analysis which included scanning electron microscopy, X-ray diffraction and Raman measurements revealed that the ZnO nanowires crystallize in wurtzite structure perpendicular to graphene, the process leading to the formation of a nanohybrid heterostructure. The band gap energy of the ZnO nanowires deposited on graphene was estimated to be 3.11 eV, as calculated from the reflectance spectrum analysis. The GGA-PBE+U within Grimme (DFT-D) approach was used to provide an accurate description of the interface structure in terms of electronic and optical properties, confirming that the decrease in the band gap energy of ZnO nanowires is caused by the interaction with the graphene surface. The findings of this study could serve as an experimental and theoretical reference for upcoming studies on ZnO NWs/Graphene nanohybrid-based optoelectronic applications.

Effect of Co doping of (Ga, In) and 2N preferred orientation on the magnetic and optical properties of ZnO

Current research on the Zn1−xMxO1−yNy (M = Ga, In) system mainly focuses on the p-type property, where Ga–N or In–N has different preferred orientations for bonding. Studies on the magnetic, bandgap, and optical properties of ZnO co doped with N are also lacking. The generalized gradient approximation (GGA+U) plane wave ultrasoft pseudopotential method based on density functional theory is used to systematically investigate the effects of the magnetic, band gap, and optical properties of the system for addressing the aforementioned problems. Results show that the formation energy of the Zn1−xMxO1−yNy (M = Ga, In) system is negative, all doping is easy, and all doped systems are stable and magnetic. The magnetism comes from the double exchange effect of electron spin polarization. Research has found that the band gap in Ga–N or In–N bonding along the c-axis direction is narrower than that along the a-axis direction. In the low-energy region, the redshift of the absorption spectrum is more significant, and the absorption or reflection coefficient and the carrier polarization and activity are stronger. In particular, In–N forms bonds along the c-axis direction and is co doped with another N in ZnO, which results in the narrowest band gap and the most significant redshift in the absorption spectrum. The absorption of sunlight can also be achieved in the ultraviolet visible near-infrared region. The absorption or reflection coefficient and the carrier polarization and activity are relatively strongest. This work has certain reference value for the design and preparation of new solar cell light absorbing materials based on ZnO.

Microwave-Assisted Biosynthesis of ZnO Using Sentul <i>(Sandoricum koetjape) </i>Peel Extract: Effect of Microwave Irradiation Power

Physical and chemical approaches for synthesizing ZnO have disadvantages, such as requiring high temperatures, expensive equipment, and dangerous substances. Preparation of ZnO nanoparticles has shifted its focus to the biosynthesis technique involving plant extracts in order to support ecologically friendly activities. In this study, biosynthetic ZnO nanoparticles were produced using Sentul (Sandoricum koetjape) peel extract under two distinct microwave irradiation powers (i.e., 360 W and 720 W) for three minutes. The effects of microwave irradiation power on the morphology and optical properties of ZnO were investigated. Prior to microwave irradiation, Sentul (Sandoricum koetjape) peel extract (20g/l) and zinc nitrate hexahydrate (0.2M) as a precursor were mixed homogeneously. Morphological, structural, and optical absorption of the samples were characterized using field effect scanning electron microscopy (FESEM), X-ray diffractometer (XRD), and UV-Vis spectroscopy, respectively. Surprisingly, the surface morphology of ZnO displays geometric forms resembling flowers. Higher irradiation power resulted in uniformly smaller ZnO nano-flowers. The crystal structure of both ZnO samples is wurtzite with a hexagonal structure. Maximum light absorption occurs at 349 nm and 358 nm, respectively, for ZnO samples subjected to 360 W and 720 W of microwave radiation. However, the bandgap energies are 3.29 and 3.28 eV, which is significantly less than the bandgap energy of bulk ZnO. (3.37 eV). According to the results, it is possible to control the form and size of ZnO nanoparticles using microwave heating.

Photoluminescence of Silver-Doped ZnO Nanostructures

The present work reviews the results of the photoluminescence (PL) study of silver-doped ZnO nanostructures synthesized by both physical and chemical methods. ZnO is a semiconductor with a binding energy of 60 meV, which ensures efficient near-band-edge band emission at a temperature of 300K and ultraviolet emission of bulk ZnO, and ZnO has a bandgap energy of 3.37 eV at room temperature. By tuning the growth process parameters of silver-doped ZnO nanostructures, the optical properties of ZnO can be controlled for use in various optoelectronic components, biosensors, blue-emitting diodes, and even white light sensors.

Antibacterial activity of green synthesized ZnO nano-flower using pineapple peel extract

Plant-based nanoparticles provide significant advantages over conventional physico-chemical techniques in medicine and biology. This paper reports the green route to synthesise ZnO particles using pineapple peel extract at various zinc precursor concentrations and evaluate their antibacterial activity. Morphological, structural, and optical properties of ZnO were characterised using SEM, XRD, FTIR, and UV–vis. The antibacterial potential of ZnO particles was evaluated against two clinical strains of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) using the paper disc diffusion method. SEM images exhibit flower-like ZnO with diameters in the range of 331–538 nm. The hexagonal wurtzite crystal phase of ZnO has been confirmed by XRD analysis with a crystal size of 14–17 nm. The FTIR spectrum has also validated the Zn-O bonding and the presence of additional functional groups in the samples. Antibacterial activity of the nanoflower ZnO towards E. coli and S. aureus displays inhibitory zone widths of 17.23 ± 3.03 mm and 30.14 ± 1.86 mm, respectively. These findings reveal that nanoflower ZnO produced using the pineapple peel extract exhibited a large bacterial inhibition zone, indicating that it is potentially used as food packaging or antibiotics.

Effect of strontium (Sr) doping on the structural, electronic and optical properties of ZnO, by first-principles calculations

We apply the first principles approach using the GGA-PBE + U approximation to study the effect of Sr doping on the structural, electronic and optical properties of ZnO. The computed results show that the optimized lattice parameters as well as the calculated band gaps of pure ZnO and Sr-doped ZnO (SZO) at low and high concentrations are in good agreement with the experimental data. Electronic investigations show that for low Sr concentrations, the appearance of Sr 5s states at a lower energy level than the Zn 4s states at the bottom of the conduction band, causes a reduction of the band gap. However, by increasing further the Sr content, the band gap increases because the Sr 5s states shift to higher energies. The calculated optical properties improve the optical performance of the SZO systems. Hence these findings provide a theoretical reference for future research on Sr-doped ZnO.

Solvothermal synthesis of ZnO with controllable morphology

ZnO structures were prepared by a two-step procedure. Firstly ZnO were synthesized by hydrothermal method with methanol as solvent and then annealed in air. The structure and morphology of the samples were analyzed by XRD and SEM. The chemical composition of the samples was determined by XPS. The optical properties were analyzed by fluorescence spectroscopy. The results show that the reaction time has an important influence on the morphology, chemical composition and optical properties of ZnO.

Studying the Structural and Optical Properties of ZnO how Prepared by oxidation free quick hating

In this study we oxidation thin film of Zinc on glass substrate in 510oC and oxidation time (10,20,30)sec . we intrusion the Zinc by using thermal diffusion. we exchange oven by appliance heater. the result show possibility relatively zinc oxide without using oxygen gas or closed oven and relatively so fast .this path is applied in production industrially and for large quantity. spectral analysis and elements analysis EDX explicit conversion zinc to zinc oxid purity 99% in oxidation time 30 sec . X-Ray analysis show that zinc oxid have Crystal system in crystal planes (002) and (101) .and AFM analysis show average nano dimension is 61.37nm .the study of optical properties clarifies the conversion. the result of energy gap for allow direct transmission 3.22eV and the energy gap for forbidden transmission 3.18eV .

Effect of Thickness on Electrical and Optical Properties of ZnO:Al Films

Zinc oxide (ZnO:Al) films were prepared on a substrate of different thicknesses by sputtering at 1×10−2 mbar argon gas pressure and 200 W power. The effect of film thickness on the structural, electrical, and optical properties was investigated by X-ray diffraction (XRD), 4-point probe technique, and ultraviolet-visible spectroscopy. The XRD film crystal structure study revealed that all sample films at thicknesses of 66, 106, 150 and 193 nm, respectively, exhibited planar Hexagonal wurtzite crystal structure (002), and ZnO crystals were grown along the c-axis. The ZnO:Al film at a thickness of 66 nm had the highest strain and the smallest crystal size compared to other films. The electrical resistivity decreases with increasing film thickness. The sample at 193 nm has the lowest resistivity (1.37 Ω.m). The results showed that light transmission revealed that all sample films had high transparency in the white and near-UV region at a wavelength of 350 to 800 nm, with an average light transmittance shift of 85 - 95 %. The energy band gap increased with the film thickness of 3.49(66 nm), 3.55(106 nm), and 3.59(150 nm) eV, and decreased to 3.57 eV at 193 nm, respectively. HIGHLIGHTS The different thicknesses Zinc oxide (ZnO:Al) films were prepared by sputtering at 1×10-2 mbar argon gas pressure and 200 W power was used to study the effect of film thickness on the structural, electrical, and optical properties The electrical resistivity changing of ZnO:Al film depends on the film thickness. The electrical resistivity is reduced with increasing ZnO:Al film thickness The ZnO:Al film are highlighted by their characteristics for light transmission at the wavelengths between 350 and 800 nm, and exhibited exceptional transparency in the white and near-UV range GRAPHICAL ABSTRACT

Structural, electronic and optical properties of ZnO and TiO2 nanoparticles for wastewater treatment: A first-principles study

Water quality deteriorates when industrial and human activities increase. This means that toxins must be removed from industrial and domestic wastewater. In the context of nanotechnology, anchoring TiO2 and ZnO nanoparticles on clay has also been shown to be potential sequesters and has been examined for wastewater treatment. This paper presents a thorough investigation of the structural, electronic, and optical featuresof ZnO & TiO2 nanoparticles using the GGA-PBE functional within the framework of density functional theory (DFT). For ZnO and TiO2 nanoparticles, there is excellent agreement between the calculated lattice parameters and the findings of the experiments. Electronic structure calculations confirm that both ZnO and TiO2 are semiconducting in nature. The density of states calculation reveals that the conduction band in TiO2 is primarily derived from hybridization between Ti-3d states and O-2p states, whereas the valence band is derived from mixing between Ti-3d and O-2p states. Further, ZnO, O-2p, andZn-3d states, primarily contributed to the valence band, while Zn-4 s and Zn-3p states mainly contributed to the conduction band. Since drinking water disinfection processes frequently involve ultraviolet (UV) absorption based advanced oxidation process. Investigations of the optical properties of these two materials suggest that ZnO and TiO2 show great potential as strong UV-absorbing and photocatalytic materials, and can be utilized as microbial disinfectants during wastewater treatment.

Theoretical study of structural and optical properties of ZnO in wurtzite phase

Our calculations are done with the help of density functional theory (DFT). Actually, we could find the structural and optical properties of the wurtzite-type ZnO compound. The pseudo-potential linearised augmented plane wave (PP-LAPW) method is applied to solve the Kuhn-Sham equations. The results are obtained using Both Generalized Gradient Approximation according to the scheme described by Perdew-Burke-Ernzerhof(GGAPBE) and Local Density Approximation according to the scheme described by CeperlyAlder (LDA-CA) approximations as two types of exchange-correlation. The convergence of energy and charge has been checked. This is in order to study the properties of the ground state. It was found that the primary cell constants calculated in the equilibrium state are very close to the previous theoretical works. The general results of optical properties including the imaginary part of the dielectric constant, reflectivity, absorption coefficient, refractive index, optical conductivity, and extinction coefficient of wurtzitephase ZnO under the imposed conditions are discussed and compared with previous works. Our results show new and important optical properties. Besides, we predicted the behavior of transparent conductive oxides in the direction of light

Investigations on structural, electronic and optical properties of ZnO in two-dimensional configurations by first-principles calculations

The electronic structures and optical properties of two-dimensional (2D) ZnO monolayers in a series of configurations were systematically investigated by first-principles calculations with Hubbard U evaluated by the linear response approach. Three types of 2D ZnO monolayers, as planer hexagonal-honeycomb (Plan), double-layer honeycomb (Dlhc), and corrugated tetragonal (Tile) structures, show a mechanical and dynamical stability, while the Dlhc-ZnO is the most energetically stable configuration and Plan-ZnO is the second one. Each 2D ZnO monolayer behaves as a semiconductor with that Plan-, Dlhc-ZnO have a direct band gap of 1.81 eV and 1.85 eV at the Γ point, respectively, while Tile-ZnO has an indirect band gap of 2.03 eV. Interestingly, the 2D ZnO monolayers all show a typical near-free-electron character for the bottom conduction band with a small effective mass, leading to a tremendous optical absorption in the whole visible and ultraviolet window, and this origination was further confirmed by the transition dipole moment. Our investigations suggest a potential candidate in the photoelectric field and provide a theoretical guidance for the exploration of wide-band-gap 2D semiconductors.

PH Controlled Nanostructure and Optical Properties of ZnO and Al-Doped ZnO Nanorod Arrays Grown by Microwave-Assisted Hydrothermal Method.

The low-temperature microwave-assisted hydrothermal method was used to successfully grow pure and Al-doped ZnO (AZO) nanorod (NR) arrays on glass substrates. The combined effects of doping and pH on the structural properties, surface chemistry, and optical properties of all samples were investigated. Thermodynamic-based simulations of the growth solution were performed and a growth mechanism, that considers the effects of both the pH and Al-doping, is proposed, and discussed. Tuning the solution pH is key parameter to grow well-aligned, single crystal, highly packed, and high aspect ratio nanorod arrays. Moreover, the optical absorption in the visible range is enhanced by controlling the pH value. The PL spectra reveal a shift of the main radiative emission from the band-to-band into a transition involving deep defect levels of Zinc interstitial Zni. This shift is caused by an enhancement of the non-radiative components (phonon relaxation) at high pH values. The production of well-ordered ZnO and AZO nanorod arrays with visible-active absorption/emission centers would increase their potential use in various applications.

Structural, optical, morphological and electrochemical properties of ZnO and graphene oxide blended ZnO nanocomposites

A simple cost-effective co-precipitation method was adopted to prepare ZnO nanoparticles from a metal organic framework. The synthesized ZnO nanoparticles were blended with graphene oxide (GO) to prepare the ZnO-GO nanocomposite. The physicochemical properties of ZnO nanoparticles and ZnO-GO nanocomposite were analyzed via various techniques. The structural behavior of ZnO and ZnO-GO nanocomposite was studied by XRD and FT-IR analysis. The XRD profile confirms the hexagonal structure with an average crystallite size of 19.4 nm for ZnO and 16.2 nm for ZnO-GO nanocomposites. The functional groups and the vibration modes of the samples were examined through FT-IR. It confirms the metallic presence in the ZnO and ZnO-GO samples in the wavenumber range of 400–600 cm−1. The optical properties of ZnO and ZnO-GO were studied via UV–vis spectra. The surface morphology of the samples was recorded through FESEM, and the elemental presence in the samples was examined by EDX. It confirms that the prepared samples are spherical in shape with uniform size distributions. Cyclic voltammetry has been used to study the redox behavior of electroactive ZnO and ZnO-GO composites.

Analysis of blue (BE), green (GE), yellow (YE), and red (RE) emission band in ZnO quantum dots

ZnO quantum dots (QDs) are prepared by the green technique of colloidal synthesis. Structural, morphological, and optical properties of ZnO (QDs) were investigated by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Photoluminescence. They were prepared ZnO (QDs) in different crystalline growth temperature ranges ∼60–210 ± 4 °C. Using the Hall-effect, we can measure the concentration of carriers, electronic mobility, and resistivity. The morphology and grain size distribution of ZnO (QDs) were analyzed by SEM. Through XRD studies, the hexagonal phase is identified and the grain size was estimated from Scherer’s method, situated at a range of ∼4.2–6.3 nm. Optical properties were investigated by UV-Vis spectroscopy. In Transmittance ( %T) studies, ZnO (QDs) reached ∼80 %, as well as a relative maximum shift at a range of ∼402–378 nm (∼3.08–3.28 eV). The Normalized Absorbance shows different relative maxima at UV-Vis, associated with VB→CB electronic transition and electronic intra-transitions assigned to intrinsic native crystalline defects located at ∼500–700 nm (∼2.48–1.77 eV), shows that the absorption bands originating from the F0 centers prevail over those of F+0 centers of VO when the intrinsic native crystalline defect concentration is high. The Tauc model was used to determine the optical gap energy of ZnO (QDs) is located at ∼3.08–3.26 eV, an optical phenomenon associated with quantum confinement. Photoluminscence (PL). PL signals show emission bands with different intensities: blue (YB), green (GE), yellow (YE), and red (RE) bands, situated in the Vis-region, and commonly associated with color points produced by vacancies and interstices crystalline. Interface passivation layer deposited onto photo anodes has been proven to be an available way to suppress charge recombination and enhance the power conversion efficiency in quantum dot-sensitized solar cells.