Optical Properties Of Zn1 Research Articles

Improvement of dielectric properties of ZnO nanoparticles by Cu doping for tunable microwave devices

We report a facile chemical polyol method to synthesize Cu-doped ZnO nanoparticles with various levels of Cu. X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–Visible diffuse reflectance spectroscopy techniques were used to analyze the structural and optical properties of Zn1−xCuxO nanoparticles. The crystallite size varies between 9.8 and 18.9 nm and decreased with the increase of Cu doping. The band energy gaps of pure and Cu-doped ZnO samples are in the range 2.5–3.1 eV. The dielectric properties, ac conductivity and impedance analysis of Zn1−xCuxO nanoparticles were systematically investigated. It was revealed that the doping of ZnO by Cu (with low Cu molar content) leads to obtain high dielectric constant and low tangent loss, which are very encouraging for microwave semiconductor devices.

An Investigation on Structural and Optical Properties of Zn1−xMgxS Thin Films Deposited by RF Magnetron Co-Sputtering Technique

In this paper, Zn1−xMgxS thin films were co-sputtered on glass substrates using ZnS and MgS binary target materials under various applied RF power. The compositional ratio of Zn1−xMgxS films was varied by changing the RF power at an elevated temperature of 200 °C. The structural and optical properties were studied in detail. The structural analysis shows that the co-sputtered Zn1−xMgxS thin films have a cubic phase with preferred orientation along the (111) plane. The lattice constant and ionicity suggest the presence of a zincblende structure in Zn1−xMgxS thin films. Zn1−xMgxS thin films have transmittance over 76%. The extrapolation of optical characteristics indicates that direct bandgaps, ranging from 4.39 to 3.25 eV, have been achieved for the grown Zn1−xMgxS films, which are desirable for buffer or window layers of thin film photovoltaics.

Spin polarized first principles calculations on electronic, magnetic and optical properties of Zn(1−x)AxS (A = Cr/Mn/Fe) using mBJ approximation

A systematic investigation on structural, electronic, magnetic and optical properties of Zn(1−x)AxS (A = Cr/Mn/Fe) are performed using first principles calculations within the frame work of spin polarized density functional theory (SP-DFT) as implemented in WIEN2k. The electronic, magnetic and optical properties are performed using the local spin density approximation (LSDA) coupled with modified Becke Johnson (mBJ) potential. The present results show that Zn(1−x)MnxS systems exhibit semiconducting behaviour whereas a half-metallic character is shown by both Zn(1−x)CrxS and Zn(1−x)FexS systems. Although undoped ZnS is a non-magnetic semiconductor, the calculated spin polarized density of states of Cr2+:ZnS and Fe2+:ZnS show 100% spin polarization at Fermi energy, EF. The optical properties, including the real and imaginary part of dielectric function, reflectivity, refractive index, absorption co-efficient, electron energy loss function and optical conductivity of undoped ZnS and Zn(1−x)AxS (A = Cr/Mn/Fe) systems are calculated using mBJ potential. The substitution of Cr and Fe in ZnS not only influences the position of absorption peaks of parent semiconductor in the UV region, but also leads to the formation of new narrow peaks in the visible and IR regions. A considerable red shift in the absorption peak due to the substitution of Fe and Cr shows a good agreement with the previous theoretical results. These outcomes imply that Zn(1−x)AxS (A = Cr/Fe) systems cover the spectral range from IR to near UV and seem to be the promising candidates for optoelectronic and spintronic applications.

Effect of thermal annealing on microstructure and optical properties of Zn1−xMgxO thin films grown by hydrothermal method

Zn1−xMgxO films were prepared by hydrothermal method to investigate the effect of thermal annealing on the microstructure and optical properties. The results show that the films exhibit mixed cubic-hexagonal phases. With increasing of calcination temperature from 500 to 1000 °C, the peak intensities of MgO (200) and ZnO in the XRD patterns increases, the absorption edge shows a blue shift. And the band gap broadens from 3.43 to 4.03 eV while the average transmittance from 450 to 750 nm decreases from 88 to 79 at.%. The first-principles calculations reveal that the Zn1−xMgxO is direct band gap semiconductor. When the Mg content in the Zn1–xMgxO films increases with rising the calcination temperature, the CBM determined by the Zn-4s and Mg-2p states shifts significantly to the high energy range and the VBM determined by the O-2p state holds constant at Gamma point. This is the main reason for the band gap broadening of the films with increasing the calcination temperature.

The chemical, phase composition and optical properties of Zn<sub>x</sub>Cd<sub>1-x</sub>S films obtained by close spaced vacuum sublimation

The chemical, phase composition and optical properties of Zn<sub>x</sub>Cd<sub>1-x</sub>S films obtained by close spaced vacuum sublimation

Band Gap Engineering of Mg Doped ZnO Nanorods Prepared by a Hydrothermal Method

AbstractThe effect of band gap on the structure, magnetic, and optical properties of Zn1−xMgxO nanorods synthesized by hydrothermal method using varying x‐values from 0.00 to 0.05 with 0.01 step increment is studied. The structural phases of Zn1−xMgxO samples are determined by X‐ray diffraction tool. The Rietveld analysis is performed for the selected Zn0.95Mg0.05O sample and all samples’ phases are found as single phase. The concentration‐dependent of lattice parameters, cell volumes, microstrain, and dislocation density, locality of the atoms and their displacement, and bond length in Zn1‐xMgxO structures are detailed. Electron Spin Resonance (ESR) measurements are performed and analyzed through concentration dependence of the g‐factor and the line‐widths of pike to pike (ΔHPP) of ESR spectra. A ferromagnetic behavior of the Zn0.95Mg0.05O nanorods is observed. The optical band gaps (Eg) of Zn1‐xMgxO nanorods are obtained by the data taken from Ultraviolet–Visible (UV–VIS) diffuse reflectance spectroscopy. It is found that the Eg‐values increased with increasing amount of Mg elements in the structure.

Effect of thickness on structure and optical properties of Zn0.9Co0.1Oδ thin films deposited by magnetron sputtering in oxygen gas environment

Abstract Zn0.9Co0.1Oδ thin films have been deposited by radio frequency magnetron sputtering onto fused quartz substrates under oxygen gas environments as a function of film thickness (time duration). The as deposited films show hexagonal wurtzite structure of ZnO with films orientated in (0 0 2) plane perpendicular to base plane, without any secondary phases of CoO in host ZnO matrix. The crystallite (D) values estimated from XRD plots show increases with film thickness. The microstructural images recorded with field emission scanning electron microscopy (FE-SEM) have dense microstructure with an average grain size varies about ∼28–43 nm. The elemental composition of thin films were examined by energy dispersive spectroscopy confirms presence of Co in ZnO. The films have optical transmission in the visible region is about 55–70%, the absorption edge shifts towards low energy range with increase in film thickness. The estimated optical energy band gap of as deposited films shows a decreasing trend as a function of film thickness. The optical energy band gap for all the films are listed is varies about 3.42–2.85 eV respectively.

Structural and Optical Properties of Zn1‐xMgxO Prepared by Calcination of ZnO + Mg(OH)2 after Hydro Micro Mechanical Activation

AbstractZn1‐xMgxO microcrystals are produced in the 0.15 ≤ x ≤ 1 composition range by calcination of ZnO + Mg(OH)2 after hydro micro mechanical activation according to the patent WO2018065735A1. The structural properties of the samples have revealed the cohabitation of wurtzite and rock‐salt phases for x values ranging from 0.15 up to 0.6 with a clear increase of the proportion of cubic phase with x. A single cubic phase is observed in the range 0.66 ≤ x < 1. From the purity of these samples produced at very low cost, it is expected that they will be used as precursors for growth of advanced light emitters integrated into an already existing process as they exhibit exceptionally efficient (and robust with T) light emission in the ultraviolet region.

Effect of Zn1−xMgxS Doping on Structural, Thermal and Optical Properties of PVA

The optical properties of Zn1−xMgxS/PVA nanocomopsite prepared via casting technique are investigated over the spectral region of 200–800 nm. Structural property studies were performed using X-ray diffraction and transmission electron microscopy techniques. The thermal stability of pure and doped PVA polymers was examined by differential scanning calorimetry. Various optical parameters such as, the optical energy gap, single oscillator energy, refractive index, dispersion energy, optical dielectric constant and Urbach energy have been calculated and discussed with respect to the formed chemical bonds that present in the PVA system with the existence of Mg dopants in Zn1−xMgxS nanoparticles with different concentrations up to 10%.

Optical absorption in full composition range of ZnCuO thin films synthesized by spray pyrolysis

A systematic investigation of the structural, morphological, and optical properties of Zn1 − xCuxO thin films (0 ≤ x ≤ 1) is presented. The films were produced by spray pyrolysis on top of glass substrates employing a clean acetate chemical route. X-ray diffraction patterns show the polycrystalline character of the films without secondary phases in wurtzite (up to x = 0.10) and monoclinic (above x = 0.90) symmetries. The intermediate concentrations present both phases. Electron microscopy images exhibit homogeneous surface with increasing roughness as the amount of copper increases. For intermediate Cu concentrations, the films present phase segregation with constant optical absorption coefficient around 2 × 104 cm− 1 in the visible range, while a larger tunable absorbance is available for higher Cu concentrations. The indirect bandgap is reported for Zn1 − xCuxO with x > 0.25, whereas the CuO direct bandgap absorption is very sensitive to the introduction of Zn in the lattice.

Effects of hydrogen insertion on electronic, magnetic and optical properties of Co-doped ZnO: A theoretical investigation

In this contribution, we adopted density functional theory and the Hubbard-U method for the investigation of the electronic, optical and magnetic properties of H-Co-codoped ZnO. Calculations indicate that interstitial hydrogen prefers to bond with oxygen atom in the Co-O bond center. Also the existence of interstitial hydrogen decreases the local magnetic moment of Co in Zn0.963Co0.037O. The hydrogen implantation decreases the magnetic moment in the Zn0.963Co0.037O. Calculations are done for different doping concentrations to discuss the hydrogen effect on magnetic and optical properties of Zn0.963Co0.037O.

Structural, Electrical and Optical Properties of Zn0.94Mn0.04Li0.02O Nanocrystals

Structural, Electrical and Optical Properties of Zn_0.94Mn_0.04Li_0.02O Nanocrystals

Thickness effects on physical and electrical properties of Zn0.97Co0.02In0.01O thin films grown by magnetron sputtering RF

The effects of thickness on physical properties (structural, morphological, optical and electrical) of Zn0.97Co0.02In0.01O (CIZO) thin films with different thicknesses grown at room temperature were investigated in this study. Zn0.97Co0.02In0.01O thin films have been grown by Radio Frequency magnetron sputtering on glass substrate followed by a rapid annealing treatment at 400 °C for 10 min. X-ray diffraction (XRD) measurement display that the Zn0.97Co0.02In0.01O thin films exhibited hexagonal wurtzite phase with a preferred orientation along the c-axis. We observe a strong single peak corresponding to the (002) phase obvious on the diffractograms. The crystallite size values exhibit an increasing tendency and the dislocation density indicates a decreasing trend with increasing thickness, this shows that the material is relaxing. Concerning the SEM micrographs, it was observed that the average grain size increased from 20 nm to 80 nm, with thickness ranging from 150 nm to 450 nm. The roughness surface (RMS) measured by AFM increased from 4.309 nm to 11.392 nm with a rising thickness. Raman spectroscopy was used to study structural properties of complex oxides at a local level. All films were highly transparent in the visible region with an average transmittance of 96%. Growing the thickness enhance the optical band gap, from 3.106 eV to 3.439 eV. Optical parameters such as absorption coefficient, refractive index, dispersion parameters and dielectric constants were studied to investigate the influence of thickness on optical properties of Zn0.97Co0.02In0.01O thin films. The thickness improves the electrical resistivity of Zn0.97Co0.02In0.01O thin films. It has been found from electrical measurements that films with a thickness of 450 nm have the lowest resistivity of 2.9 10−3 Ω cm. Once the merit factor determined, we noted that the 450 nm sample having a better TCO of value 12.2 103Ω−1.

Preparation, growth and characterization of nonvacuum Cu-doped ZnO thin films

We investigated the effects of increasing Cu dopant concentration on the microstructure and optical properties of Zn1−xCuxO thin films. The transparent Zn1−xCuxO solution concentrations were varied from x = 0.0 to x = 0.05 with an increment of 0.01. All nano films were prepared by dip coating system using the sol-gel method. X-ray diffraction (XRD) measurements, scanning electron microscopy (SEM) observations, energy-dispersive X-ray spectroscopy (EDS) analyses, and atomic force microscopys (AFM) analyses revealed a fine-grained structure resulting from doping of Cu into the ZnO structure. In addition, UV–Vis spectrophotometer was used to determine the optic properties of ZnO based nano thin films. XRD analysis also showed that the undoped ZnO and Cu-doped ZnO films oriented along the (002) as the dominant plane. In the 400–700 nm wavelength range, a decrease in transparency was observed in the Zn1−xCuxO thin films with increasing Cu concentration. Although the optical band gap of the Cu-doped ZnO thin films was lower than that of the undoped ZnO thin film, the Urbach energy of the all of the doped thin films was higher than the undoped ZnO thin film.

Optical properties of spin coated Co0.6Zn0.4Mn0.3Fe1.7O4 thin films deposited on silicon and platinum coated silicon substrates

ABSTRACTThis work presents optical properties of Zn and Mn co-doped CFO (Co0.6Zn0.4Mn0.3Fe1.7O4) films deposited on Si and Pt coated Si substrates by spin coating technique. X-ray diffraction pattern of the films exhibited spinel cubic structure with polycrystalline phase. Optical characteristics of the CZFMO films are studied using photoluminscence and UV-visible spectroscopy. With the rise in annealing temperature, quenching in PL emission was observed for films grown on silicon; whereas a marginal enhancement in emission was observed for films deposited on the Pt / Si substrate. Optical band gap of the films are found to vary between 2.3 – 2.7 eV range.

Examination of electrical and optical properties of Zn1 − xMgxO:Al fabricated by radio frequency magnetron co-sputtering

ZnO:Al is widely used as transparent conductive oxide (TCO) layer in several electronic and optical devices. To widen bandgap energy (Eg) of ZnO:Al, Mg was introduced to form Zn1−xMgxO:Al. In this work, the Zn1−xMgxO:Al films with different [Mg]/([Mg]+[Zn]) ratios (Mg content (x)) on soda-lime glasses and polycrystalline Cu(In,Ga)Se2 thin films were prepared by radio frequency magnetron co-sputtering of ZnO:Al and MgO targets. The power density applied to ZnO:Al target was constant at 144.3W/cm2, whereas that applied to MgO target is varied from 0 to 183.7W/cm2 to change the [Mg]/([Mg]+[Zn]) ratio from 0 to 0.205. It is demonstrated that Eg of the Zn1−xMgxO:Al is increased with the [Mg]/([Mg]+[Zn]) from 0 to 0.205, while the basic crystal structure is ZnO. The Zn1−xMgxO:Al films with small [Mg]/([Mg]+[Zn]) ratios of approximately 0.064–0.139 possess the better film quality and higher Hall mobility than those of ZnO:Al since their crystalline diameters are enhanced with the decreased deep-defect levels. With the small [Mg]/([Mg]+[Zn]) up to 0.139, the carrier concentration is decreased, which is beneficial to lower the free carrier absorption, while the resistivity is kept low. Consequently, the Zn1−xMgxO:Al films with the small [Mg]/([Mg]+[Zn]) ratio (about 0.064–0.139) are promisingly utilized as TCO layer.

Effect of substrate on the structural transformation and optical properties of Zn1 − xMgxO thin films grown by pulsed laser deposition

Pulsed laser deposited MgxZn1−xO films grown on sapphire substrates exhibited wurtzite hexagonal structure at lower Mg concentrations (x<0.20), whereas use of MgO substrates promotes cubic rocksalt structure. For x≥0.20, single-phase cubic ZnMgO thin films with 〈200〉 orientation were realized on MgO substrates. However, the films grown on sapphire substrates exhibited single-phase cubic structure with 〈111〉 orientation only when x≥0.4. We show that the optical bandgap of wurtzite ZnMgO films can be tuned from 3.27eV to 3.80eV. On the other hand cubic ZnMgO films exhibited larger bandgap values as high as 5.99eV.

Structural, electronic, magnetic and optical properties of semiconductor Zn1−xMoxTe compound

The structural, electronic, magnetic and optical properties of the Zn1−xMoxTe (x = 0.00, 0.25, 0.50, 0.75, 1.00) have been investigated by the spin-polarized first-principles calculations. The Zn0.50Mo0.50Te has tetragonal structure while the Zn1−xMoxTe (x = 0.00, 0.25, 0.75, 1.00) crystallize in cubic structures. For Zn1−xMoxTe (x = 0.25, 0.50, 0.75, 1.00) alloys, the lattice constant and the volume are found larger than those of pure ZnTe alloy. The Zn1−xMoxTe (x = 0.25, 0.50, 0.75, 1.00) is magnetic and the Mo element is found dominant in the bands crossing the Fermi level in the spin-up channel. The Zn0.75Mo0.25Te and MoTe have half-metallic (HM) behavior. In spin-down channel of the Zn0.75Mo0.25Te, the Zn atom mainly contributed to the conduction band minimum (CBM), while the valence band maximum (VBM) appears mainly due to contribution of Te element. A positive spin splitting and crystal field splitting of d-states of Mo atom has been observed for Zn0.75Mo0.25Te alloy. The maximum values of the absorption coefficients αMAX(ω) of the Zn0.50Mo0.50Te alloy along a or b axes are smaller than the absorption coefficient along c axis. The first absorption peak appearing in the energy range of 0.000–1.000 eV for Zn1−xMoxTe (x = 0.25, 0.50, 0.75 or 1.00) alloys is the new peak which is not observed in ZnTe.

Studies of the Crystal Structure and Optical Properties of Zn$_{0.95}$Mn$_{0.05}$S Epilayers

Studies of the Crystal Structure and Optical Properties of Zn$_{0.95}$Mn$_{0.05}$S Epilayers

First-principles calculations to investigate the structural, electronic and optical properties of Zn1−xMgxTe ternary alloys

First-principles calculations based on the full potential muffin-tin orbitals method (FP-LMTO) within the local density approximation (LDA) and generalized gradient approximation (GGA) used to study the structural, electronic and optical properties of Zn1−xMgxTe ternary alloy are presented. The lattice parameter, bulk modulus, energy gap, refractive index, optical dielectric constant and effective masses for Zn1−xMgxTe ternary alloy with compositions x= 0, 0.25, 0.5, 0.75, 1 are investigated. The refractive index and optical dielectric constant using specific models are verified. Our calculated results are in good agreement with the available theoretical and experimental data.