Abstract:In this work, the electronic structure and optical properties of Mg 1−x Zn x O (0 ≤ x ≤ 0.5) are investigated within the framework of the density functional theory (DFT), the GW method, and the Bethe-Salpeter equation (BSE). We find that zinc doping can lower the band gap of pure MgO via the Zn 4s states near the Fermi level and reduce the lattice symmetry, both of which will affect the optical properties. The energy of the first absorption peak decreases as the concentration of zinc increases, so are the exci… Show more
“…The strongest ultraviolet luminescence (UVL) was shifted to 3.21 eV (ZN1), 3.20 (ZN3) and 3.16(ZN5) as the Zn dopant concentration in samples increased. It can be seen that three remain peaks were redshifted, in agreement with [26]. The redshift of about ~0.08 -0.13 eV in the three observable excitation spectra might due to the size effect, occurrence of defects and mechanical stress from the bending of the MgO.…”
Section: Morphology Of Particlessupporting
confidence: 82%
“…The bonding states between Zn and O shifted the conduction band toward lower energies thus reducing the band gap. The effect of this hybridization to the band gap was predicted using density functional theory (DFT) and GW calculation reported elsewhere [26]. Photoluminescence spectra of doped MgO were recorded upon excitation at 4.59 eV as shown in Fig.…”
Spherical particles of Zn doped MgO were prepared by one-step spray pyrolysis method. The crystalline nature and particle size of the samples were characterized by X-ray diffraction analysis (XRD). The morphology of samples was studied by scanning electron microscope (SEM) and the presence of Zn in the sample was confirmed by energy dispersive X-ray analysis (EDX). The optical properties of the samples were investigated using photoluminescence spectroscopy (PL) analysis to obtain excitation and emission spectra of the samples. Results indicated that the doped MgO particles exhibited a cubic structure without hexagonal wurtzite structure as the Zn concentrations were increased. Spherical shape and porous particles are found with increasing of doping concentration. The optical band gap of MgO altered with the addition of doping concentration. A considerable redshift of about ~0.08 -0.13 eV in the excitation spectra of 2.22 eV emission band was revealed in Zn doped MgO samples. It was highlighted that Zn doped MgO prepared by the spray pyrolysis generated emission at UV-Vis wavelength required for many applications.
“…The strongest ultraviolet luminescence (UVL) was shifted to 3.21 eV (ZN1), 3.20 (ZN3) and 3.16(ZN5) as the Zn dopant concentration in samples increased. It can be seen that three remain peaks were redshifted, in agreement with [26]. The redshift of about ~0.08 -0.13 eV in the three observable excitation spectra might due to the size effect, occurrence of defects and mechanical stress from the bending of the MgO.…”
Section: Morphology Of Particlessupporting
confidence: 82%
“…The bonding states between Zn and O shifted the conduction band toward lower energies thus reducing the band gap. The effect of this hybridization to the band gap was predicted using density functional theory (DFT) and GW calculation reported elsewhere [26]. Photoluminescence spectra of doped MgO were recorded upon excitation at 4.59 eV as shown in Fig.…”
Spherical particles of Zn doped MgO were prepared by one-step spray pyrolysis method. The crystalline nature and particle size of the samples were characterized by X-ray diffraction analysis (XRD). The morphology of samples was studied by scanning electron microscope (SEM) and the presence of Zn in the sample was confirmed by energy dispersive X-ray analysis (EDX). The optical properties of the samples were investigated using photoluminescence spectroscopy (PL) analysis to obtain excitation and emission spectra of the samples. Results indicated that the doped MgO particles exhibited a cubic structure without hexagonal wurtzite structure as the Zn concentrations were increased. Spherical shape and porous particles are found with increasing of doping concentration. The optical band gap of MgO altered with the addition of doping concentration. A considerable redshift of about ~0.08 -0.13 eV in the excitation spectra of 2.22 eV emission band was revealed in Zn doped MgO samples. It was highlighted that Zn doped MgO prepared by the spray pyrolysis generated emission at UV-Vis wavelength required for many applications.
“…This attenuation length is comparable to the electron-hole binding distance (about 6 nm in MgO (ref. 43 )), which highlights the significance of these surface-localized excitons in our measured spectra. Fig.…”
Strong-field methods in solids enable new strategies for ultrafast nonlinear spectroscopy and provide all-optical insights into the electronic properties of condensed matter in reciprocal and real space. Additionally, solid-state media offers unprecedented possibilities to control high-harmonic generation using modified targets or tailored excitation fields. Here we merge these important points and demonstrate circularly-polarized high-harmonic generation with polarization-matched excitation fields for spectroscopy of chiral electronic properties at surfaces. The sensitivity of our approach is demonstrated for structural helicity and termination-mediated ferromagnetic order at the surface of silicon-dioxide and magnesium oxide, respectively. Circularly polarized radiation emanating from a solid sample now allows to add basic symmetry properties as chirality to the arsenal of strong-field spectroscopy in solids. Together with its inherent temporal (femtosecond) resolution and non-resonant broadband spectrum, the polarization control of high harmonics from condensed matter can illuminate ultrafast and strong field dynamics of surfaces, buried layers or thin films.
“…In parallel, the resistivity increased from 109 to 1268 Ω cm and the mobility increased from 0.01821 to 53.08 cm 2 /(V.s). The decreased charge carriers' density could be attributed to the fact that the conduction band (CB) of pure ZnO consists mainly of O 2p and Zn 4s states [53,54], so the introduction of Mg in ZnO thin lms will reduce the Zn 4s state and introduce Mg 3p state which has high energy relative to the Zn 4s [55,56]. Moreover, the widening in the optical bang gap energy discussed previously, could also in uence the free charge carriers' density since the electrons passing from the valance band must requires higher energy to access the conduction band.…”
Mgx Zn 1−x O thin lms were deposited on glass substrate with x varied between 0.01 and 0.05 by spray pyrolysis at a temperature of 450 °C. The structural investigation showed that all thin lms had ZnO wurtzite structure with a preferred (002) orientation. The gap energy was calculated using Tauc's plot and it decreased over the Mg content by 0.07 eV. The charge carriers' density dropped by an order of 10 5 as Mg content increased whereas the resistivity and the mobility increased. SEM observations revealed a signi cant difference between undoped and doped thin lms. A 632.8 nm laser source prism coupler revealed 2 optical modes for every thin lm in each Transverse Electric and Transverse Magnetic mode, the birefringence of the Mg doped lms was positive. Both ordinary and extraordinary refractive indexes were found to decrease as the Mg content increased. Great intention has been paid to the relation between the refractive, charge carriers density and the optical band gap.
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