Optical Properties Of Zn1 Research Articles

Influence of deposition parameters on the structure and optical property of Zn(S,O) films

This paper presents the influence of process parameters, including sputtering power, oxygen partial pressure (R O), and substrate temperature on the optical property of Zn(S,O) thin films fabricated by radio frequency magnetron sputtering technology and deposited on glass substrates. The chemical composition, structural and optical properties of the samples were investigated by electron spectroscopy for chemical analysis, X-ray diffraction, and spectrophotometer. All the films mainly exhibited β-ZnS phase with (111) preferred orientation. [S]/([S]+[O]) ratio increased at high sputtering power, low RO, and low substrate temperature. Moderate ranges in sputtering power and substrate temperature and low RO resulted in large grain size. Adatoms are expected to exhibit increased mobility under these conditions. Average transmittance exceeded 75% in the visible wavelength region. Bandgap under these conditions was dominated strongly by the change in grain size and [S]/([S]+[O]) ratio. Optical properties of Zn(S,O) thin films could be modified, which is promising for optoelectronic applications.

Zn、Cu共掺杂TiO2 ∶SiO2薄膜材料的光学性能研究

Zn、Cu共掺杂TiO₂ ∶SiO₂薄膜材料的光学性能研究

Study of magnetic and optical properties of Zn1−xTMxTe (TM = Mn, Fe, Co, Ni) diluted magnetic semiconductors: First principle approach

We present structural, magnetic and optical characteristics of , calculated through Wien2k code, by using full potential linearized augmented plane wave (FP-LAPW) technique. The optimization of the crystal structures have been done to compare the ferromagnetic (FM) and antiferromagnetic (AFM) ground state energies, to elucidate the ferromagnetic phase stability, which further has been verified through the formation and cohesive energies. Moreover, the estimated Curie temperatures Tc have demonstrated above room temperature ferromagnetism (RTFM) in . The calculated electronic properties have depicted that Mn- and Co-doped ZnTe behave as ferromagnetic semiconductors, while half-metallic ferromagnetic behaviors are observed in Fe- and Ni-doped ZnTe. The presence of ferromagnetism is also demonstrated to be due to both the p–d and s–d hybridizations between the host lattice cations and TM impurities. The calculated band gaps and static real dielectric constants have been observed to vary according to Penn’s model. The evaluated band gaps lie in near visible and ultraviolet regions, which make these materials suitable for various important device applications in optoelectronic and spintronic.

Structural stability, electronic, magnetic and optical properties of zincblende Zn0.5V0.5Te under pressure

The structural stability, electronic, magnetic and optical properties of zincblende Zn0.5V0.5Te under pressures 0–5 GPa are investigated by the spin-polarized first-principles calculation. Under pressure, the Zn0.5V0.5Te is always half-metal with the total magnetic moment μtot of 3μB/cell mainly contributed by V2+ ion, but the spin-down channel opens a band gap. The Zn0.5V0.5Te also behaves in a ductile manner and is mechanical stable until 3.78 GPa pressure. The static dielectric function ε1(0) and refractive index n(0) increase with pressure. The two absorption peaks located in energy regions 0–20 eV and 35–50 eV not only increase but also shift to the higher energy region (blue shift) with pressure. So the electronic and optical properties of Zn0.5V0.5Te could be tuned through external pressure, which is beneficial to the electronic and optical applications.

Effect of annealing on optical properties of Zn doped NiO thin films deposited by magnetron sputtering.

Effect of annealing on optical properties of Zn doped NiO thin films deposited by magnetron sputtering.

Effect of post-annealing temperature on structure and optical properties of Zn1−x Cd x O thin films synthesized by magnetron sputtering

The Zn1−x Cd x O (x = 0.5) thin film was grown on quartz by the direct current reactive magnetron sputtering and post-annealing techniques. The influence of annealing temperature (T a) on the structure and optical properties of Zn1−x Cd x O thin film was investigated by using X-ray diffraction (XRD), photoluminescence and optical absorbance measurements. The XRD results indicate that the as-grown Zn1−x Cd x O thin film is of highly (002)-preferred orientation and possessing the hexagonal wurtzite structure of pure ZnO, as the T a increases up from 300 to 600 °C, the phase segregation as cubic CdO was observed. The detailed microstructures of the Zn1−x Cd x O thin film were investigated by transmission electron microscopy. Moreover, with the increase of T a, the optical band gap of the Zn1−x Cd x O thin films increased from 2.08 to 3.14 eV. Correspondingly, the near-band-edge photoluminescence was tuned in a wide visible region from ~588 to 403 nm.

Electronic and optical properties of Zn0.75Cd0.25S1−zSez first-principles calculations based on the Tran–Blaha modified Becke–Johnson potential

The energy band gap of Zn0.75Cd0.25S1−zSez (x=0, 0.25, 0.5, 0.75 and 1.0) quaternary alloys have been calculated by using the full-potential linearized augmented plane wave (FPLAPW) method and the Tran–Blaha modified Becke–Johnson (TBmBJ) potential. The lattice volume was first relaxed within the generalized gradient approximation (GGA). The obtained values of the band gaps are found to decrease linearly from 3.61eV down to 2.83eV as the content of the Se ion increases in the lattice. These values are in agreement with those reported experimentally for some of ZnS and ZnSe structures. The energies of the interband transitions were determined from the dielectric functions. It is seen that the main interband transitions peaks obtained after the TBmBJ potential is comparable with some reported experimental data. These finding supports the use of the TBmBJ potential as an accurate method in obtaining the energy band gap and the optical constants of semiconductors.

Structural and optical analyses of polycrystalline Zn1−xSbxSe thin films prepared by resistive heating technique

Here we report the influence of Sb doping on the structural and optical properties of Zn1−xSbxSe (0⩽x⩾0.15) thin films prepared by thermal evaporation technique on glass substrate. Various characterization techniques such as X-ray diffraction (XRD), EDS, Raman spectroscopy and spectroscopic ellipsometer are employed to assess the structural and optical properties of the deposited films. XRD analysis reveals the formation of polycrystalline cubic structure having preferred growth orientation along (111) plane without any evidence of secondary phases. Crystallographic parameters like grain size, micro strain, dislocation density, number of crystallites per unit area and texture coefficient point out the structural modification in ZnSe films with Sb inclusion. Raman analysis shows the existence of three 1LO, 2LO and 3LO phonon modes at 251, 511 and 745cm−1 in pure ZnSe while 3LO mode disappears by the incorporation of Sb atoms in ZnSe matrix. Increase in FWHM of Raman peaks with Sb concentration also indicates the change in crystalline quality of ZnSe films which is in accordance with our XRD results. Spectroscopic ellipsometry results demonstrate a decreasing trend for the optical band gap energy (from 2.61eV to 1.81eV) with increasing Sb content.

Structural, electronic and optical properties of Zn0.5Cr0.5S from first-principles

The structural, magnetic, electronic and optical properties of the Zn0.5Cr0.5SZB, Zn0.5Cr0.5SW and Zn0.5Cr0.5SRS are studied by spin-polarized first-principles calculation. After optimization Zn0.5Cr0.5SZB system changes its original cubic structure of ZnSZB to a tetragonal structure, while Zn0.5Cr0.5SW and Zn0.5Cr0.5SRS still remain their original hexagonal structure of ZnSW and tetragonal structure of ZnSRS, respectively. The total moments of these Cr doped ZnS systems are mainly contributed by local magnetic moments of Cr2+ ion. Zn0.5Cr0.5SZB, Zn0.5Cr0.5SW and Zn0.5Cr0.5SRS are all half-metal with 100% spin polarization. The Zn0.5Cr0.5SW has the biggest static dielectric constant ɛ1(0) and refractive index n(0). The Zn0.5Cr0.5SZB, Zn0.5Cr0.5SW and Zn0.5Cr0.5SRS have tow absorption regions in the ranges of 0–27eV and 41–55eV, but the absorption width decreases for Zn0.5Cr0.5SW, Zn0.5Cr0.5SZB and Zn0.5Cr0.5SRS successively. The results will give a guide for design and application of the Zn0.5Cr0.5SZB, Zn0.5Cr0.5SW and Zn0.5Cr0.5SRS in spintronic devices and optical detectors.

Effect of doping on structural, physical, morphological and optical properties of Zn1−xMnxO nano-particles

The effect of Mn doping on the structural physical, morphological and optical properties of Zn1−xMnxO nanoparticles prepared by novel co-precipitation route. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–vis spectroscopy. Broad peaks observed in XRD patterns indicates that all samples were nanocrystalline with hexagonal phase. Studied lattice parameters and volume of unit cell as a function of Mn content. The crystalline size, lattice strain, stress and strain energy density of Mn doped ZnO nanoparticles were determined from XRD patterns using W–H three models. The results obtained yields strain, stress and strain energy density increases with increasing Mn content and crystalline size decrease. Among the developed models, UEDM model was observed to be the best fit for co-precipitation route. The transmission electron microscopy (TEM) result confirms that mean particle size of Zn1−xMnxO nanoparticles were about 20–27nm. The optical study shows the decrease in optical energy band gap with Mn doping and confirm that Mn2+ ions substituting in ZnO materials. The u parameter and bond length of Mn doped ZnO nanoparticles were also investigated in this paper.

Electronic and optical properties of Zn(Cu,V)O studied by first principles

We used first principles to study the electronic and optical properties of Zn(Cu,V)O. These properties also compared with ZnO, Zn(Cu)O and Zn(V)O. The calculated formation energy shows Zn(Cu,V)O is easy formed in an oxygen condition. After Cu and/or V doping, the band and density of states (DOS) shift to lower energy. The shift comes from the released free electrons. The band gradually becomes complex with Cu and/or V doping, which can induce colorful optical properties. The relation between band and DOS has been discussed. Zn(Cu)O has an absorption in the lower energy, while Zn(V)O has a red shift in optical properties in the ultraviolet region. The Cu and V codoping synthesizes the merits of separate doping. The absorption of Zn(Cu,V)O has a red shift and a little peak at lower photon energy. The relation between optical properties and DOS has also been discussed. The red shift and lower-energy peak can better the performance of Zn(Cu,V)O as photocatalysis or solar cell. The other optical properties have also been calculated. Our study not only can help us comprehend the related experiments, but also provide a method to better the performance of ZnO.

Effect of Al doping concentration on the electrical and optical properties of sol–gel derived Zn0.87Mg0.13O thin film

Zn0.87Mg0.13O thin film was developed by the sol–gel process. The effect of the Al doping concentration on the electrical and optical properties of Zn0.87Mg0.13O thin film was investigated. The lowest resistivity of 7.96 × 10−3 Ω·cm with an optical bandgap energy of 3.64 eV was achieved at a doping concentration of 0.8 mol % in solution (0.6 at. % in film). Al doping contributes to the decrease of resistivity and the increase of optical bandgap energy, whereas heavy doping of greater than 0.8 mol % shows detrimental effects on the resistivity and film crystallinity. The mobility is dominated by grain boundary scattering.

Optical properties of Zn1−x Al x O:NiO transparent metal oxide composite thin films prepared by sol–gel method

The films of Zn1−x Al x O:NiO (AZO; Al/Zn = 1.5 at.%, x = 0.5–2.0) were synthesized on glass substrates by sol–gel method. The morphological properties of the films were studied by atomic force microscopy. The surface morphology of the films is found to depend on the concentration of NiO. The optical band gap, Urbach energy and optical constants such as refractive index, extinction coefficient and real and imaginary parts of the dielectric constant of the films were determined. The refractive index dispersion of the films obeys the single-oscillator model, and the single-oscillator parameters were determined. The optical band gap of ZnO film was found to be 3.76 eV, and the optical band gap of the films increases with NiO doping. The obtained results suggest that Zn1−x Al x O:NiO films can be used as optical material in optical communication applications.

Structural, microstructural, and optical properties of Zn1−x Mg x O thin films grown onto glass substrate by ultrasonic spray pyrolysis

Pure and doped Zn1−x Mg x O films were deposited onto glass substrate by ultrasonic spray pyrolysis technique. The variation of lattice constant and the blue shift of near-band-edge emission indicate that Zn2+ ions are successfully substituted by Mg2+ ions within ZnO lattice. At higher Mg content (x ≥ 0.21), a drastic change appears in the morphology, as a result of structural changes from wurtzite (ZnO) structure into a mixture of wurtzite and cubic (MgO) phases. FTIR study indicated the existence of distinct characteristic absorption peaks at ~442 cm−1 for Zn–O stretching mode that shifted toward the red region with the increase in Mg content. In addition to the host phonons of ZnO, one additional band was observed around 523 cm−1, presumably attributed to the Mg-related vibrational mode. The optical constants and thickness of thin films have been determined using experimental transmittance data. The luminescence intensity at 2.63 eV of Zn0.85Mg0.15O thin films was found to be approximately 13 times higher than that of pure ZnO film measured under the same excitation conditions.

Structural, electrical, and optical properties of Zn–In–Sn–O films for silicon heterojunction solar cells

We investigated the structural, optical, and electrical properties of Zn–In–Sn–O (ZITO) films prepared by RF magnetron sputtering for silicon heterojunction solar cells. The effects of Zn addition on the properties of the as-grown films were examined. XRD patterns of the ZITO films deposited at room temperature showed a broad peak. The cross-sectional TEM image of ZITO films at low Zn levels exhibited a typical fine or nanostructure embedded in an amorphous phase. On the other hand, at higher Zn addition, the films exhibited a completely amorphous phase. The carrier concentration decreased with increasing Zn content. The lowest electrical resistivity of 5.5×10-4Ωcm was observed for a ZITO film with 4.83 Znat.%. All ZITO films grown in this study showed transmittance of over 80% in the visible and near-infrared spectral range. The absorption was less than 5% in the visible region.

Effect of Ni doping on structural and optical properties of Zn1−xNixO nanopowder synthesized via low cost sono-chemical method

Zn1−xNixO nanopowders with different Ni contents of x=0.0, 0.04 and 0.08 were synthesized via cost effective sonochemical reaction method. X-ray diffraction (XRD) pattern reveals pure wurtzite phase of prepared nanostructures with no additional impurity peaks. The morphology and dimensions of nanoparticles were investigated using scanning electron microscope (SEM). A sharp and strong peak for first order optical mode for wurtzite zinc oxide (ZnO) structure was observed at ∼438cm−1 in Raman spectra. The calculated optical band gap (Eg) from UV–vis transmission data was found to decrease with increase in Ni content. The observed red shift in Eg with increasing Ni content in ZnO nanopowders were in agreement with band gap behaviours found in their photoluminescence (PL) spectra. The synthesised ZnO nanopowders with controlled band gap on Ni doping reveals their potential for use in various electronic and optical device applications. The results were discussed in detail.

Effect of Mn doping on microstructural and optical behavior of Zn(1−x)MnxO nanorod by simple auto-combustion method

Mn doped ZnO nanorods with different doping concentrations (0, 0.02, 0.05, 0.1, 0.15, and 0.2) were synthesized by simple auto-combustion method. The structural, morphological and optical behaviors of Zn(1−x)MnxO were investigated by X-ray diffraction (XRD), field-emission microscopy (FE-SEM) and diffuse reflectance spectroscopy (DRS). The structural properties of un-doped and Mn doped ZnO nanorods exhibit hexagonal wurtzite structure with no secondary phase. From scanning electron micrographs results it can be evidenced that, both crystallite size and surface morphology are significantly affected by Mn doping concentrations. From the optical studies, the reflectance in UV region of doped samples was decreased in comparison to undoped one and the optical band gap varies between 3.33 and 2.81eV. Photoluminescence spectra shows large emission band originated at 388nm and a weak band centered on 495nm. The present study reveals about the influence of Mn2+ ions on morphological and optical properties of Zn(1−x)MnxO.

Structural and optical properties of Zn1−xNixTe thin films prepared by electron beam evaporation technique

Zn1−xNixTe thin films with different composition (x=0.0, 0.05, 0.10, 0.15 and 0.20) were deposited on glass substrate by electron beam evaporation technique followed by its characterization using advanced structural and optical analysis techniques. Structural properties of the prepared thin films were studied by X-ray diffraction (XRD). The XRD patterns revealed that the binary compounds transformed into a ternary compound with cubic structure having preferred orientation along the c-direction with (111) planes. Composition analysis of the films was determined by energy dispersive analysis of X-rays (EDAX) and found to be in agreement with the precursor composition. Optical properties such as extinction coefficient (k) and band gap energy of these films were examined by using a spectroscopic ellipsometer. It was found that the extinction coefficient (k) increased with the addition of Ni content in the alloy. In comparison, the band gap energy was also determined by using transmission spectra and found to be agreed with that of the ellipsometric results. These analyses confirm that the band gap energy decreases with the increase of Ni content in the alloy.

Role of oxygen vacancies in V-doped ZnO diluted magnetic semiconductors

V-doped zinc oxide (Zn1−xVxO, 0 ≤ x ≤ 0.1) diluted magnetic semiconductors have been synthesized by using a sol–gel method. We systematically investigated effects of V-doping concentration on the structural, magnetic and optical properties of Zn1−xVxO nanoparticles. All diffraction peaks could be indexed to wurtzite structure of ZnO with V concentration of less than or equal to 3 at.%. Secondary phase of Zn3V3O8 emerged when V concentration was higher than 3 at.%. Magnetic measurements indicated that the samples with V concentration less than or equal to 3 at.% were ferromagnetic at room temperature. Saturated magnetization of Zn1−xVxO nanoparticles increased with increase of V doping concentration. The results of Raman and photoluminescence testified that the ferromagnetism in Zn1−xVxO nanoparticles was probably originated from oxygen vacancies.

Structure and optical properties of Zn0.99−xCdxMn0.01S quantum dots

Wurtzite-type Zn0.99−xCdxMn0.01S quantum dots (QDs) were synthesized facilely by the one-step solvothermal method. The as-prepared QDs had an average diameter of 4.0 ± 1.0 nm. The composition of the QDs was adjusted by controlling the Zn/Cd molar ratios. The successive shift of the XRD and PL patterns indicated that the QDs obtained were not a mixture of ZnS and CdS, but the Zn1−xCdxS solid solution. The red emission peak (coming from the cadmium vacancies), the yellow–orange emission peak (coming from the Mn2+ ions), and the green emission peak (coming from the intrinsic near band edge) were observed in the PL spectra, the intensity and position of which can be turned by controlling the Zn/Cd molar ratios effectively.