Optical Properties Of Mg Research Articles

Growth and optical properties of Mg:Ce:Fe:LiNbO 3 crystals

The congruent Ce(0.1 mol%):Fe(0.03 wt.%):LiNbO 3 crystals doped with different concentrations of 2.0 mol%, 4.0 mol% and 6.0 mol% MgO were grown by the Czochralski method. The Curie temperature and absorption spectra were measured to analyze their structure. The photorefractive properties of the Mg:Ce:Fe:LiNbO 3 crystals were experimentally studied by using two-beam coupling. The results of the two-wave coupling experiments showed that as the doping concentration of Mg increased, the diffraction efficiency decreased, but the response time and photorefractive sensitivity increased. Among all samples, the dynamic range of the Mg(4 mol%):Ce:Fe:LiNbO 3 crystal is the largest (3.18).

Growth and optical properties of Mg, Fe Co-doped LiTaO 3 crystal

Mg, Fe double-doped LiTaO 3 and LiNbO 3 crystals have been grown by Czochralski method. The optical properties were measured by two-beam coupling experiments and transmitted facula distortion method. The results showed that the photorefractive response speed of Mg:Fe:LiTaO 3 was about three times faster than that of Fe:LiTaO 3, whereas the photo-damage resistance was two orders of magnitude higher than that of Fe:LiTaO 3. In this paper, site occupation mechanism of impurities was also discussed to explain the high photo-damage resistance and fast response speed in Mg:Fe:LiTaO 3 crystal.

Double layer formation in Mg–TM switchable mirrors (TM: Ni, Co, Fe)

The optical properties of Mg–TM (TM: Ni, Co, Fe; Mg:TM ≈ 2) thin films during hydrogenation are investigated using reflection and transmission measurements. Mg–Ni and Mg–Co show an unusual behavior upon exposure to hydrogen. The nucleation of the hydride starts at the film substrate interface and not – as intuitively expected – at the Pd covered top side of the film. Consequently, a double layer structure is formed. Reflection measurements are used to identify the loading behavior as the double layering yields to an remarkable optical black state at intermediate hydrogen concentrations. Photometric measurements on samples loaded at H 2-pressures of 10 5 Pa show that in Mg–NiH x and Mg–CoH x the complex hydrides Mg 2NiH 4 and Mg 2CoH 5 are formed, whereas in Mg–Fe x the formation of MgH 2 is prevalent.

Effect of annealing temperature on properties of Mg xZn 1−xO thin films deposited by RF magnetron sputtering

Mg x Zn 1− x O films ( x = 0.16 ) have been prepared on silicon and sapphire substrates by radio frequency (RF) magnetron sputtering. The effects of annealing temperature on the structure, morphology and optical properties of Mg x Zn 1− x O films are studied using XRD, AFM, photoluminescence and the transmittance spectra. The results indicate that the thin films have hexagonal wurtzite single-phase structure of ZnO, a preferred orientation with the c-axis perpendicular to the substrates, and with increasing annealing temperature the intensities of the (0 0 2) peaks for the XRD, grain sizes and intensities of the UV photoluminescence peaks increase while the FWHM of (002) peaks decrease, which demonstrate that the high quality of Mg x Zn 1− x O films deposited by RF magnetron sputtering can be obtained by controlling annealing temperature.

Structural and optical properties of Mg x Zn 1–x O thin films formed by sol–gel method

MgxZn1–xO thin film alloys were formed on Si substrates by a sol–gel method. The percentage of Mg was controlled by the mol ratio in the starting alcoholate sol solution. The structure of films was studied by X-ray diffraction (XRD). The grain morphology and their spatial compositions were measured by scanning electron microscopy (SEM) together with energy dispersive X-ray spectrometry (EDS) analysis. The films were found to be composed of grains of around several ten nanometers in size and different Mg contents. The photoluminescence (PL) shows a bandedge emission with its peak energy changing from 3.3 eV to 3.6 eV for the Mg content of the starting alcoholate solution from 0% to 20%. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural and optical properties of Mg xZn 1− xO thin films grown by metal-organic chemical vapor deposition

High-quality Mg x Zn 1− x O thin films were successfully grown on c-plane sapphire substrates by metal-organic chemical vapor deposition. The c-axis oriented Mg x Zn 1− x O films were deposited on sapphire at the temperature of 600–630°C. The structural and optical properties of Mg x Zn 1− x O films were investigated using X-ray diffraction (XRD) and the transmittance spectrum. MgO phase separation was not observed with Mg content up to x=0.39. The optical band gaps of Mg x Zn 1− x O alloys (0⩽ x⩽0.39) range from 3.3 to 3.95 eV.

Influence of structural defects on the optical properties of Mg:LiNbO3 single crystals

A comparative analysis of the dependences of the refractive index of Mg:LiNbO3 single crystals on the Mg concentration is performed in the visible and IR transparency regions. The results of measurements at the wavelengths above 4 μm suggest the four-step mechanism of incorporation of the Mg impurity to the LiNbO3 crystal in the range of molar concentrations of Mg from 0 to 7.1 %. The resonances observed between 1 and 2 μm and between 2.8 and 3.5 μm in the transparency region are interpreted as contributions from polaron states. It is shown that the resonance in the region between 1 and 2 μm is strongly enhanced in crystals with the molar concentration of Mg above 5.1%.

Incorporation and optical properties of magnesium in cubic GaN epilayers grown by molecular beam epitaxy

The incorporation and optical properties of Mg in cubic GaN (c-GaN) epilayers grown by rf plasma-assisted molecular beam epitaxy on (100) GaAs are investigated by secondary ion mass spectroscopy and low-temperature photoluminescence (PL). By varying the Mg flux by more than four orders of magnitude, the incorporation of Mg saturates at high Mg flux and is limited to a value of about 5×1018 cm−3 due to the high volatility of Mg at growth temperature. In addition, we observe an accumulation of Mg at the GaN/GaAs interface due to a diffusion of Mg to the GaAs substrate. Low-temperature PL spectra reveal several well-separated lines. Besides a shallow acceptor level at EA≅0.230 eV, additional Mg-related deep defect levels indicate an incorporation of Mg at off-gallium sites or as complexes.

Non-empirical core-polarization effects on the optical properties of Mg(I): II. Bound - bound and bound - free one- and two-photon transitions up to the third ionization threshold

The optical properties of Mg(I) have been computed using a CI approach in which the multi-electron basis includes single and double excitations from the M shell plus single excitations from the Ne-like core. The orbital set is of type and comprises STO, hydrogenic plus spatial oscillating STOCOS functions. The continuum states have been obtained by solving a discretized integral equation for the K-matrix half on the energy shell. Oscillator strengths and radiative lifetimes for the discrete states of the , and manifolds have been computed together with one- and two-photon cross sections of the ground and the states evaluated in the LOPT approximation. The maximum energies reached were 0.005 au and 0.035 au below the 4s ionization threshold for one- and two-photon processes, respectively. All the quantities have been determined in both the velocity and the length gauge.

Non-empirical core polarization effects on the optical properties of Mg(I): I. Discrete and continuum energy spectrum up to the third ionization threshold

The optical properties of Mg(I) have been computed using a configuration-interaction (CI) approach in which the multielectron basis includes single and double excitations from the M shell plus single excitations from the Ne-like core. The orbital set is of type and comprises STO, hydrogenic plus spatial oscillating STOCOS functions. The continuum states have been obtained by solving a discretized integral equation for the K matrix half-on-the-energy shell. For the , , and manifolds we have computed the discrete and autoionizing levels of the 3s nl, 3p nl, 4s nl and 3d nl series, the last two lying beyond the 3p ionization threshold.

Optical properties of Mg, from UV to IR, using ellipsometry and reflectometry

Magnesium films have been traditionally used for UV filters. However, scarce information has been reported on its optical properties [1–3] and the problems it presents in the production of the films. Being a Drude material, magnesium is a suitable material for studying the photon-surface plasmon interaction by attenuated total reflectance, but the dielectric function is poorly known for the IR-visible region. In this paper we present our values for the optical properties of a Mg thin film obtained from ellipsometric and absolute reflectance measurements. The dielectric function is estimated using Drude modeling, extending the previously reported data into the infrared.

Photoluminescence and optical properties of Mg x Zn1−x Te alloys

The photoluminescence and optical properties of MgxZn1−xTe alloys have been studied in the composition range 0<x<0.48. The results are discussed taking into account the formation of band tails due to the alloying effect or random distribution of impurities. The role of residual defects in magnesium-rich alloys is emphasized. On the other hand, a preliminary investigation showed that it is possible to incorporate lithium by high-temperature diffusion in MgxZn1−xTe alloys without altering the magnitude or the homogeneity of the magnesium concentration. Evidence is obtained for an increased quantum efficiency after lithium doping.

Electrical and optical properties of Mg-, Ca-, and Zn-doped InP crystals grown by the synthesis, solute diffusion technique

p-type InP crystals doped with Mg, Ca, and Zn have been grown by the synthesis, solute diffusion (SSD) technique. Distribution coefficients for the Mg and Ca in the SSD-grown InP were determined to be 0.20 and 0.025, respectively. 4.2 K photoluminescence emission peaks have also been investigated for Mg-, Ca-, and Zn-doped samples. The binding energy is determined to be EA (Mg)=40 meV, EA (Ca)=43 meV, and EA (Zn)=47 meV. Comparison of the emission peak energies between impurity-doped and nominally-undoped InP shows that Mg and Ca as well as Zn are incorporated as residual shallow acceptors in the high-purity SSD-grown InP (ND−NA ≤1015 cm−3 at 300 K).