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Czochralski Technique (czochralski + technique)
Selected AbstractsDefect structure and spectroscopic characteristics of codoped Hf: Er: LiNbO3 crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2009Liang Sun Abstract Codoped Hf: Er: LiNbO3 crystals have been grown by the Czochralski technique. Defect structures of the crystals were analyzed by IR absorption spectra, and the compositions of the crystals were measured by X-ray fluorescent spectrograph. A new OH, -associated vibrational peak at 3492 cm,1 was revealed in 6 mol % Hf: 1 mol % Er: LiNbO3 crystal. It was attributed to (HfNb), -OH, -(ErNb)2, defect centers. The Er3+ concentrations in crystals gradually decreased with the increase of the codoped Hf4+ concentrations in the melts. The emission characteristics of the crystals were investigated by the fluorescence spectrum. It was found that the luminescent intensity in codoped 6 mol % Hf: 1 mol % Er: LiNbO3 crystal was 3.5 times stronger than that in single doped 1 mol % Er: LiNbO3 crystal. The luminescent enhancement effect was successfully explained on the basis of defect structure of the crystals. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of Mg/Er co-doping on the principal laser parameters of LiNbO3 crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2007Liang Sun Abstract Mg: Er: LiNbO3 crystals were grown by the Czochralski technique with various concentrations of MgO = 2 mol%, 4 mol%, 6 mol% and the fixed concentration of Er2O3= 1 mol% in the melt, and the 8 mol%Mg: 1 mol%Er: LiNbO3 crystal was fabricated by the Czochralski technique with special technology process. The crystals were treated by polarization, reduction and oxidation. The segregation coefficients of Mg2+ and Er3+ in Mg: Er: LiNbO3 crystals were measured by X-ray fluorescence spectrograph, as well as the crystal's defect structure and optical properties were analyzed by the UV-Vis, IR and fluorescent spectroscopy. The pump wavelength and the surge wavelength were determined. Using m-line method tested optical damage resistance of those crystals, the results show that photodamage threshold of Mg: Er: LiNbO3 crystals are higher than that of Er: LiNbO3 crystal, and the oxidation treat could enhance the photodamage resistant ability of crystals while the reduction treat could depress the ability. The optical damage resistance of 8 mol%Mg: 1 mol%Er: LiNbO3 crystal was the strongest among the samples, which was two orders magnitude higher than that of 1 mol%Er: LiNbO3 crystal. The dependence of the optical properties on defect structure of Mg: Er: LiNbO3 crystals was discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Inhomogeneity of composition in near-stoichiometric LiNbO3 single crystal grown from Li rich meltCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2006L. Gao Abstract A near-stoichiometric LiNbO3 single crystal has been grown by the Czochralski technique from a melt of 58.5 mol% Li2O. Its composition homogeneity was assessed by measuring the UV absorption edge. It was found that the maximum composition difference is about 0.03 mol% in the radial direction and 0.05 mol% in the axial direction. Differential scanning calorimetry (DSC) analysis was performed on the powder from the synthesized raw material and the frozen melt after crystal growth. The analytical results indicate that, during crystal growth, the magnitude of lithium volatilization from the melt surface is more than the degree of segregation from the crystal. The volatilized lithium diffuses into the crystal to compensate for the lithium segregation in the LiNbO3 crystal. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation of semi-insulating InP co-doped with Ti and various acceptors for use in X-ray detectionCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4-5 2005K. Zdansky Abstract Semi-insulating InP single crystals co-doped with Zn and Ti and co-doped with Ti and Mn were grown by Czochralski technique. Wafers of these crystals were annealed for a long time at a high temperature and cooled slowly. The samples were characterized by temperature dependent resistivity and Hall coefficient measurements. The binding energies of Ti in semi-insulating InP co-doped with Ti and Zn and co-doped with Ti and Mn were found to differ which shows that Ti may occupy different sites in InP. The curves of Hall coefficient vs. reciprocal temperature deviate from straight lines at low temperatures due to electron and hole mixed conductance. The value of resistivity of the annealed semi-insulating InP co-doped with Ti and Mn reaches high resistivity at a reduced temperature easily achievable by thermo-electric devices which could make this material useable in X-ray detection. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of trivalent ions doped PbWO4 crystals and their scintillation propertiesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2004C. H. Yang Abstract Undoped and series of trivalent ions(including La, Y, Gd and Tb) doped PWO crystals were grown from 5N raw materials by using Czochralski technique. Trivalent ions doping improved the transmittance, fast components of luminescence and radiation damage resistance for compensating structure defects. Corresponding, the fraction of light yield at shorter collecting time was increased. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synchrotron X-ray topography of electronic materialsJOURNAL OF SYNCHROTRON RADIATION, Issue 3 2002T. Tuomi Large-area transmission, transmission section, large-area back-reflection, back-reflection section and grazing-incidence topography are the geometries used when recording high-resolution X-ray diffraction images with synchrotron radiation from a bending magnet, a wiggler or an undulator of an electron or a positron storage ring. Defect contrast can be kinematical, dynamical or orientational even in the topographs recorded on the same film at the same time. In this review article limited to static topography experiments, examples of defect studies on electronic materials cover the range from voids and precipitates in almost perfect float-zone and Czochralski silicon, dislocations in gallium arsenide grown by the liquid-encapsulated Czochralski technique, the vapour-pressure controlled Czochralski technique and the vertical-gradient freeze technique, stacking faults and micropipes in silicon carbide to misfit dislocations in epitaxic heterostructures. It is shown how synchrotron X-ray topographs of epitaxic laterally overgrown gallium arsenide layer structures are successfully explained by orientational contrast. [source] Cover Picture: Laser Phys.LASER PHYSICS LETTERS, Issue 7 2010Lett. It's known that single crystals of germanate melilites, such as Ba2ZnGe2O7 and Sr2MgGe2O7, show a congruent melting behavior at about 1450 °C. Crystals of Sr2MgGe2O7 were grown from melt of stoichiometric composition by the Czochralski technique using a seed crystal orientation (and pulling direction) along [001], a pulling velocity of 2,3 mm/h and crystal rotation of 40,60 rad/min. For single crystal growth of Ba2ZnGe2O7 a melt with a surplus of ,4 wt.% BaO and ,5 wt.% GeO2 proved to be useful. Grown crystals are of dimensions up to 25 mm in length and 18 mm in diameter for Sr2MgGe2O7 and of up to 15 mm in length and in diameter for Ba2ZnGe2O7. In Cover picture an example of a grown crystal of Sr2MgGe2O7 is presented. (Cover picture: A.A. Kaminskii, L. Bohatý, et al., pp. 528,543, in this issue) (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Crystal growth, optical properties, and continuous-wave laser operation of Nd3+ -doped CaNb2O6 crystalLASER PHYSICS LETTERS, Issue 10 2009Y. Cheng Abstract Laser crystal Nd:CaNb2O6 with excellent quality has been grown by Czochralski technique. The effective segregation coefficient of Nd3+ was studied by X-ray fluorescence method. The polarized absorption spectra and the fluorescence spectra of Nd:CaNb2O6 were measured at room temperature. The peak absorption cross section was calculated to be 6.202×10,20 cm2with a broad FWHM of 7 nm at 808 nm for E , a light polarization. The emission cross section at 1062 nm is 9.87 × 10,20 cm2. We report what we believe to be the first demonstration of the continuous-wave Nd:CaNb2O6 laser operation under diode pumping. Output power of 1.86 W at 1062 nm was obtained with a slope efficiency of 19% in the CW regime. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] | ||||||||||