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1

Constitutional Supercooling in Czochralski Growth οf Heavily Doped Silicon Crystals

100%

Friedrich J., Stockmeier L., Müller G.

Acta Physica Polonica A

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2013

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vol. 124

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issue 2

219-226

EN

This study analyses the phenomenon of constitutional supercooling, which is one of the major problems in industrial growth of heavily doped (>10^{20} atoms/cm^3) silicon crystals by the Czochralski technique. The systematic study is based on theoretical models and experimental data considering the effect of three important dopants (B, P, and As) in dependence of the relevant growth parameters for the Czochralski process. Based on these results, conclusions will be drawn for the stability limits of the Czochralski growth of dislocation-free heavily doped silicon crystals in dependence of the doping species and their concentration.

2

Electronic and Magnetic Effects on Cu Doping Ti_2NiAl Heusler Alloy: A First-Principles Study

100%

Wei X., Chu Y., Sun X., E Y., Song T., Guo P.

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vol. 126

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issue 3

795-798

EN

We investigate the effect of the electronic and magnetic properties on nonmagnetic Cu-3d atoms doping the Heusler alloy Ti_2Ni_{1-x}Cu_xAl (0 ≤ x ≤ 1) using first-principles calculations. The optimized lattice constants are consistent with the Vegard law, and energies of doped systems become more lower as the increase of x concentration. A critical transition diagram from half-metallic to metallic characters is discussed. In addition, the magnetic interactions between p and d states are illustrated. Finally, magnetic moments are given as a function of x value, which implies that the Slater-Pauling rule is obeyed at low Cu content (x ≤ 0.2).

3

Comparative Study between Energy Levels of Cr^{3+} and Co^{2+} Ions Doped in MgF_{2} Crystal

100%

Nistora R., Andreici L., Avram N.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

538-540

EN

The aim of this paper is to present a comparison of the energy level schemes of Cr^{3+} (3d^{3} electrons) and Co^{2+} (3d^{7} electrons), each of ions doped, separately, in MgF_{2} crystal. We report on the detailed and consistent crystal field analysis of Cr^{3+} spectra in MgF_{2} crystal and compare with results, previously obtained, for Co^{2+}, doped in same host matrix. The results are based on application of the exchange charge model of crystal field to the calculation of crystal field parameters and energy levels of both ions doped in MgF_{2}.The calculations have been performed on previously optimized geometry of MgF_{2} crystal. The obtained results are compared with experimental data and discussed.

4

Ion and Electron Beam Induced Luminescence οf Rare Earth Doped YAG Crystals

45%

Gawlik G., Sarnecki J., Jóźwik I., Jagielski J., Pawłowska M.

Acta Physica Polonica A

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2011

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vol. 120

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issue 1

181-183

EN

The aim of this work was the evaluation of ion-beam induced luminescence for the characterization of luminescent oxide materials containing rare earth elements. The yttrium aluminium garnet epilayers doped with Nd, Pr, Ho, and Tm atoms were used. The ion-beam induced luminescence spectra were excited using 100 keV H_2^{+} ion beam and were recorded in the wavelengths ranging from 300 nm up to 1000 nm. The separate parts of the surface of the same samples were used for ion-beam induced luminescence and cathodoluminescence experiments. Cathodoluminescence spectra have been recorded in the range from 370 nm up to 850 nm at 20 keV e-beam in scanning electron microscope equipped with a grating spectrometer coupled with a photomultiplier. The observed narrow ion-beam induced luminescence lines can be ascribed to the well known radiative transitions in the rare-earth ions in the YAG crystals. The cathodoluminescence spectra reveal essentially the same emission lines as ion-beam induced luminescence. The decrease of the ion-beam induced luminescence lines intensity has been observed under the increasing ion fluences. The ion-beam induced luminescence may be used for characterization of transparent luminescent materials as an alternative method for cathodoluminescence and can be especially useful for observation of ion-beam damage formation in crystals.

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Constitutional Supercooling in Czochralski Growth οf Heavily Doped Silicon Crystals

Electronic and Magnetic Effects on Cu Doping Ti_2NiAl Heusler Alloy: A First-Principles Study

Comparative Study between Energy Levels of Cr^{3+} and Co^{2+} Ions Doped in MgF_{2} Crystal

Ion and Electron Beam Induced Luminescence οf Rare Earth Doped YAG Crystals