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Constitutional Supercooling in Czochralski Growth οf Heavily Doped Silicon Crystals

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Friedrich J., Stockmeier L., Müller G.

Acta Physica Polonica A

2013

vol. 124

issue 2

219-226

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.

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76%

Sack M., Attmann F., Stängle R., Wolf A., Frey W., Müller G.

Acta Physica Polonica A

2009

vol. 115

issue 6

1081-1083

For the production of synthetic bio-fuel the use of green biomass enables additional resources of raw material supplementary to the commonly used dry material. An electroporation assisted drying process gives the opportunity of a more efficient dewatering than only pressing and subsequent drying. Experiments showed a lower relative humidity of the pressed material after electroporation compared to pressing the raw material only. Moreover, the drying process of the electroporated material was much shorter. This is because the pores formed in the cell membranes foster a better extraction of water during pressing and enhance the diffusion process during the drying process. The paper presents exemplarily the experimental results for green rye. For the electroporation-assisted drying process the electric contact to the plant material has to be established by means of the juice inside the plants only rather than adding additional water. Hence, for experiments in larger scale, the existing electroporation device KEA-MOBIL has been equipped with a new combined electroporation reactor and press. The reactor has a plate electrode system, whose upper electrode additionally serves as a piston to apply mechanical force to extract juice for a good electrical contact between plant material and the electrodes. A two-stage Marx generator serves as a pulse source. To reduce the insulation distance to the walls of the shielding cabin the Marx generator is operated in ground symmetric configuration. The device has been designed for a batch-wise throughput of 50 kg/h. An automatic feeding device enables the alternating use of two test vessels. The device has been tested on-site on a farm with green rye and grass.

Magnetic Textures in Thin Ion-Irradiated Ni and Fe Films

76%

Lieb K., Zhang K., Müller G., Schaaf P., Uhrmacher M., Felsch W., Münzenberg M.

Acta Physica Polonica A

2001

vol. 100

issue 5

751-760

Heavy-ion bombardment of thin ferromagnetic, polycrystalline films can induce substantial changes of their magnetic and microstructural properties. Since we first identified this effect in 50-150 nm thick Fe and Ni films irradiated with Xe-ions, we made a systematic search for the influence of various film and implantation parameters on the orientation and degree of the magnetic anisotropy and how these parameters correlate with the microstructure of the films. Several analyzing methods, such as Rutherford backscattering, magneto-optical Kerr effect, X-ray diffraction, magnetic force microscopy, ^{111}In perturbed angular correlation, and conversion electron Mössbauer spectroscopy, were employed in the investigation.

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3 Acta Physica Polonica A

1 2013

1 2009

1 2001

3 Müller G.

1 Attmann F.

1 Felsch W.

1 Frey W.

1 Friedrich J.

1 Lieb K.

1 Münzenberg M.

1 Sack M.

1 Schaaf P.

1 Stockmeier L.

1 Stängle R.

1 Uhrmacher M.

1 Wolf A.

1 Zhang K.

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Constitutional Supercooling in Czochralski Growth οf Heavily Doped Silicon Crystals

Upgrade of the Electroporation Device KEA-MOBIL

Magnetic Textures in Thin Ion-Irradiated Ni and Fe Films