| タイトル | The Detached Bridgman Process: Application for the Growth of Low-Defect Germanium Crystals |
| 著者（英） | Curreri, Peter A.; Volz, M. P.; Dold, P.; Croell, A.; Szofran, F. R.; Schweizer, M.; Cobb, S. D. |
| 著者所属（英） | NASA Marshall Space Flight Center |
| 発行日 | 2002-01-01 |
| 言語 | eng |
| 内容記述 | During crystal growth in the vertical Bridgman process, both the melt and the growing crystal are in contact with the ampoule wall. The different thermal coefficients of expansion of the crystal and the ampoule wall can lead to stresses, crystal defects, and not rarely to cracks and/or polycrystalline growth in the crystal. The detached Bridgman process is characterized by the fact that the melt meniscus frees itself from the ampoule wall and the crystal can be grown without wall contact with the ampoule. After the effect of detachment was observed due to the reduced force of gravity during the early experiments under microgravity conditions, in the past few years the Bridgman process likewise has been successfully used to grow at least partially detached under 1g-condition. If the requirements for detaching the melt meniscus from the ampoule wall are not fulfilled by the material-specific parameters (like e.g. wetting behavior between ampoule and melt and the growth angle of the crystal), detachment can be obtained also by the imposition of suitable pressure ratios in the growth ampoule. In the context of this paper, the growth of germanium by the detached and vertical Bridgman processes in pyrolytic boron nitride crucibles will be reported, Typical gap widths between ampoule wall and detached grown crystals are approximately 10-50 microns. Compared to the crystals grown with wall contact, a reduction of the etch pit density of approximately two orders of magnitude could be obtained by growing with the detached process. |
| NASA分類 | Solid-State Physics |
| 権利 | No Copyright |
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