Development of Quantifiable Heat Transport Control for Crystal Growth and Segregation in Ezochralski Geometry: Doped Germanium

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9221156 Witt Semiconductor bulk crystal growth suffers from a gap between theory and experiment which is to a large extent attributable to the non-availability of quantifiable thermal boundary conditions. With focus on this deficiency it is proposed to design, construct, characterize and test a heat- pipe-based heat transfer control system for semiconductor crystal growth by the Czochralski technique. The system will involve a three part heat pipe assembly with sodium as heat transfer fluid. The establishment of controllable and quantifiable axi-symmetric thermal boundary conditions is to be ascertained through temperature measurements with a thermocouple array and on the basis of thermal imaging. Its functionality is to be tested in growth of Ga doped germanium at crystal diameters of up to 2 cm. The relationship between the prevailing boundary conditions and the crystal growth behavior is to be determined through quantitative segregation analyses. These analyses are made possible with the introduction during growth of current controlled crystal melt interface demarcation (revealed by etching and phase contrast microscopy on axial crystal samples) and quantitative composition determination based on spreading resistance measurements. %%% Semiconductor crystal growth, the basis for solid state device technology, is conducted on a largely empirical basis and the resulting materials fall short of theoretical performance limits. The proposed research is expected to contribute to narrowing the gap between theory and experiment. It will provide a means for increased control over growth related defect formation in semiconductors and is expected to establish a basis for more effective use of mathematical modeling to achieve specific growth control objectives. ***