The growth of Si single crystals from the melt and impurity incorporation mechanisms

Abstract

Growth interfaces, dislocations and impurity distributions in melt-grown crystals were observed using X-ray Lang topography, the etching method and resistivity measurements. In dislocation-free [111] growth, flat facets were observed, and the supercooling required for the growth on the facet was estimated roughly to be about 9 °C from the observed interface shapes. Dislocations intersecting the facet were found to decrease the supercooling to about 0.8 °C. This observation may suggest that dislocations provide nucleation sites even in melt growth. During [100] and [511] growth, no facets or dislocation effects were observed. The difference in growth features between the [111] and [100] growth may be explained by Jackson's theory for the structure of solid-liquid interfaces. The faceted regions were found to have higher impurity concentrations. It was observed with twin crystals, that the [511] growth has a lower K eff than the [111] growth. The observed impurity distributions seem to be explained qualitatively by considering the dependence of impurity concentration on the velocity of growth steps.