A REVIEW OF MEASUREMENT OF THERMOPHYSICAL PROPERTIES OF SILICON MELT

Measurements of thermophysical properties of Si melt and supplementary study of X-ray scattering/diffraction by the authors' group were revi ewed. The values obtained differed variously from those of literature. Density was 2-3% larger, surface tension 20-30% smaller, viscosity up to 40% larger, electrical conductivity 8% smaller, spectral emissivit y more or less in good agreement with literature values, and thermal d iffusivity a few percent larger. An anomalous density jump was found n ear the melting point. Surface tension and viscosity also showed anoma ly. A strange time-dependent change of density was observed over 3 h a fter melting. X-ray analyses suggested a slight change in local atom o rdering, but showed no sign of cluster formation. An addition of 0.1 a t% gallium caused the density jump to disappear, while that of boron c aused no change. An EXAFS study of the former melt indicated a strong interaction between Ga and Si atoms as if molecules of GaSi3 existed. The implications of the measured properties are a possibility of soft- turbulence in an Si melt in a relatively large crucible, a more compli cated manner of intake of oxygen depleted molten Si from the free surf ace region to underneath the growing crystal, and a relaxation of the melt after melting arising from trapped gas species.