The current paper investigates the structure of low-lifetime areas observed in a < 110 >-oriented mono-like silicon ingot grown from monocrystalline seeds. These areas are related to dislocation clusters forming at seed junctions and several generation mechanisms are discussed. Dislocations generated due to physical contact between seeds could only be completely avoided by introducing gaps between the seeds. Large gaps were, however, found to suffer from alternative generation processes not found in small gaps. Dislocations generated in the seeds and in peripheral grains does not necessarily move in to the main crystal and low-lifetime areas are mainly related to dislocations generated above the seeding structure. Dislocations are found to form clusters aligning along < 111 >-directions and are proposed to happen by glide on {111}-planes from the boundary plane between two seed crystals. The extent of low-lifetime areas and corresponding dislocation clusters, for junctions containing no or small gaps, appear to mainly depend on the misorientation between seeds and by attaining sufficiently low misorientation the high bulk lifetime can be retained also at the junctions. Analysis of the misorientations along principal axes indicates that larger misorientations can be tolerated if the misorientation is limited to a single tilt axis

The solubility of carbon in liquid silicon equilibrated with silicon carbide has been studied in the temperature region 1414-1559 C. High purity silicon was melted in graphite crucibles under Ar atmosphere with various boron additions. The equilibrium was observed to be established within minutes, after which no evolution with time could be observed. The addition of boron to the system was found to increase the carbon solubility, and an equation was derived describing the solubility as a function of both temperature and boron content. The solubility of carbon in pure liquid silicon was determined to be 65 ppm mass at the melting point of silicon. Expressions for the dissolution energy of carbon and the B-C interaction coefficient were also derived.

This paper presents a preliminary study of SiC production by use of natural gas for reduction of silica.

The solubility of nitrogen in liquid silicon equilibrated with silicon nitride and its dependence on the composition of the atmosphere has been studied in the temperature region 1428-1542 C. High purity silicon was melted in silicon nitride crucibles under Ar and N 2 atmospheres. The equilibrium was observed to be established within minutes, after which no evolution of the nitrogen content with time could be observed. The nitrogen transfer between the Si 3 N 4 -crucible and the melt was faster than the transfer via the gas-phase to such an extent that the composition of the atmosphere did not influence the solubility limit. The solubility limit as a function of temperature was found to follow:At the melting point of silicon, this equation gives the solubility of nitrogen as 42 ppm mass. From this equation, a thermodynamic derivation led to the following expression for the dissolution energy of nitrogen: