Crystal growth considerations in the use of “solar grade” silicon

Macrosegregation of Impurities in Directionally Solidified Silicon

“…[12] # From Narushima et al [13] : presented a range of segregation coefficients for O and C reported by different authors. **From Nozaki et al [14] From Hopkins et al [15] : The segregation coefficients were referred to as effective coefficients, which might be equal to or larger than the actual equilibrium coefficients. àà From Kobayashi.…”

“…In Table I, the equilibrium segregation coefficient and the solubility of several impurities in solid Si (considering the equilibrium with solid precipitates) are shown. [8][9][10][11][12][13][14][15][16][17] If the Si-impurity binary phase diagram is available, this solubility is usually the maximum concentration at the solvus line. Because of macrosegregation, the initial part of the solidified ingot is much purer than the remaining ingot, indicating a refining of the feedstock composition.…”

LSA large area silicon sheet task continuous Czochralski process development. Final report

“…Six sources were identified as potential oxide contributors: (1) puller leaks, (2) oxide evaporation from the primary melt surface, (3) water leaks, (4) surface oxide from the granular silicon feed, (5) premelter fused quartz liner-graphite reaction, and (6) fused quartz heat shield-graphite reaction. Whatever the oxide source, it will collect on any relatively cool surface and the premelter watercooled electrodes were very convenient in this regard.…”

Silicon Sheet Growth Development of the Large Area Silicon Sheet Task of the Low Cost Silicon Solar Array Project Fifth Quarterly Progress Report, October 1-December 31, 1978

“…The program plan (Figure 1) for design and construction of the growth facility is nearly complete. Remaining unfinished portions ?f the program are (1) melt level control via weight and (2) the lump recharge device.…”