研究目的
Investigating the influence of different melt streams on the distribution of phosphorus in multi-crystalline silicon ingot using travelling magnetic fields (TMF) to alter axial phosphorus profiles.
研究成果
The application of enhanced melt stirring by TMF for G1 ingots might result in additional phosphorus evaporation during solidification step, since crystallization time is considerably longer and the ratio of melt surface to its volume is somehow larger. This effect is expected to be pronounced, provided that homogenization time is reduced and TMF is applied only after solidification has started.
研究不足
The construction of gas inlet/outlet minimizes the possibility of phosphorus evaporated from one crucible to be transported to other crucibles, but it cannot be definitely asserted that cross-influence of melts on each other was fully eliminated. The size of G0 ingots is considerably smaller than that for G1, which makes it difficult to maintain steady solidification in a G1-size furnace, particularly at the end of it.
1：Experimental Design and Method Selection:
Directional solidification of mc-Si was realized in a G1-size furnace equipped with KristMAG?-heater magnet module. A new rectangular setup was developed for simultaneous directional solidification of 4 G0-sized mc-Si ingots under TMF influence.
2：Sample Selection and Data Sources:
High purity silicon feedstock with resistivity greater than 1000 Ωcm was used for every ingot charge. Ingots were doped with highly phosphorous-doped silicon.
3：List of Experimental Equipment and Materials:
G1-size furnace, KristMAG?-heater magnet module, rectangular crucibles made of high purity fused silica, Si3N4 coating.
4：Experimental Procedures and Operational Workflow:
After all feedstock in crucibles was molten, a TMF was applied and kept constant during the whole process of melt homogenization and ingot growth.
5：Data Analysis Methods:
Resistivity was measured by 4-point probe method along the central and side vertical axes on as-cut ingot surface. FTIR method was applied to measure the distribution of interstitial oxygen.
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