Vacuum refining is a promising technique for the removal of phosphorus (P) and volatile species from silicon (Si) to provide solar grade Si for applications in solar industries. During this process an amount of Si will be lost due to unwanted evaporation. This research is the first attempt to stop the silicon loss in the course of vacuum refining process without slowing down the rate of P removal. Results indicated the application of H2 gas makes the process selective for P evaporation. Quantum chemistry calculations are done by collaboration from SINTEF in order to explain the results observed in experiments. It is shown that hydrogen has a plastic interaction with Si but not with P, leading returning the Si to melt surface, after evaporation. Outcomes of this research will contribute to engineering the vacuum refining process, in Si refining, and other metallurgical industries.

The paper is open access and can be viewed here.