ИСТИНА

Developing the effective methods of refining processes of metallurgical silicon to produce solar-grade silicon allowing the creation of photoelectric transducers at low-cost is crucial. It is important to note that metal impurity concentrations in solar-grade silicon materials are several orders of magnitudes higher than concentrations in micro-electronic-grade silicon materials and depend on the form the impurities existing in. Therefore to increase resources of up-to-date technologies and to develop new methods of metallurgical silicon refining the correct data on the impurities forms are required at various temperatures and chemical compositions. This information is necessary to choose the refining technology and to control the material quality. To solve the formulated problem analysis of impurities forms has been carried out for most widespread impurities Al, Mn, Fe, Ni, Ti, O, which are of significant interest. Thermodynamic evaluation of the properties of solid silicon based solutions has been used as well as available data on thermodynamic properties of crystalline compounds that may form as a result of interactions impurity-silicon and impurity-impurity. In addition, segregation coefficients of transition metals between solid silicon based solution and liquid aluminum and solid phosphorus have been estimated, which are used for creation of the required conductivity type of material.