Structure and Properties of Metallurgical-grade Silicon

The main raw material for the production of solar-grade silicon used in the production of photovoltaic energy converters for solar cells is metallurgical silicon. When choosing any technology for the production of solar-grade silicon, special attention should be given to improving the quality of the initial MG-Si. The aim of this work was to study the structure and properties of metallurgical silicon. Samples of MG-Si were prepared in laboratory conditions. Samples, obtained by plasma-arc melting in the furnace with graphite electrodes, contained admissible impurity limits. The structure and physico-mechanical properties of MG-Si with different content of impurities were studied in a wide range. The electrical resistivity index depended on the presence of grain boundaries and the level of impurity elements content, as well as the presence of carbides and silicides. At the maximum grain size of 105.58 μm, the maximum value of the electrical resistivity of 2.65 Ohm⋅cm was observed. The size and shape of the grains also had an effect on mechanical properties. Selection of the optimal composition of all components, as well as the conditions of the melting, allowed to achieve a defect-free structure. Such MG-Si samples can be used for various practical applications.