Determination of boron and hydrogen in materials for multicrystalline solar cell production with prompt gamma activation analysis

For the optimization of the manufacturing process of multicrystalline silicon (mc-Si) for solar cells in order to reduce energy consumption and costs, it is important to know the distribution of the impurities. In our project, we analyzed the raw materials, the crucibles, and the solidified blocks (ingots) with different methods based on neutron activation. In this paper, we present the technique and the results of the boron and hydrogen determination with prompt gamma activation analysis (PGAA). We show that the distribution of boron in the ingots can be successfully described with a Scheil curve. Concerning the raw material, the most relevant information is the average elemental mass fraction. For this purpose, PGAA is well suited since it provides a bulk analysis with detection limits down to the low ng/g range for boron and A mu g/g range for hydrogen. In this context, the hydrogen content of fluidized bed reactor (FBR) feedstock is discussed in detail. These were the first extensive PGAA studies of the boron and hydrogen content in mc-Si.