Fluorescence EXAFS study of residual Ga in β-FeSi2grown from Ga solvent

Solution growth method is a suitable growth technique to obtain a large-sized and good crystalline quality β-FeSi2 single crystal. However, during the solution growth method, solvent atoms are often automatically doped into the growing crystals and may affect properties of them. In this work, we investigated Ga atoms in β-FeSi2 grown from a Ga solvent by EXAFS and discussed the effect of the Ga atoms on electrical properties of β-FeSi2. The results of the EXAFS measurement indicated that 60% of Ga in β-FeSi2 substituted Si sites, and 40% of them substituted Fe sites. The ab-initio calculation of electron density of states indicated that when the concentration of Ga in β-FeSi2 is so high as 1.0at%, the residual Ga is not the origin of the p-type conductivity of the β-FeSi2 crystal grown from the Ga solvent. We should conduct further calculation to decide if the residual Ga is the origin of the p-type conductivity or not in the real β-FeSi2 crystal with only 0.1at% of Ga.