Abstract
The effects of boron and arsenic doping in beta-FeSi2 have been studied by theoretical simulations and electrical characterization. First-principles calculations revealed that B and As were energetically favorable to occupy the Si-II and Si-I sites, respectively. The impurity doping was found to induce structural relaxation via lattice distortion, with As doping causing elongation of the As-Si bonds and contraction of the As-Fe bonds while B doping resulting in both inward and outward relaxations of the neighboring Si and Fe host atoms. p-type and n-type conductivities were suggested for the B- and As-doped beta-FeSi2, respectively, and confirmed experimentally by Hall effect measurements. B and As were shown to introduce shallow impurity levels in the forbidden gap of beta-FeSi2 and therefore could be effective dopants for beta-FeSi2. A carrier concentration in a tunable range of 10(17) cm(-3) and a mobility in the order of 100 cm(2)/V s were consistently obtained. c 2009 American Institute of Physics. [DOI:10.1063/1.3176944]