The effect of doping on the gap and transport properties in FeSi: a theoretical study

Local density calculations of the electronic structures of doped FeSi are m ade by means of supercells. Pure FeSi has a semi-conducting gap of 6 mRy at 0 K. The gap decreases more or less depending on the doping clement. Isoel ectronic and non-isoelectronic substitution of Fe or Si atoms have, in gene ral, a different influence on the band structure. The gap will diminish whe n perturbations around impurity-like dopants will overlap in real space, i. e., at large doping. This effect is smaller for isoelectronic substitution. The factor of merit for optimal Peltier effect is discussed from the resul ts of the calculated thermopower and electrical conductivity. (C) 2001 Else vier Science B.V. All rights reserved.