Electronic structure of the Nowotny chimney-ladder silicide Ru2Si3

We report ab initio calculations for the electronic structure of the Nowotny chimney-ladder silicide Ru2Si3 in the orthorhombic low-temperature phase. We find Ru2Si3 to be a semiconductor with a direct band gap of about 0.45 eV. Since this gap is a p-d gap, the oscillator strength for a direct transition is expected to be of sizable magnitude. Also, the calculated effective masses of hole and electron states suggest that Ru2Si3 is a very promising material for various applications in semiconductor technology. The electronic structure is controlled by the hybridization of Si p states with Ru d states and shows similarities to the group-IV transition-metal disilicides (CrSi2, MoSi2, WSi2) and to transition-metal-rich silicides. The calculations are based on the density-functional theory in local-density approximation and are performed by means of the full-potential linearized-augmented-plane-wave method.