STRUCTURAL EFFECTS ON THE CALCULATED SEMICONDUCTOR GAP OF CRSI2

The results of band calculations for hexagonal CrSi2, carried out in the local-density approximation, predict an indirect semiconductor gap of 0.30 eV which is in excellent agreement with the measured optical value (approximately 0.35 eV). The calculated gap, which occurs within the Cr 3d manifold, is particularly sensitive to the local Cr-Si coordination geometry. It decreases with uniaxial pressure along c and vanishes for the alternative sequencing of hexagonal-type CrSi2 layers that characterize the orthorhombic and tetragonal phases of the refractory (groups IV-VI) transition-metal disilicides.