Electronic Structure of TiSi sub 2

The linear augmented-plane-wave method has been applied to calculate the electronic structure and properties of the orthorhombic metastable base-centered (C49) and equilibrium face-centered (C54) phases of TiSi sub 2. Despite the structural differences, both polytypes exhibit similar electronic properties, including broad low-lying Si 3s-3p bands, partially filled Ti 3d bands, and density-of-states minima within the 3d-band manifold near E sub F. The high residual resistivity of C49 films in comparison with those having the C54 structure (-27 versus 0.7microns OMEGA cm) is analyzed with the use of the calculated Drude plasma energy and Fermi velocity for the two polytypes. It is concluded that the comparatively short scattering length of the C49 phase (l sub c ~ 90angstroms versus ~99angstroms for C54 TiSi sub 2) is an extrinsic property, caused primarily by the presence of heavily-faulted microstructure in the C49 films.