Electronic structure ofTiSi2

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 ${\mathrm{TiSi}}_2$. 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 $E_F$. The high residual resistivity of C49 films in comparison with those having the C54 structure (∼27 versus 0.7 μΩ 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 ($l_c$≊90 Å versus ∼990 Å for C54 ${\mathrm{TiSi}}_2$) is an extrinsic property, caused primarily by the presence of heavily faulted microstructure in the C49 films.