SI1-X-YGEXCY ALLOY BAND STRUCTURES BY LINEAR COMBINATION OF ATOMIC ORBITALS

We have applied a virtual crystal approximation to the linear combinat ion of atomic orbitals method to calculate critical point energies of unstrained Si1-x-yGexCy alloys spanning the composition parameter spac e. Additionally, we have calculated the band structure across the Bril louin zone for a series of alloy compositions. We found the band energ ies had significant bowing departures from linearity throughout the sy stem. In some cases, the energy band gap was not monotonically depende nt on composition. Our theoretical results are compared with recent ex perimental results, and good agreement was found overall. (C) 1997 Ame rican Institute of Physics.