BAND-STRUCTURE CALCULATIONS OF GEXSI1-X

The band structure of Ge-Si alloy is calculated in the virtual crystal approximation using the empirical pseudopotential method which incorp orates compositional disorder as an effective potential. Various quant ities including the bowing parameter of fundamental gap, the energies of several optical gaps, and the crossover of the band gaps are calcul ated. These results are in excellent agreement with the experimental d ata. We have also calculated the variation of the bowing for the alloy Si-Ge under pressure.