THE EFFECT OF THE VIOLATION OF VEGARD LAW ON THE OPTICAL BOWING IN SI1-XGEX ALLOYS

The effect of the deviation of the lattice parameters from Vegard's ru le on the optical bowing of the fundamental gap in Si1-xGex semiconduc tor alloys is discussed. Our computations are based on the pseudopoten tial method. To make allowance for the chemical disorder, the virtual- crystal approximation is used, including a correction to the alloy pot ential. Our results show that the bowing parameter is highly improved when the lattice relaxation effect is included which indicates the imp ortance of the lattice mismatch in the electronic band structure calcu lations of IV-IV semiconductor alloys. (C) Published by Elsevier Scien ce B.V.