ABSTRACT
The approximation represented by Equation 2.1 works well for the cases of alloys with the bowing parameters smaller than 1 eV. It applies to a wide range of the elemental and compound semiconductor alloys. For example Al,Gai,As and GaAs,P,, fall into this category of alloys with the bowing parameters of 0.2 eV [4] and 0.21 eV [5], respectively. Replacing Ga with Al atom in Al Gai,As or P with As atom in GaAsxPI, introduces only a small perturbation to the crystal lattice. Consequently, the average VCA potential does not differ much from the actual potential at any lattice site, and the alloy disorder effects can be accounted for using a simple perturbation theory. This leads to only a small deviation of the energy gap from the linear interpolation between the endpoint gaps.
