Abstract
The Cahn-Hilliard concepts are generalized and used to the description of the spinodal decomposition of A3B5 quaternary semiconductor solid solutions, when the mixing of components occurs simultaneously in the metallic and metalloid sublattices of the sphalerite structure. The resulting system of differential equations for material decomposition was used to describe the effect of composition modulation observed in the synthesis of GaxIn1-xPyAs1-y - InP heterostructures. Numerical simulation of the spinodal decomposition of the GaxIm-xPyAsuy solid solution is carried out. The intervals of the thermodynamic parameters of the technological process of the synthesis of structures, in which the effect of modulation of the composition should be manifested, are found.