Abstract
The compositional dependences of long‐ and short‐wavelength critical point phonons in mixed zincblende semiconductors are studied within the framework of an interpolation scheme between the end‐member compound phonons which is founded by an “averaged Green's function” technique. The derived dependences on composition agree with those expected from a model with three virtual atoms per unit‐cell (pseudo‐unit cell model). Explicit results are presented for the compositional dependences of the Γ, X, and L point phonons in In1−xGaxP and Gap1−xAsx and compared with experimentally derived phonon frequencies.