Composition correlations in ternary semiconductor alloys

Abstract

Spatial composition fluctuations in semiconductor alloys $A_x{B}_{1-x}C$ involve elastic energy when the lattice parameters of $\mathrm{AC}$ and $\mathrm{BC}$ differ. Therefore, the fluctuations are expected to be reduced below those exhibited by a purely random distribution of the constituent ions. We estimate the extent of the reduction, and relate it to recent observations of Raman linewidths and line shapes in ${\mathrm{Ga}}_x{\mathrm{In}}_{1-x}\mathrm{As}$ and ${\mathrm{Ga}}_x{\mathrm{Al}}_{1-x}\mathrm{As}$.