Local atomic structure of semiconductor alloys using pair distribution functions. II.

A method of calculating the pair distribution function in semiconductor alloys has been extended to the differential and the partial pair distribution functions, and applied to pseudobinaries of the form $A_{1-x}{B}_{x}C$ with the zinc-blende structure. We have used a simple valence force model with bond-stretching and bond-bending forces. Results of calculations are presented for ${\mathrm{Ga}}_{0.5}{\mathrm{In}}_{0.5}\mathrm{As}.$ The differential pair distribution function provides a useful experimental way of determining the structural distortions in semiconductor alloys—specifically the mean nearest-neighbor and second-neighbor distances and widths can be obtained for chemically specific pairs of atoms.