DAFS STUDY OF STRAINED III-V EPITAXIAL SEMICONDUCTORS

The effect of built-in strain on III-V epitaxial semiconductors has be en investigated by Diffraction Anomalous Fine Structure (DAFS). We stu dy two different systems in a different strain regime: a Strained Laye r Superlattice of (GaP)(2)(InP)(3) grown on a GaAs(001) substrate, and a single epilayer of GaAs1-xPx. (x=0.225), also grown on a GaAs (001) substrate. In the first case the strain is accommodated by plastic de formation of the lattice, while in the second one it is partially rela xed by dislocations generation. The bond distances for the Ga-P and Ga -As pairs are obtained showing how they are affected by strain. The Ga -As pair shows to be ''softer'' than the Ga-P pair, i.e. more availabl e to accommodate strain by bond deformation, in good agreement with pr evious results obtained by different techniques. The DAFS provide a un ique tool of studing systems that are out of the reach of the other X- ray techniques.