Extended x-ray-absorption fine-structure study of GaAsxP1-x semiconducting random solid solutions.

Abstract

The extended x-ray-absorption fine-structure (EXAFS) technique is employed to probe the local atomic structure of the III-V pseudobinary solid solutions GaAsxP1-x as a function of the composition. The first- and second-neighbor bond lengths as well as their variation with the composition are reported. The results imply that the local atomic structure is distorted. Both first-neighbor bond lengths and cation-cation bond lengths exhibit a bimodal structure, showing a tendency to retain the values of pure compounds. Anion-anion bond lengths are much closer to those predicted by Vegard's law; however they still show a significant deviation from it. On the basis of this result, the authors propose that the atomic-scale structure of these compounds can be described by a random distribution of five special coordination tetrahedra. The relation between local atomic structure and EXAFS as well as x-ray-diffraction results is discussed.