X-ray analysis of the short-range order in the ordered-alloy domains of epitaxial (ga,in)p layers by diffraction anomalous fine structure of superlattice reflections

Abstract

Ordered-alloy domains of epitaxially grown (Ga,In)P layers have been observed elsewhere using transmission electron microscopy and transmission electron diffraction. We used diffraction anomalous fine-structure (DAFS) experiments at superlattice reflections occurring in several (Formula presented) directions to explore the short-range order around Ga atoms in such ordered domains in epitaxial (Ga,In)P layers grown on (001) GaAs substrates. The requirements for a reliable measurement of the reflection intensity depending on the photon energy are described. A quantitative DAFS analysis resulting in short-range order parameters is explained in detail. The local structure around Ga in the whole (Ga,In)P layer (Formula presented) can be understood by a local structure model, while contrary to that the local structure around Ga atoms in the ordered regions (Formula presented) can be described by the values expected on the basis of the virtual-crystal model. © 1999 The American Physical Society.