EVIDENCE OF ORDERED PHASE OF GE-SI HETEROSTRUCTURES BY X-RAY-ABSORPTION SPECTROSCOPY AT GE L-3 EDGE

The structure of thin strained-layer (GenSin)(p) heterostructures on S i(001) is investigated by a multiple scattering approach to X-ray abso rption spectroscopy (XAS) at Ge L-3 edge. Our results confirm the abse nce of sharp interfaces for those Ge-Si multilayers grown without Sb a nd, in the case of very thin Ge2Si2 specimens, indicate the formation of a single phase, chemically ordered, Si-Ge alloy where the widely sp aced (111) planes are occupied alternatively by the same atom type. (C ) 1998 Elsevier Science B.V. All rights reserved.