Evidence of ordered phase of Ge-Si heterostructures by X-ray absorption spectroscopy at Ge L3 edge

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