GLANCING-ANGLE EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE STUDY OF STRAINED INGAAS/GAAS HETEROSTRUCTURES

The structural properties of strained InGaAs grown by molecular beam epitaxy on GaAs(100) substrates, have been studied by glancing-angle extended x-ray absorption fine structure (EXAFS), The very low incidence angle of the x-ray beam on the sample makes it possible to collect the signal coming from a thin quasi-surface layer allowing the study of a single strained sample built up by only 6 ML of InGaAs. The EXAFS results show that a slight deformation of the first shell Ga-As distance occurs and that the strain is accommodated also by bond-bending mechanism as deduced by the second and third coordination shells analysis. The lattice expands in the growth direction in agreement within the limits predicted by the elastic theory.