MICROSCOPIC INVESTIGATION OF THE STRAIN DISTRIBUTION IN INGAAS GAAS QUANTUM-WELL STRUCTURES GROWN BY MOLECULAR-BEAM EPITAXY/

Extended X-ray absorption fine structure in the glancing angle geometr y has been used to study the strain accommodation in quantum well stru ctures of InxGa1-xAs/GaAs (x < 0.25). The results show that a number o f Ga-As bond lengths are stretched. Indeed, two Ga-As bonds distances coexist: 2.45 +/- 0.01 angstrom and 2.64 +/- 0.02 angstrom, which corr espond to the Ga-As and In-As bond distances in the binary compounds G aAs and InAs, respectively. This result is independent of the In molar fraction in the strained alloy layers.