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 geometry has been used to study the strain accommodation in quantum well structures of InxGa1-xAs/GaAs (x < 0.25). The results show that a number of 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 correspond to the Ga-As and In-As bond distances in the binary compounds GaAs and InAs, respectively. This result is independent of the In molar fraction in the strained alloy layers.