STRAIN EFFECTS ON THE MICROSCOPIC STRUCTURE OF AN INXGA1-XAS EPILAYER IN INXGA1-XAS/GAAS HETEROSTRUCTURES - A THEORETICAL-STUDY

Several strained structures of two ideal InxGa1-xAs compounds have been investigated by performing ab initio total-energy and atomic-force calculations in order to give a microscopic interpretation of extended x-ray-absorption fine-structure results on strained InxGa1-xAs/GaAs heterostructures. The achieved results show that the strain is accomodated by significant bond-angle distortions and small In-As bond contractions. A striking, stretched Ga-As distance (close to the In-As one) observed in the strained heterostructures should not be related therefore to the strain accomodation occurring in the InxGa1-xAs epilayer. Anisotropic strain effects are found, which lead to two different next-nearest-neighbor distances for atomic pairs on and out of the planes parallel to the InxGa1-xAs/GaAs interfaces.