Determination of lattice parameter and of N lattice location in InxGa1-xNyAs1-y/GaAs and GaNyAs1-y/GaAs epilayers

We have used an experimental strategy that, combining nuclear reaction analysis and Rutherford backscattering spectrometry both in random and channeling geometry, allowed an accurate quantification of the total amount of N in InxGa1-xNyAs1-y/GaAs and GaNyAs1-y/GaAs epitaxial systems (0.038<x<0.044, 0.015<y<0.045), and a precise localization of nitrogen atoms into the lattice. All N atoms were found on substitutional positions. This information was then exploited to correlate the relaxed lattice parameter of the epilayers obtained by high-resolution x-ray diffraction to the N concentration, by taking into account the elasticity theory, allowing a verification of the validity of Vegard's rule in the whole range of investigated N concentrations for both alloys. The effect of N incorporation on the lattice parameter has been found to be the same both for ternary and quaternary alloys.