Investigation of GaAs based layers through the measurement of very weak x-ray reflections

Some GaAs reflections (002 and 006 for instance) are very weak due to the small difference in scattering factors between gallium and arsenic. The integral intensity of these reflections is very sensitive to the composition and hardly sensitive to the large crystal lattice defects like dislocations. The use of these 'very weak' reflections is the basis of a method that compares the integrated intensities for the investigated crystal with the reference, quasi-ideal crystal. Experimental data obtained with this method is compared with theoretical models of lattice point defects and local distortions. The main goal of this investigation was to find how the Be atoms are incorporated into the Be doped GaAs layers lattice, and to study the local microscopic structures around them. We can conclude that Be atoms substitute Ga in the lattice and there are also some lattice distortions in the first and second nearest neighbour shells