Typical multilayers structures consisting of 3 periods with layers of GaAs and (GaAs)(1-x)(Si-2)(x) were grown using magnetron sputtering. Although these multilayers are not properly superlattices because of the reduced number of layers grown, the structures grown show multiple X-ray reflections, characteristic of superlattices. A group of samples where the GaAs intermediate nominal layer thickness was kept at 810 Angstrom, and the alloy layer thickness was varied from 260 to 645 Angstrom, was grown. In all samples the nominal concentration x=0.06 for alloys layers was maintained constant. Secondary ion mass spectroscopy (SIMS), Raman spectroscopy and high-resolution X-ray diffraction (HRXRD) have been used to characterize these structures. X-ray rocking curves show interference peaks that can be attributed to a good periodicity of the layers and the comparison between experimental and simulated results shows that x value is in reality 0.085. The a(\) and a(perpendicular to) lattice parameters were obtained and a 12% average relaxation is deduced for the alloy layers. From Raman spectroscopy measurements the atomic concentration obtained is approximately x=0.07 which is within the experimental variation of the concentration. SIMS measurements show good layer periodicity and a x=0.075 value for alloy layer that compares well with the results of the other techniques.